Sundogboatbuilding

Vandemere 2012

2011-11-05T17:03:00.000-07:00

I knew it was a long shot getting the boat ready for the water by 28 October. I still have a couple of weeks worth of work to go. I am not even certain I will launch the boat before we close up shop in Rhode Island for the winter. Did you notice that I did not use the word finish. I hate to give Gary any fodder but someone once said that a boat is never finished................ until it sinks.

Well the good news is I definitely have a shot at having things ready for 2012.

Before I put the decking on I like to precoat the underside with two or three coats of epoxy. Since epoxy bonds best to either bare wood or green epoxy and bonds less well to fully cured epoxy, I usually leave uncoated the areas under the deck that will bear on framing.

This left an interesting pattern on the last piece of deck that closes up the bow. The large opening is there for the base of the mast to swing through. It make me think of a church and of course it lays just forward of the tabernacle.

This shows the framing under the fore deck. The arch was laminated from several layers of very thin wood. There is a lamp in there to help keep things warm so as to move the curing process along.

Here I have primer on the topsides, but still a long ways from being ready for the water.

Bowsprit

2011-11-02T16:36:00.000-07:00

Skorpa sports a removable bowsprit that allows her to fly a 250 square foot asymmetrical spinnaker. This more than doubles her working sail area of 238 sqft. I had a few questions about the bowsprit tube so I called Graham and he answered my questions and as he often does he also gave me a little trick to make the job go easier.

Getting the hole cut in the hull in the right place, with the right shape is a little tricky.

Here is Graham's helpful tip.

Locate the point 6 feet forward of the bow where the tip of the bowsprit should be.

Determine where on the forward bulkhead the base of the bowsprit sits.

Using your best judgement drill a hole through the hull in line with those two points.

Now run a string from the tip location through the hole to the base.

Move the hole until the string is straight and you have the center of the necessary opening in the hull.

I used the same trick to determine the forward and aft points of the opening.

I used a variety of methods to draw the outline of the opening, but knowing for certain the center point was critical to doing a reasonable job.

The opening came out pretty nicely. The carbon fiber bowsprit tube is laying on the deck.

I reinforced the area around the hull opening with 3/8 ply ' to give it some bearing' as Graham says. The I added some carbon and fiberglass tape. You can see the main mast trying out the tabernacle.

Carbon Fiber and Wood

2011-10-15T04:45:00.000-07:00

So why aren't carbon fiber and wood a good match?

Carbon fiber embedded in an epoxy matrix is light, stiff, strong in tension and compression, and expensive.

Wood is not nearly as strong, stiff, or expensive. Wood occurs naturally, is pleasant to work with, it can be beautiful, and wood is resistant to fatigue.

Lets say you designed a spar to resist a load of 600 pounds. You use enough carbon fiber to handle 500 pounds and enough wood to carry 500 pounds total strength 1000 pounds. Nice safety margin.

Now apply a force of 500 pounds to the spar. The carbon will flex very little say an inch. The wood will flex an inch readily resisting with say only 20 pounds.

Apply 550 pounds and you will snap the carbon. Now the entire load falls to the wood which will flex several inches before resisting with its 500 pounds. Then the wood will fail.

You would be better off designing and building the spar entirely of wood or carbon.

I did see an article in Woodenboat Magazine where they built a hollow wooden spar and lined the inside of the wood staves with carbon fiber and carbon rod.. Under load the wood fibers on the outer part of the stave will have to flex a greater distance than the carbon fiber laid on the inside of the stave. By adjusting this distance you could get the carbon and the wood to work more closely together.

But my spars have a carbon braid on the outside. The reason has to do with something called hoop strength.
If you design a hollow wooden spar with walls just thick enough to resist a certain load in tension and compression. The spar may fail prematurely because the walls buckle or splay apart under load. The spar needs more hoop strength.You could make the walls thicker but that would add weight. Or you could surround the hollow wood spar with a carbon braid to keep the wood squeezed into shape. The carbon fibers are running diagonally around the spar using their stiffness to keep the walls from bulging even a smidge. Since the carbon is not running straight up the spar the wood is free to flex and the two radically different materials work together to make a light and strong spar.

Carbon fiber and wood not a good match.

2011-10-05T18:33:00.000-07:00

Well not usually anyway.
Here I am coaxing a sleeve of braided carbon fiber onto the mizzen top mast.

If you pull on the braid it tightens like a Chinese finger trap.As you push the braid on it expands and shortens and then when you pull it out it lengthens and tightens.

Once the sleeve is in place I secured the ends with a hose clamp.

The main top mast is in the upper right waiting its turn to be swallowed by the braided black snake.

Spar Building

2011-09-28T19:29:00.000-07:00

The mast support came out very well so it is on to the mizzen mast. The top section of Skorpa'a masts are hollow wooden spars sheathed with carbon fiber braid. The idea is to make them as light as possible. At the top of the mast every ounce makes a difference, both when under sail and when raising and lowering the masts at the boat ramp.

Sitka spruce is light and strong also pricier than the construction grade Douglas Fir I have used for most of the solid wood on the boat.

The hollow mast is made up of 8 staves 10 feet long and tapering from 1 1/4 to 7/8 of an inch. I set up a jig to hold the pieces straight and in place. Graham likes to tack the first stave down to a series of blocks that have been leveled and that is what I decided to do.
Unless you have a lot of extra hands the sections of pvc pipe are needed to hold the staves until they lock together. I cut an octagonal plug for the tip and a piece of plastic tubing holds the base open. I am not using any glue here just practicing.

Seven staves birdsmouth side up are getting a very light coating of unthickened epoxy.

I made a notched spreader to help apply the thickened epoxy quickly and evenly, and as thinly as possible.

The first few staves go in pretty easily, but as you get past the half way point it is a little trickier.
With a little help form Sally who put down the camera to assist I got the last stave locked in.

Some people use hose clamps or wire ties but I think this idea I got from Charlie Jone on the Mess a Bout forum works great. I cut several old bicycle inner tubes into long strips. They go on quickly and put a gentle squeeze on the spar. The next day I unwrapped the tubes and cleaned up any squeeze out. I had two beautiful octagonal spars.

I drew a series of lines which guided me as I planed down the last two feet to give an additional taper. The I drew some more lines that allowed me to plane down the edges to make a 16 sided polygon. Whatever you call that.

You can see the lines on the mizzen.

By the time you get to 16 sides you are not that far from round so I planed the edges by I until the spar was close to round.

The mizzen is 16 sided.

Once I got the spars as round as I could with the plane I used sanding blocks made from cardboard or PVC tubing to round them completely.

A Thousand Miles A Thousand Things to do.

2011-09-23T17:17:00.000-07:00

Graham is hosting a Mess-a-bout in Vandemere, North Carolina on October 28, 2011. I would really like to be able to take Skorpa. I am not sure if I can have the boat finished. Time seems to be slipping away. I am putting in a lot of hours but progress though steady is still slow.

A few things like the forward deadlight, oar locks, compass, bow sprit, things that can easily added later I am leaving for now. I am still trying to do good quality work.

My mother told me to stop being so fuddy duddy and just finish the boat. She would like to see my work while she is still around.

The top sections of Skorpas masts are hollow wooden spars covered with carbon fiber braid.
Never having done a birdsmouth spar before I thought I would practice on a mast crutch that sits in the mizzen mast step during transport and holds the aft end of the two masts.

