Thursday, June 24, 2010

Joinery


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.

Tuesday, June 1, 2010

Cockpit interior

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?