Tag Archives: wooden boat

Caledonia yawl project: the sixth strakes 

Today I started on the beveling of the landing for the sixth strakes. Before starting I laid them up in place to see how they landed and mark where I’ll cut the gains on the ends. It also feels good to get a preview of what it will look like.

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Cutting the gains on the very long sixth strake. Most of the gain is cut on the receiving fifth strake, (70-75%) but I like to cut the strake being fitted as well to leave a little more wood on both.
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The receiving gain all set to be glued up.
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The port sixth strake all whetted out with un-thickened epoxy before adding the thickening fibers West 406 & 403.
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All clamped up. It is 13-14 degrees C in Vancouver these days so it should set nicely overnight.

I was able to include my children with the removal of the clamps after it was glued up and they participated in roughing in the seventh strake on the starboard side.

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Removing the clamps the next day.
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Help with roughing in the seventh starboard strake.

 

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removing the clamps from the starboard sixth strake glue-up.

I’ll close this post with a little video of my daughter helping me with the removal of the clamps.

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Removing the clamps.

Caledonia yawl project: gluing the bow stem

When I ripped the strips for the bow stem I was not sure what the appropriate thickness would be so I played around with everything from 1/8″ to 3/16″ and up to 1/4″ most of my strips were 1/8″ thick.

Which meant that to create a 3″ thick stem I needed nineteen strips. Each strip needed to be buttered with epoxy and with so much surface area that turned out to be about 850ml of epoxy  or nearly a whole can. If all my strips were thicker I would have used much less epoxy. The lesson that I learned is that when laminating use the thickest strips that the mould will bear.

 

Nineteen strips of Douglas fir waiting for the epoxy

 

Then Fortunately Patrice came out to help me with the laying out of the stem on the mould.

a fair bit of epoxy squeeze out

Caledonia yawl project: Ripping Jig and other preparations for the stem and apron

To be able to get the 2″x 1/8″ thin strips needed to laminate the apron and stem I need nice clear (knot free) vertical grain wood. In my case that will be Douglas fir.

Last weekend I was able to find several 2×3 lengths that if ripped on its edge will give me 2.5″ wide strips that will give me the margin to plane down to the 2″ width specified. To do this you need to rip accurately, and the solution I found is to make a little jig that attaches to the table saw that should help yield consistent strips throughout the 8″ lenth. After each cut you move the fence over until the board stock rests against the jig guide wheel & repeat.

ripping jig
simple ripping jig with roller

I also went back to the lumberyard to get western red cedar to build up my centerboard and rudder. I’m doing this while the strongback is free of the boat and I have a nice flat surface. That way I’ll get all my laminations done at the same time.

I’ve borrowed from the Gougeon Brothers and tu Gurit Embh. publications on wood foil construction.  Ian Oughtred’s plans and instructions in “Clinker Plywood Boatbuilding Manual” are good but basic and as water is so dense small improvements in execution should have dramatic impacts in performance.

lamination plan for rudder and centerboars
Centerboard stringer design in “How to build rudder blades & centerboards” by J.R. Watson
Gurit instructions for cutting a Naca profile for a centerboard

Gurit’s guide also suggests that in testing stiffness western red cedar sheathed with three layers of unidirectional carbon fiber had a 67% gain in stiffness over just using mahogany.