That is a view of the top of the mast crutch. It is two inches across. To make those cuts accurately I did a little work on my table saw.

The old metal insert is all bent and banged up and the opening is two large. I tried to straighten it. Then decided to make a new out of some plywood.

I put on a new blade and ran it up through the plywood insert making the cutout no larger than necessary.

When I bought my plywood I also bought some sitka spruce. It is light and strong.

The board on the left is the rough sawn wood I started with. After a lot of work I was down to some staves 9 feet long, 7/16 of an inch thick and tapering from 1 and 3/8 to 7/8 of an inch. All to make a tapered hollow wooden spar.

One of the staves is running through the saw. Two passes one on either side of the fence makes the birdsmouth cut.

Decking

2011-09-20T18:18:00.000-07:00

After Jim helped me get the large forward deck section glued down I worked my way steadily towards the stern.

I precoated the underside of each panel with two coats of epoxy.
I glued in 6mm ply under the butt joints in the deck. Under where the oar locks will go I set in some 5/8 solid wood to help distribute the loads.

At first the coaming structure felt fragile. Graham wanted to keep the weight down as much as possible so there is not a lot of extra in his scantlings. I was amazed and pleased though at how stiff and strong the coaming and side decks felt when everything was glued up.

Here is a view of the coaming before the side deck went on. The solid wood is only 5/8 by 5/8.

Graham told me I would want my oars to be at least 10 feet long. Since I added a lazarette the cockpit is only open for 8 feet or so. The solution is to build some tubes into the lazarette that will let the oars slide in and keep any water out.

I am wrapping some wetted out 6 oz glass onto a section of 3.5 inch aluminum tubing. I first covered the tubing lengthwise with one inch strips of plastic then wrapped that with plastic. When the epoxy sets up I slid the plastic out first then the fiberglass tube slipped off easily.

The tube is very light and was fun to make. I probably did not use enough glass, but what can you do.

The rear deck has its two coats of epoxy on the underside and is waiting to be glued in place.

All the decking except for a small piece in the bow is in.

Tabernacle

2011-09-16T17:57:00.000-07:00

What is a tabernacle doing on a boat? In lay terms a tabernacle is the dwelling place of the sacred.
On a ship a tabernacle is a structure on deck that holds the mast on a pivot that allows the mast to be lowered.
When you want to install the mizzen mast on an EC22 you pick the mast up and insert it through the mast partner and into the mast cup. The main mast is too heavy to install by hand so we are building a tabernacle. I have done some searching online to discover why the word tabernacle has come to be used to indicate this pivoting mast support, but I have not found anything convincing.

Here are the parts laid out.

The tabernacle goes just forward of the forward bulkhead. The mast must pivot through the deck so the forward compartment is always open. The floor slopes forward and there is a little drain near the bow. The forward compartment is a good place to store an anchor and line. I put a layer of 2 oz glass down to resist abrasion and water. The deck is reinforced on either side of the notch where the tabernacle fits.

Some temporary braces are holding the tabernacle while the epoxy sets up.

A little help from my Friend

2011-09-01T17:35:00.000-07:00

Our good friends from Virginia Jim and Jerryanne stopped by for a brief visit. While they were here we went for a lovely sail in some gusty winds, and Jim helped me put the foredeck on.

The deck is upside down on the bench. The underside has received two coats of low viscosity epoxy.

Jim is spreading thickened epoxy on the deck beams while I mix up another batch.

If you look closely you can see epoxy spread on the deck beams. I used a notched trowel to even out the coating. In the foreground you can see some of the reinforcement for the tabernacle.

Here comes the deck epoxy still sticky.

Trying for an accurate touchdown so we don't smear the epoxy everywhere.

There she is now let's strap her down.

Cam straps hold the deck down to the curve and steady it. Small adjustments can be made but it is not sliding all over the place.

Foredeck is in place. Temporary screws hold the edges down.

Thanks Jim.

Did I show you my knees?

2011-08-21T15:46:00.000-07:00

Knees on a boat are a framing part that carries a load around a bend. A knee connects two parts at a right angle or nearly a right angle. On Skorpa I am using knees to connect the deck beams to the side of the boat.

The curved part of the knee that faces the inside carries a compressive load. The upper part of the knee and the deck are in tension when a load is applied. The middle of the knee is not doing too much mostly just keeping the side in compression separate from the side in tension. The holes make the knee a little lighter without detracting much from their strength. They also make a handy place to tie things. And the holes make the knees look nice. I may have gone a bit overboard drilling holes.

Knees support the side of the cabin and the cockpit coaming.

The knees in the cockpit coaming have special holes to provide wiring to the compasses and for a tiller line to run the perimeter of the cockpit.

Deck Beams

2011-08-11T16:40:00.000-07:00

Here you can see the forward deck beams in place. The aft forward deck beam is in the background with the front of the cabin resting on it. The center forward deck beam is just forward of that and five small beams run for and aft on top of the main beams.

Here is another view.

The cabin side deck beam is visible. This piece was a little tricky to fit because it bends slightly as it comes around the side of the cabin.

Aft Forward Deck Beam

2011-07-21T18:08:00.000-07:00

Just the sound of this particular part of the boat sounds crucial to me. The Forward Deck or Fore Deck is the upper area of the boat in front of the cabin. The aft forward deck beam is the most rearward of the forward deck beams. It ties the the forward part of the cabin into the deck and supports many of the other deck beams.
At this point anyway I think of the aft forward deck beam installation as heralding the final phase of the building of SKORPA.

The AFDB is constructed of plywood and Doug Fir. The plans have a full size pattern for the plywood, but since I have extended my cabin forward 6 inches the AFDB had to move forward as well. Since SKORPA is not at all shaped like a box the beam had to be altered to fit its new location.

This step involves gluing solid stock 1/2 by 3/4 inch to the plywood to make a composite beam If you look carefully you can see that I used scraps of wood to form cantilevers so I could develop clamping pressure near the center of the table.

Next the beam is installed in the boat just at the front edge of the cabin which is suspended by a rope to the ceiling. Actually you can not see the rope holding up the cabin but you can see two other ropes. One is holding the AFDB up in place while the epoxy sets and the other is applying a little pressure inward on the gunwales.

The Aft Forward Deck Beam is in place and the forward part of the cabin settles nicely on her and becomes part of the boat.

The center forward deck beam uses plywood only for the knee part that transfers the load over to the hull. The span is constructed of five pieces of cedar laminated with epoxy. I mad a mistake with my measuring and built the first CFDB without enough camber. I considered soaking it and trying to put more bend into it or adding some spacers but in the end I decided to build a second one. Consequently I have lots of photos.

Each strip is coated with a low viscosity epoxy.

Then thickened epoxy is spread on one surface using a notched trowel.

Then the pieces are stacked one on top of the other. As you can imagine this can get messy. Thickened epoxy has some of the properties of grease.

My form consists of a series of block clamped in place on the plastic covered table. The position of these blocks determines the camber of the beam.

Clamps are added to squeeze the layers together and to keep them all pressed flat against the table.

There is a delicate balance. You should have enough epoxy evenly spread on the parts. The pieces need to be held flat to the proper shape and squeezed together hard enough to get some squeeze out but not so hard that most of the epoxy is squeezed out and you have a starved joint.

