Spar Building

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.

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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.

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

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

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

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.