Tag Archives: lamination

Caledonia Yawl Project: Installing the knees to the thwart

My next step for the forward compartment was to glue in the perimeter batten to hold the edges of the deck. I used small ribbed copper nails to hold down the battens in place while the epoxy set.

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I will leave the copper nails in as they won’t rust and won’t do any harm.

Then on to the knees that I had laminated a while ago, while I was in a laminating mode with the stems. I had enough off cuts of fir laminating stock to do the knees at that time. But since I’d just run the through the thickness planer when I had rented one for another task.

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The knees were first smoothed with the 1/4 round over bit of the router. That all worked mostly well except on one outer corner of the curve where the wood likely under tension ripped out with the router. I had to then glue the ripped section back down and sand it smooth.  To fit the knees instead of doing a template, I first cut the base angle and then scribed the right angles cuts to fit it to the inner gunwhale. When I made that cut I was a little conservative and I had the plane it down a few times to get it to fit snugly. I then used one side as the template for the other side and it went much faster.

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I’m now just going to do a touch more sanding before I get on to coating it all with Decks Olje. A two part oil finish that creates an fairly easy to refinish gloss coating. I like the rich clear finish it gives. Since I’m not planning on having too much material with a clear finish (Gunwhale, knees, thwart, Centreboard caps and bulkhead trim) I’m not too fussed about the cost. (nearly one third more than the cost of Cetol Natural Teak finish or most varnishes).  I have hesitated with my final choice for a while but ultimately decided to give Decks Olje a shot because of the penetrating oil of part 1 and the ease of touching up. In theory if you keep on top of it you could just touch up abrasions indefinitely without having to strip it all down as you would with varnish. Time will tell if I’m happy with it.

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.