There is normally some spring back when the beam is removed from the form. The narrower the strips and the more flexible the wood the less spring back occurs My beam straightened out less than 1/8 inch..

Cuddy

2011-04-19T15:04:00.000-07:00

A Cuddy is a small cabin usually without standing head room. There is about one inch of room above my head when I am sitting in the cabin. That is sitting on the bunk with out any cushions. Graham designed the cabin to be as low as possible and still provide sitting head room. A lower cabin means less weight, less wind-age, and less interference with visibility from the cockpit.

To provide maximum headroom the cabin is built without beams. The roof is self supporting. It is constructed of three layers of 4mm plywood laminated in place over a mold.

The cabin is about four and a half feet wide and about six feet long. This makes for a good size project. The cabin is one of the steps in the boat that I thought were a little intimidating. Lots of curves, lots of unknowns.

Well here we go. First the temporary forms are set up in the cabin.

Then one layer at a time 4mm plywood is bent to the forms.

The next two photos show the second layer going on. That is all Graham put on his boat Southern Skimmer. He told me he has felt the roof start to oil can when he was walking on it so he specified three layers in the plans.

The clamps are off and the second layer is complete.

Here I am using a notched spreader to apply thickened epoxy to the roof in preparation for the third layer.

Then on goes the final layer. I am using screws, battens, staples and clamps to try to apply even pressure over the entire area. Fortunately it is cool in the boat shop around 50 degrees Fahrenheit so I have some time before the epoxy starts to set up. This is similar to the way the hull was laminated.

This is the third layer clamped in place.

Next is one of the tricky parts. The roof which was initially made over size has to be cut back so that a stick or a piece of plywood laying against the two temporary forms will just make contact with the roof. I used a notched stick to trace a line in the top of the cabin, but there is a lot of fudge work involved especially coming around the corners.

Next the sides of the cabin are bent into place. The grain of the plywood must be aligned with the area of greatest curvature.

There will be two layers on the sides and the first one is on.

After I completed the sides I removed the upper mold and the temporary roof beams. I left the lower mold in place to give a little stability to a relatively fragile assembly. At this point everything is held together by a thin layer of glue where the cabin sides meet the edge of the roof. Gluing onto the edge of a piece of plywood makes for a weak joint, so the cabin was very carefully lifted off the boat and flipped upside down so the joint could be reinforced.

Here the cabin is inverted and I have started to lay a large fillet into the seam between cabin top and sides.

In order to lay a nice smooth fillet you might think you would want your thickened epoxy mixture to be smooth and creamy, but it ain't so. And the bigger the fillet the thicker and dryer the mixture should be.

That is some good stuff. Dab it on and hit it with a spreader and you have an even and surprisingly smooth fillet.

After the fillet was firmed up a little I added two layers of 6oz tape. I cut strips four inches wide from some left over cloth. Once the joint was reinforced I could round over the joint from the outside. There was a couple of inches of material sticking up in some places where the side pieces overlapped the roof. I cut the bulk of this off with the saber saw. I thought I would try out the grinder with an abrasive disc and it proved quite effective. Not a fine woodworking tool, but it did a nice job here.

The grinder can leave dip and bumps in the cabin. The long board is slow but it can help make the curves fair.

Once the joint was as round and fair as I could stand to make it everything got a coat of epoxy and the joint got two layers of the home made 6 oz tape. Now the cabin is fairly strong and I can move it around without worrying that I might stress the joint.

I decide to paint the interior of the cabin white. I tried using System Three water reducible polyurethane paint.

The lack of obnoxious fumes made the paint very pleasant to use. However even though the boat shop was a cool fifty something degrees and I used a sprayer to raise the humidity I found the paint dried very quickly and so was difficult to apply smoothly with a roller.It came out decent if you do not look too closely.

I decided to add a hatch for added ventilation and hopefully the ability to reef the main from a secure location.

I did not want the hatch any bigger than absolutely necessary. I made an opening out of scrap lumber clamped together and made adjustments until I found a size I could just comfortably squeeze through. 15 inches wide and 12 inches fore and aft. I did not really have a plan. I just figured I needed a raised level surface with a lip to keep out water. The cabin roof is curved so I spent a lot of time shaping and fitting the pieces.

I found several feet of some very thin and even 1/16 by 1 1/2 scrap. I soaked this a couple of days in water and then was able to bend it to a form and let it dry. I laminated three layers of this on the inside to make a lip or coaming around the hatch opening. I don't know if this is the right way to make a hatch but it certainly was a long way.

Now all I have to do is make the hatch cover.

I wanted to keep the hatch as light as possible so I used 4mm ply with a layer of glass on the underside.

Nest is returning the cabin to the boat and reattaching it to the cabin bulkhead. Quite a while has past and some glassing and filleting has occurred so not surprising a little filleting needed to be removed and some persuasion applyed before the cabin settled onto the cabin bulkhead.

Forward Compartment

2011-04-13T18:09:00.000-07:00

There is a sealed flotation compartment in the bow. At the bottome of this compartment a stainless bolt comes through the hull and is bonded to an aluminum strip that will in turn connect to the base of the main mast.

Here you can see that the compartment and the underside of the deck are well sealed with epoxy.

This floor forms the base of the main mast tabernacle.

Spring is here.

2011-04-10T18:02:00.000-07:00

My winter was spent in Virginia. Doing things that needed to be done that are alas not as much fun as boat building.

But Spring has arrived and Sally and I are back in Rhode Island where Skorpa has been waiting patiently.

Building the cabin is the big job that is next on the agenda. The EC 22 cabin has lots of curves and looks quite stream lined. It is made by laminating layers of 4mm ply over a set of molds.

Cutting and installing the cabin bulkhead is the first step.

The bulkhead is inclined forward 6 degrees. That is about 2.5 inches at the end of the two foot level.

This is a good size bulkhead so it required a variety of screws clamps and props to hold it in place while the epoxy set up.

Once the bulkhead was in place I laminated a beam in place across the top.

I wanted the beam to be 3/4 wide and one inch deep. In one piece it is way to stiff to take the bend across the top of the cabin. But in a piece 3/4 wide by 5/16 deep the curve was easily made. After the first strip had set I laminated in the other two.

Rudder

2010-09-27T18:40:00.000-07:00

Skorpa's rudder hangs down into the water about 2 1/2 feet. The rudder needs to be able to swing up when the boat is in shallow water.

So I need to build a kick up rudder. The blade will have a foil shape much like the centerboard.

The rudder blade is in fact constructed in a similar manner to the big board.

Vertical grain cherry and walnut strips were glued up to form a blank and then worked into a foil shape.
My favorite shaping tools are in the photo. The tools seem to work in some situations and then sometimes not.Then I either sharpen the tool or try a different tool until something works.

The shaped blade has been sealed with unthickened epoxy and is waiting to be covered with glass cloth.

The extra glass around the edges will be trimmed when the epoxy has firmed up but before it gets rock hard.

In this photo you can see where I have made epoxy bushing around areas where there are holes into the blade.

You can see the pivot pin protruding from one bushing. The upper bushing is for the stopper knot on the uphaul line.

These are the rudder cheeks. They house the blade and hold the hardware( pintles and gungeons ) that attach the rudder to the boat.

The third and last time.

2010-09-27T18:03:00.000-07:00

The bottom is glassed and painted. The keel strip is screwed and bolted in place. It is time to roll the boat back right side up.

This getting to be a familiar routine. First step is to roll the boat into the driveway.

Then invite some friends, neighbors, and relatives over.

There is a lot of weight on the relatively unsupported inwale.

I have temporary thwarts in place but the inwales will be much better supported when the deck is in place.

Here six of us are picking the boat up and moving it back onto the building frame.

Sanding and Painting the Hull

2010-09-17T18:05:00.000-07:00

I applied the epoxy carefully but I still had some sanding to do after the epoxy had set good and hard.

I made an adapter so I could fasten a full sheet of sandpaper to my sander. The big sheet of sandpaper floated over the hull and did a good job of smoothing the hull without making dips or gouges.

Once the hull was smooth and fair I applied two coats of epoxy primer. I could not get the primer to apply smoothly so my paint job was disappointedly rough. It looked like one of my better stucco jobs.
The paint I am using is a Devoe product intended for industrial application on things like bridges and water tanks. The paint is formulated so it can be sprayed. It took me awhile to learn that adding a little of a special reducer T-17 slows the drying down and makes applying with a roller much easier.

I did the painting outside under a tarp for maximum ventilation.

I did not get the near perfect finish I had been hoping for but after a bit of scrambling and a lot of sanding I was able to salvage a decent looking finish coat.

White is to minimize heat absorption to and maximum visibility.

All white is just too plain so I am adding some contrasting color. You can see the masking in place for a dash of red.

Before the hull can be turned back over I need to attach a keel strip that is protected by a metal band.

I bought 18 feet of stainless steel 3/16 of an inch thick by 3/4 of an inch wide. The steel needed to be drilled and countersunk for screws every 6 inches.

Sally's brother David kindly let me use his heirloom drill press.

The 316 stainless is not easy to drill. Lots of cutting oil and a bit of smoke.

The screws fasten the steel band to the keel and the keel is epoxied to the hull.

The steel band is intended to prevent wear to the hull when beaching, running aground or loading on the trailer. I thought it could also serve as part of a system to ground the aluminum masts in case of a lightning strike.

So just below the main mast and just below the mizzen mast I have placed bolts that go through the hull.

Where ever a fastner penetrates the hull I drill an oversize hole and fill that with epoxy. After the epoxy hardens I drill the proper size hole for the fastner. This helps prevent any water that penetrates around the fastner from getting into the wood.

A straw and syringe allow me to fill the hole from the bottom up so there are no air pockets left in the hole.

While the boat was upside down I decided to paint a boot top. I painted a 3 inch stripe of gray centered more or less on the waterline and topped that with a 1 inch stripe of red.

Originally I was going to use bronze as a keel strip and bronze half oval at the bow. Bronze is a much better conducter of electricity than is stainless steel. I had a difficult time finding a source for the bronze. Bronze is also highly reactive with aluminum. So after a lot of hunting around for bronze I went back to the more commonly available stainless steel.

Getting a clean paint line when you are taping off one color from another is not easy.

Those little bits of red are called flags. That is where some of the red paint seeped under the tape.

I learned a neat trick to prevent flags from occurring. It requires an extra step.

After you apply the tape. Paint a little of the base color, in this case white along the edge of the tape. Let that dry. If the paint finds a way under the tape it will leave a little white flag and seal the path so no red can follow.

Much cleaner edge using the two step process.

I have organized a boat rolling party for Sunday.

So while the paint is drying I am working on the rudder.

Glass Bottom Boat

2010-08-09T07:14:00.000-07:00

Skorpa is primarily made of marine grade plywood. Fiberglass is used to reinforce areas of high stress and to protect areas from abrasion. The fiberglass I use is a woven cloth like material. Fiberglass can be made from synthetic materials, but what I use is related to the fiberglass that is used to insulate houses. Glass fibers are spun into thread and woven into cloth.

Here the hull is draped with 6 ounce cloth. I carefully laid the cloth out and worked to smooth out all the wrinkles. When I had the cloth fairly smooth I tacked it in place.

The epoxy is poured on and spread with a squeegee. As the epoxy soaks into the cloth the fibers become transparent.You have to put enough epoxy on to saturate the cloth but not so much you float the cloth off the hull or start runs of epoxy. You have to use enough pressure to move the epoxy but not so much you move the cloth. Is there any wonder I have trouble sleeping the night before?

The roller works best on vertical surfaces. I can get a thinner layer of epoxy. Building the epoxy up in several coats allows me to get the desired thickness without runs.

After I have the epoxy spread out evenly with the roller I go over the surface lightly with a foam brush to remove any air bubbles or roller marks. This leaves a pretty smooth surface so there should be less sanding to do.

Finding the centerboard trunk

2010-08-09T07:09:00.000-07:00

Before I glued in the centerboard trunk I drilled a hole through the hull in the area covered by the inside of the trunk. This allowed me to know the location of the trunk now that the hull is inverted.

I made a jig to hold the router roughly perpendicular to the trunk and started the cut in the locating hole.

Similar to the way I cut out the seat tops. The router with a bearing tip did a good job of following the inside of the trunk.

After the slot was cut I could not resist temporarily installing the centerboard.

Here the board is retracted. The pin is installed. Seems like a nice fit. No extra wiggle room.

After I got the board back out of there I used the round over bit to (duh) round over the lip.

I used fairing compound to fill any small hole or imperfections at joints in the hull. Then a light sanding and the entire hull was sealed with unthickened epoxy.

I used a combination of squeegee and roller to spread the epoxy.

A foam brush is used to remove any bubbles or marks left by the roller.

Now the hull is ready for glass.

Move em out and roll em over

2010-08-09T06:39:00.000-07:00

Sally and I rolled the boat out and a few neighbors came over to flip Skorpa back upside down so I can glass and paint the bottom. I cut the laminated stem flush and thought this made an interesting photo. You can see the inwales where they join the stem and the plywood hull panels meeting at the bow.

This is my second time flipping the boat so things were fairly relaxed.

Four of us were able to flip the boat with no problem.

When the four of us picked the inverted boat up to set it back on the frame we had the full weight which I think must be around 400 pounds.

A visit from the Designer

2010-07-14T18:20:00.000-07:00

Graham Byrnes stopped by on the way between a boat show at Mystic and some boat building classes in Maine. He and Beth stayed a couple of nights with us. One of the reasons Graham stopped by was he wanted to see how I am coming along on my boat. No one else has built an EC 22. Graham has made several changes from the first EC 22, Southern Skimmer, so he has been following my build with interest.

Graham said the boat was looking great.

He did notice a few places where stringers which stiffen the hull end abruptly at a bulkhead.

Graham referred to this as a pin joint.

Though the photos look much the same here the stringer continues right through the bulkhead.

This forms what is called a fixed joint. Much stronger. It is not always practical to continue the stringer through the bulkhead. You can taper the stringer and bring it to an end a few inches beyond the bulkhead.

Graham suggested that I place a fillet and some fiberglass around the area where the stringers end at a bulkhead. He thought that would distribute the stress and prevent any problems from developing.

If you look closely you can see a fillet and some fiberglass around the area of the stringer to bulkhead joint.

I was a little bummed when he told me about my pin joints but it did not take that long to patch them.

They look much better to me now.

Seat tops and bunks

2010-07-14T17:37:00.000-07:00

The large piece of plywood I am working on forms the forward cockpit seats, centerboard trunk top, bridge deck and mizzen thwart.

I needed to cut out the openings for the foot wells and I thought I would try a different way of making the cuts.

I am using a special bit in the router. The router bit has a small bearing on the tip. Once the bearing comes up against something solid it will not let the router cut any deeper.

This makes lots of dust and is kind of scary because you have to trust that the router isn't tearing into the centerboard trunk you spent three weeks building and installing.

All in all very successful. The center board trunk emerged unscathed.

I survived as well. A router is an amazing and scary piece of equipment.

Marissa stops by for a visit

2010-07-09T18:51:00.000-07:00

Graham Byrnes entered Woodenboats design contest for a fuel efficient 25 hp powerboat. He won with his design for Marissa. Graham took Marissa to this years Woodenboat Show at Mystic Connecticut. After the boat show Graham and his daughter Beth had a few days before they had to be in Brooklyn, Maine to teach two weeks of boat building courses.

Graham and his crew had burned the midnight oil to get Marissa ready in time for the boat show. There were a few details that had to be attended to before Marissa could be launched.

I drove Graham into Galilee and he bought some bolts and fuel line at Rhode Island Engine Company.

Then he and Beth went to work.

Soon we were off to the boat ramp.

Cruising past the fishing fleet we headed for the breachway and the open water of the Harbor of Refuge.

Graham could hardly wait to open the throttle and see how Marissa will run. This is her maiden voyage.

Pretty smooth wake as we skim across the water.

Sally is sharing some local knowledge with Graham while Beth enjoys the ride.

After touring around for awhile we anchored Marissa on some sand flats and dug for quahaugs. We all enjoyed gathering the hard shell clams for our chowder. It was a late supper and a good day on the water.

Making an offering

2010-07-06T17:45:00.000-07:00

All that framework is there to hold the 6mm plywood that forms the bunk tops and seat tops.

As you can see in the photo there is a lot of curvature in the hull up front. All that curvature makes fitting the bunks tops a bit of a challenge.

Making the tops out of as few pieces as possible keeps them light and strong. Meeting the hull on two or more sides is very tricky because if you have to do a little trimming you can end up making the panel too small.

To get around this problem I made a template out of a couple of pieces of scrap ply. That way I could individually fit each side until it was just right. Than I secured the two halves together.

Here I am laying out the pattern on my good plywood.

The result was a very nice fit.

I tried using cardboard to make a pattern and it works alright. The cardboard is a little compressible though so you do not get as accurate a fit as with the more rigid plywood.

If the bunk or the seat top meets the the boat on only one side or on two adjacent sides you have it a little easier. You can get a rough fit and than use a block of wood and the side of the boat to scribe a line on the plywood. Plane down to the line and you should have a nice fit.

Once you have the piece shaped to your satisfaction you can "offer it up" to the boat.

My boat has never accepted my offering the first time around. Sometimes after many attempts I just say that will have to do.

Joinery

2010-06-24T18:23:00.000-07:00

The interior of an EC22 has a fair number of small parts that form a framework which functions to stiffen the hull and support the horizontal surfaces like bunks, seats and decks.

Most of these framing members are pretty light. Like 3/4 inch by 1 inch. Or under the bunks 5/8 by 1.

The framework is so light that you have to take care that the joints are as strong as possible without unduly weakening the framework.

This is some of the framework that supports the bunks. I give each piece two coats of epoxy before I glue it in place. Epoxy loves to drip and run. Coating the pieces after they were installed could get ugly.

This is a butt joint. Simple to make, doesn't weaken either piece of wood, strong in compression, but weak in tension and in shear.

This is a mortise. Much stronger in shear, but you have to take a chunk out of one piece. It is not real easy to make the mortise.

I am not sure what this joint is called. I will call it a diagonal. I had not been aware of this method of joining wood until working on Skorpa.
At first I did not like the looks of it because it seems like the pieces could just slip apart under pressure.
Epoxy is pretty strong though and if it has some plywood on top to keep the joint from spreading than the diagonal is quite strong. Good in compression, tension and shear. Minimal weakening of the adjoining pieces and not too difficult to make.

I mark out the lines usually for 45 degrees. Saw cuts outline the sides and help control the depth.
A sharp chisel takes out the wood.

There are several variations on the basic diagonal.

These pieces will support the bridge deck on either side of the centerboard trunk.

Here we are under the port bunk. 4mm (1/8 inch) plywood webbing ties the hull stringer to the bunk framework. I use Mikes router to round off the underside of the framework.

View of the starboard bunk from above.

It is taking a long time for me to finish this boat. Yes I am having to learn as I go. I am trying to work carefully and do quality work. I also have a lot of other responsibilities to attend to.

Cockpit interior

2010-06-01T19:05:00.000-07:00

What a strange word.

Cock Pit.

A depression in which roosters fight.

The location of many battles.

An open area near the stern of a vessel below the level of the deck from where the vessel may be steered.

I covered the floor of the cockpit with a layer of 2 ounce fiberglass cloth. This cloth is so light it does not add much strength. I have read that it adds significant resistance to abrasion without much additional weight, so I thought I would give it a try.

When the epoxy saturates the cloth it turns clear as glass.

Here the cloth has been wetted out and stringers have been glued in place to stiffen the hull.

This is a view through bulkhead # 4. You can see a piece of scrap wood holding the stringer in place while the epoxy sets up.

Looking forward from the Lazarette.

The Mizzen mast sits right in the middle of the cockpit.

The Mizzen mast step must hold the base of the mizzen mast securely. This rig has no stays. The mast step and the mizzen mast thwart have to bear all the loads placed on the mast.

The mast step is laying beside its intended location. There is so much force on this part Graham thought it best to use mechanical fastners (screws) in addition to epoxy to make sure the mast step holds.
Wherever fastners penetrate the wood moisture can find a way into the wood.
I drilled oversize holes and filled them with epoxy. Then I redrilled the proper size hole for the fastner.

Undoubtedly overkill for a boat that will be dry sailed, but what can you do?

Centerboard Trunk

2010-05-17T18:24:00.000-07:00

The centerboard trunk sits over a long narrow slot in the hull of the boat. The trunk must be water tight and strong enough to support the board. A lot of force can be applied to the extended board.

Someday I might get the board stuck in some mud. The wind and tide might try to twist the boat while the sticky mud tries to hold on.

So two layers of cloth on the inside and one on the outside of the trunk.

Trimming the excess cloth.

The two by two looking piece of wood with the clamps is the king post.
The width of the king post determines the width of the trunk. Too wide and the board might rattle.
Too narrow and the board might jam.

I did not glue the king posts until the very end so I could adjust their width.

The carbon gets everywhere.

The center board pivots on a bronze pin.I drilled out an oversize hole filled it with epoxy and then redrilled so the pin will rest in a epoxy bushing. The cap covers the hole so no water gets in.

All the screws get their own epoxy bushing.

The trunk gets a trial fit. The trunk is supported by two bulkheads. Here you can see the trunk protruding through bulkhead # 3 into the cabin.

Centerboard

2010-03-29T18:47:00.000-07:00

Graham has redesigned the centerboard for EC22. He wanted to remove an annoying touch of lee helm. which became worse when the board was partially raised as when sailing close hauled in shallow water.

The new centerboard has a lead tip sized to make the board sink and stay on the bottom but kick up readily if an obstruction is encountered.

First task is to laminate a dozen or so boards to make a 61 inch by 16 inch blank. Laminating from a lot of small sticks is time consuming but allows you to select for good straight wood and control things like grain orientation. Hopefully this results in a centerboard that has little inclination to twist, bow, warp, crack or mess up.

There needs to be enough lead on the board to make it sink and stay down even when the boat is at speed.

Graham suggested about 15 pounds of lead. Someone else used about 18 pounds for a similar board.

I decided to try to calculate the weight of lead needed and the amount of the board that should be lead.

That is should the bottom 2 inches of the board be lead or bottom 4 inches or 6 inches?

I could figure this out empirically by taking the completed board out into the water and piling weights on it until it sank. Then add a few pounds for good measure.

Another way involves calculating the volume of water displaced by the board and using the density of the board and the density of water to arrive at the amount of lead needed.

I carefully measured and weighed my centerboard blank to determine a density or 0.017 lbs/cubic inch.

The density of water is 0.036lbs/cubic inch

The density of lead is 0.409lbs/cubic inch

The density of my Douglas Fir centerboard is about half of the density of water.

After the blank was glued up and smoothed I cut it to shape in two dimensions. Then I marked the edges in preparation for shaping the board in the third dimension.

Did I mention that some centerboards are flat, however a board with a air foil like shape is more efficient.

I used a plane and a draw knife to bring the board to shape.

I was able to transfer the profile of the board from the plans to some scrap plywood. These helped guide my progress.

Here the board is nearing its final shape.

The weight of the blank was 22 pounds.

The weight of the shaped board was 15 pounds.

15 pounds divided by the density of the board 0.017 lbs/cubic inch = 882 cubic inches.

Not all of the board is submerged when it is installed in the boat and lowered only about 700 cubic inches.
700 cubic inches of water weigh 700 x the density of water 0.036 lbs/cubic inch = 25.2 pounds.
700 cubic inches of board weigh 700 x density of board 0.017 lbs/cubic inch = 11.9 pounds

25.2 pounds- 11.9 pounds = 13.3 pounds of lead would just make the board neutral.

I want to have the board sink with authority so I will add an extra 3.7 pounds for a total of 17 pounds of lead.

How much of the board will be taken up by 17 pounds of lead?

Archimedes anyone!

I put some marks on the board.

Up until this point you may have thought I was pretty clever.

Several things could have been done to make the removal of the board from the concrete easier. I do not know where I was but alas none of them were done.
I hung the board from the ceiling and used progressively larger hammers to pull the board from the stone. Fortunately before doing any serious damage I moved to plan B.

Plan B was to use a concrete saw to cut a shallow kerf around the block and than strike the block in order to split it open. I heard a change in the sound of the hammer and slowly I was able to work the board free, though I was not able to find a crack in the block. This is when I said

Eureka !

Next we need to cast some lead.

I wanted to insure that the concrete was absolutely dry before pouring molten lead. Instant vaporization of the moisture can lead to a small explosion spraying molten lead everywhere.

After a brief consultation with Sally I decided that the 60 pound block of concrete was not going into the oven.

Fortunately I remembered seeing an electric element intended for lighting charcoal on the shelves in the cellar.

After the element had been on for several minutes I noticed steam rising from the form. Looking inside I could see drops of moisture in the mold. They were being drawn out of the apparently dry concrete.

I added lead from an old centerboard and wheel weights to an old iron pot heating over a backpacking stove.

After about an hour the lead was molten. I then skimmed the dross from the surface of the molten lead.

I tried to stay upwind.

Finally the big moment. Pretty incredible watching the molten lead flow bright and silver thin as water.

I had wanted to make the pour in one shot but I ended up a little short and had to melt some more lead.

I think I should have kept the surface of the lead in the form molten by working it with a propane torch, but I did not think of this until later.

The result is a bit of a cold joint, but I do not think it really matters for my purposes.

I thought the lead looked very good even the surface seemed free of impurities.

I let the pour sit overnight.

I removed the box and after a few wacks with a hammer.

I think it looks beautiful. Not too shabby for my first casting.

The target weight was 17 pounds.

I will lose a little when I dress the casting, but I am sure it will end up over 16 pounds.

More later.

Lead is fairly soft. I used a rasp and a block plane to shape it.

I considered placing some pins to help align and attach the tip to the board. Graham assured me that a simple butt joint reinforced with fibergass would be strong enough. A pin located near the center of the axis would provide little additional strength. Intuitively it just seemed a little dicey. The lead is sooo heavy.

I drilled a hole in the lead tip and jammed an epoxy soaked rope into it. The rope lays in a groove that runs down the leading edge of the board. I placed the rope under about forty pounds of tension until the epoxy was set.

.

I draped two layer of 6 oz cloth around the leading edge and about two thirds of the way down the board.

Then I flipped the board so the trailing edge was up. I draped three layers of 2 oz cloth around the trailing edge and to the middle of the board. The lighter cloth was able to make the tight turn at the trailing edge

Here I am using a roller to apply epoxy to the 2 oz cloth.

The fiberglass cloth has been applied and wet out. now I am filling the weave with epoxy to which a little carbon has been added. The carbon epoxy mixture results in a low friction and abrasion resistant finish.
So hopefully the board will rotate up into and down out of its case smoothly.

Speaking of which the case is barely larger than the board in length, depth, or width.

Here the nearly completed board is laying on one half of the case.

I decided to test empirically the buoyancy of the completed board.

The board when completely submerged has a slightly less than one pound tendency to sink.

About four or five pounds of force is required to hold the board at the design waterline.

The black and white pattern on the board is caused by my shadow

The lead tip was sized about right

I am very pleased. The next test will come when the board is installed in the boat.

Heading North to escape the snow.

2010-03-29T18:31:00.000-07:00

I have been looking forward to heading back to Rhode Island so I could get back to work on SKORPA.

Putting up firewood, felling saw logs, sawing lumber, erecting a fence all tasks that needed to be done. None of them made easier by the beautiful white stuff. A couple of weeks later than I had hoped we left Virginia and headed for my long silent boat shop.

Everything was just as I had left it. Not a thing had been done.All the work I had done last summer looked pretty solid. Nothing had sprung apart.

First order of business is to glue in the mid transom beam. It was already fitted just needed some creative clamping arrangement to hold it in place.

I need to put pressure on the beam running down the center inside of the transom, way too deep for any clamp I own to reach.

With some scrap lumber and my ordinary C clamps I have an arrangement that can put just the right amount of pressure just where I want it.

Here as the clamps are being removed you can see that the mid transom beam is laminated from two pieces and wraps nicely around the king post or whatever that big board going up the center of the transom is called.

High on the list of things to do is the centerboard and centerboard case.

Interior work

2009-10-13T04:32:00.000-07:00

Sally and I are preparing to head home to Virginia. Skorpa is not ready to come with us yet. Here are a few photos to bring things up to date.

I placed some glass fiber to reinforce the forward section.

This is a view looking down into the forward section. Bulkhead number one has been filleted and taped.

Framing in the seats.

Here are a few shots just to show where we are. She is beginning to look like a boat!

Bulkheads

2009-09-21T15:38:00.000-07:00

After running fillets and fiberglass tape on both chines it is time to install some bulkheads.

This is the aft bulkhead along with a nice assortment of my clamps.

Then I did bulkhead number 3 the lower cabin bulkhead.

In the lower cabin bulkhead you can see a slot on the left side. This slot will be enlarged later to accommodate the the center board trunk. The trickiest part of installing a bulkhead is getting the right shape to fit. The aft bulkheads have fairly straight lines so it is possible to take several measurements and come up with a close approximation of the required shape.

The forward bulkhead is a bit more complex. I used a different strategy.

I used a plumb bob to establish a line where the bulkhead will meet the hull.

Sally is checking out the pattern I have made. I installed a scrap piece of plywood in the location for bulkhead number 1. Then I stapled little scraps of plywood like fingers touching all the important points around the perimeter and some inbetween.

OK now what?

How did that cat cat up there without altering the precise position of any of my indicator strips?

I made a mark at the tip of each indicator strip, connected with some fair lines and cut out with a jig saw.

What do you do with a very large skiff?

2009-09-16T18:05:00.000-07:00

Here are some photos taken just after the jig was removed.

I fitted some temporary thwarts to hold things together until some of the internal structure is installed

That is the stem sitting up there in the bow. I had some concern that something would spring loose when the jig was removed, but all the plywood acted like it had no intention of going anywhere.

What do you do with a very large skiff?

Why you fillet.

Pronounced fill it.

Thickened epoxy is placed in the chine and then shaped to a concave surface.

After the fillet sets up just a little, a layer of fiberglass tape is laid down. Then the glass cloth is saturated with unthickened epoxy.

Lets get her setting on her DWL

2009-09-15T18:07:00.000-07:00

DWL is the design water line.

If a boat is sitting on a very still lake, the line around the boat that the surface of the water creates is right on the DWL. That is if the boat is loaded properly and everything went according to plan.

I wanted to do two things before I removed the building forms.

First is to level the boat fore and aft as well as side to side. It is easiest to do this before the jig is removed because the base of the jig lies in a straight line parallel to the DWL.

Sally is adjusting one of the straps that has the hull suspended so it can be leveled and a cradle fitted under.

Second is to build a cradle that will support the boat while I finish the interior.

This is the forward cradle. I wanted something to hug the hull and prevent the forward sections from spreading when the jig was removed.

This is a support for the hull about two feet forward of the transom.

My third support structure is a little less elaborate. Go figure.

Roll Roll Roll your Boat

2009-08-09T17:03:00.000-07:00

My boat moves out to see the light of day.

The boat and jig together are pretty heavy.

I can not even lift one corner of the boat.

It feels like it is fastened to the ground.

I use pipes for rollers. Sally and Judy help me roll the boat out into the driveway.

Hoping for a soft landing.

Many thanks to my neighbors the Baldwins and the Ciolfis for their able assistance.

Back to bed right side up.

Goodnight

Zenos Paradox resolved

2009-08-09T16:46:00.000-07:00

The stem of my boat was not moving and yet I have been having trouble reaching it.

Finally I remembered Marks solution to the paradox.

I got as close as I could to the stem, then I bridged the gap with some epoxy thickened with wood flour.

Voila!

The hull planking is complete at last.

Next the boat needs to be rolled over so that the temporary forms can be removed and the interior finished.

Zenos paradox

2009-07-26T18:02:00.001-07:00

Or why it is taking so long for me to finish the hull of the boat.

Zeno was a 5th century B.C. philosopher.
Achilles was trying to catch a tortoise. No matter how fast Achilles would run, by the time he reached where the tortoise was the tortoise had moved a little further. Thus Achilles could never catch the tortoise.

To paraphrase the paradox.

On the first day you complete one half of the distance to your goal.

On the second day and each subsequent day you complete one half of the remaining distance.

You will never be able to reach your goal because there will always remain at least a small distance between you and your goal.

The first plywood hull panels went on fairly quickly. They were pretty big and pretty flat. Before long I was working towards the bow.

As the hull developed more and more curve the panels had to be made shorter and shorter so they could be bent to the shape. Because the panels are curving the straight edges of the plywood could no longer simply be butted together.

To fit nicely each edge had to be gently curved.

The closer I got to the bow.

The more difficult the fit and the slower my progress.

The piece in the foreground is dark because I have soaked it to make it take the shape more easily.

There is more than one way to scarf a cut

2009-07-26T06:16:00.000-07:00

The plywood pieces that make up the hull need to be fastened together.

You can butt the ends together and reinforce with epoxy fiberglass.

Or there is the hard way.

When you cut through plywood at an angle the layers of wood form an interesting pattern.

In a previous post What Knot I described cutting a scarf joint in the 1x4 by 24 foot board that was to become the keelson.

Here I am cutting a scarf joint in the 1/4 inch plywood that is to become the sides of the hull.

I have been too chicken to try to get the circular saw to cut the slope down to a feather edge so I finish the job with a plane.

Here are some of the panels forming the side of the hull.

Hull

2009-07-01T18:23:00.000-07:00

The bottom hull panels of an EC 22 are two layers of 4mm plywood.

Here the first layer is being glued down.

After the first layer is on, a second layer is glued on top.

The joints are staggered.

I used a notched spreader to apply a thin coat of thickened epoxy.

Additives are used to thicken the epoxy to a consistency tailored for each job.

There are at least a half dozen additives that can be used. Phenolic microballons give the mixture I am using the brick red color.

The second layer needs to be held down firmly and evenly to make a nice epoxy sandwich.

Staples, clamps, screws, weights, whatever can hold the sandwich together.

The reason for using two layers of plywood is that up near the bow the bottom panels begin to bend quite sharply.

A single thicker layer of ply would not be able to make the bend. Even the 4mm plywood takes a good deal of force to take the bends near the bow.

2009-06-30T16:53:00.000-07:00

Keel, keelson, keel batton, all have specific boat building definitions. We do not need to shave too closely here. I am just talking about the backbone of the boat.

The keel batton for Skorpa is 1 inch by 3.5 inches and 20 feet long. It runs from the stem to the transom.

Skorpa's bottom has a shallow V at the stern that steepens sharply as you near the bow.

The keel batton must have a bevel that matches this angle shallow at the stern gradually at first than quickly getting steeper at the bow.

To creat this bevel I first cut notches every 2 feet along the keel that matched the bottom of the hull at that point.

Next I used a batton to draw a fair line that connected all the notches.

I then made saw cuts down to the line and knocked the wood out with a chisel.

The idea is to get rid of the bulk of the unecessary wood without going below the line.

Then a sharp plane eases the wood down to the line.

More or less.

Here the keel has been mounted back on the jig.

Way in the background you can see the first hull panel in place.

They are next up.

Back to the Stem

2009-06-29T04:58:00.000-07:00

The stem is this L shaped piece of wood, rectangular in cross section.

Way back in April I laminated the stem and mounted it on the jig.

I put so much work into laminating the stem I was a little reluctant to start hacking into it, but sooner or later you just have to do it.

The stem needs to be beveled to a point at an angle that varies all along its length.

The stem is more pointy in the middle and a little flatter at its ends.

How you shape the stem to this angle is one of the mysteries of boatbuilding.

Battens are used to attempt to find the bearding line.

A lot of this you just have to figure out on your own.

Notches are cut into the stem from the bearding line to a center line drawn down the face of the stem.

The inwale and side stringer are set into notches cut in the side of the stem.

I think building a stem is a little like singing on key. You do not know for sure that you have done it correctly until after the note is sung.

Fortunately we have music editing software and epoxy.

The stem is attached to the keelson. The keelson needs to be faired as well.

The keelson is longer, but it is much less painful.

The stem looks pretty good but I won't know for sure until I try to fit the plywood hull panels.

Next I will fair the keelson.

Then it is on to attaching the plywood hull panels.

Transom on the Tangent of 3 Degrees

2009-05-11T18:38:00.000-07:00

Here you can see the transom hanging on to the jig and the keel coming in at more or less a right angle.

The tangent is equal to the ratio of the opposite side over the adjacent side of a right triangle.

Right now we are at 2 inches divided by 39 inches or about 2.9 degrees which is probably way close enough.

The tangent of 3 degrees equals 0.0524077793.

In the plans the designer specifies that the transom should be raked forward 3 degrees. Now I have a suspicion that when Graham was building the first EC 22 Southern Skimmer that he just tilted the transom in a wee bit and let it go at that. He could not really write that on the plans so he put down 3 degrees. Now I am going to spend an hour or two trying to set the transom within a couple of minutes of 3 degrees.

I know the stem of a boat can be difficult. The stem is often curved, it has rabbits, and bearding lines and plank landings. The stem can be complicated but a transom that is pretty much just a flat board stuck on the back of the boat. Right?

Well not quite!

Checking to see how the matched halves of the transom fit the pattern.

Here I am separating the halves and laying them out on the full size drawings. Hmmm any differences between the plywood and the drawings are due to humidity induced paper distortions.

Checking to make sure that I am keeping the edges of the transom square as I plane them down to the lines.

I clamped two pieces of plywood together and cut out both halves of the transom at the same time. I cut just outside the line using the circular saw set to a very shallow cut. Then I used a sharp plane to bring the pieces just down to the line.

I transferred the curve of the transom from the plans to a 2x8 that will support the transom on the jig and maintain the specified arc.

What Knot

2009-04-25T18:10:00.000-07:00

I had two pieces of wood in mind for the keel. 3.5x1x20. One piece was free of knots but a poor grain orientation. The other piece has a nice flat grain but a knot or two. I decided the knots were too small to matter and went with the nice grain.

I waffled awhile.

Then I finally took a saw to the board and cut the knot out.

This kind of angled cut is not easy to make.

The saw roughs out the shape.

The plane brings the slope down to the lines and corrects any misalignment.

Many boatbuilders use an 8:1 scarf. The Gougeon Brothers recommend a 12:1.

The lower the angle the more difficult the scarf is to make, the more you shorten your board and the stronger the joint.

I went with a 10:1

The second photo shows the rough cut.

Then planing.

And the final fit.

Now with a little glue I will have a keel with nice grain and no knots.

The stem

2009-04-25T17:50:00.000-07:00

The plans call for the stem to be made from solid stock. A full size pattern is included for cutting out the stem.

I decided that I would do a laminated stem.

I used the pattern to determine the shape of my mold.

Instead of just cutting out my mold I made one extra cut and this gave me three pieces.

The inner piece is the mold for the stem. It ties into the rest of the jig and helps to make it rigid. The holes are for the clamps that I will use to pull together the laminates.

The middle one represents the stem.

This came in handy because all measurements in the plans reference the forward end of the stem.

I think the outer piece will be useful when I begin to shape the laminated stem. I will be able to hold this piece up against the stem to insure that I shape the proper curve into the laminated stem.

I will post some more when I actually glue up the stem.

The stem is made up of 14 strips of wood each about 1 1/2 inches wide 1/8 inch thick and five feet long. The strips have to be thin so they will bend around the curve of the stem without breaking.

The first photo shows a dry run. Clamping the strips in place without epoxy gave me a chance to work out how I would be able to get all the strips in place. The strips were a little difficult to get in place the first time. They resisted taking the sharp curve, but after they spent a day clamped into position they got used to it. They went together much more easily the second time.

Here the epoxy has been spread on each strip and they are clamped in place.

The temperature in my boat shop was 55 F. The epoxy needs to be a little warmer to harden properly. I made a little tent and put a lamp under it.

Selling Out

2009-04-21T11:45:00.000-07:00

I have been struggling with decisions that need to be made about which brand of plywood to purchase and from where. Does the BS1088 standard mean much anymore? Does Joubert still make a good product or have their standards slipped?

I sold my Whitewater Kayak so I could buy some sitka spruce for my mast. What will be next?

Warning

2009-04-20T10:42:00.000-07:00

Just between you and me I only about half way know what I am doing. Some of the information in this blog could be useful some could be down right dangerous.

Be careful.

Joe

Pendulum or Plumb bob

2009-04-19T18:15:00.001-07:00

The molds have been cut out. Now I am erecting them on the 2x6 frame. Each mold should be plumb and perpendicular to the long axis and the correct distance from the bow. Phew.

All the molds are in place.

You could say the jig is up!!

Resources

2009-04-19T17:48:00.000-07:00

Well I am having difficulty getting my text to match with the photos. This is one big learning process.

Some of my resources.

In case you didn't recognize him that is Graham Byrnes the designer.

The book is the Gougeon Brothers on Boat Construction. Lots of detailed information on the combined use of wood, epoxy, and glass fiber in boat construction.

And of course

http://www.messing-about.com/forums/index.php?board=2.0

In the shop.

2009-04-19T17:24:00.000-07:00

The piece of plywood is a cutoff sled. It helps me make accurate cuts.

Finger boards hold the board securely and save fingers.

Using the hand plane to make the 2x6's straight and equal.

Good Enough.

Getting wood for a boat.

2009-04-19T16:49:00.000-07:00

There are lots of ways to get wood for your boat. A friend lent me her sawmill.

Some nice wood but a lot of work. I am lucky I still have all my fingers and toes. It is very dangerous work.

Back in Rhode Island

2009-04-19T16:33:00.000-07:00

It is April 19, 2009. Sally and I are back up to Great Island at what used to be her parents home. The house is located near a salt pond, with lovely views of the water from two sides of the house. In the garage I am building my boat. I spent several days cleaning out the garage and fixing shelves and racks to organize my tools. Then I ordered four 2x12's 24 feet long. They are construction grade douglas fir.

I am trying to plan how and where I will cut the boards to get the lumber I need for various parts of the boat. I am trying to work around the knots and grain imperfections of my less than top grade lumber.

Next I cut one of the 2x12's in half to form the base of my jig.

Building a B&B Yacht Designs EC22

2009-01-10T18:06:00.000-08:00

I want to chronicle the building of my boat. An EC 22 designed by Graham Byrnes. This is a 22 foot long sail boat constructed of marine plywood covered with epoxy and fiberglass.

I have been enchanted by this design ever since watching its development two years ago. I have tried to steer myself in the direction of more sensible designs, boats that would be easier to build and perhaps a bit more forgiving to sail. The Belhaven or the Micro or there are dozens of others. I always come back to the EC22.

http://www.bandbyachtdesigns.com/