Tag Archives: boat building

Caledonia Yawl Project: Thwarts and bulkheads

This summer I’ve been working on getting the interior of the hull completed.

I started with the thwart and and thwart cleats.

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Thwart cross-section https://flic.kr/p/K5ndVX

I glued up some 3/4″ reclaimed mahogany that I found on craigslist that had been pulled from hold Vancouver home window and door frames. It was not quite wide enough or thick enough. So I glued two pieces on edge and then onto a 1/2″ douglas fir boards. I then planed it down to 1″ thick which is just over the plan specifications of 7/8″.

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The Thwart Cleats

The Thwart cleats were a complex piece to put together with a bevel on top of the curve of the hull to shape. It was also fun to figure out how to place it level and just in the right direction. But spending a little extra time on this I believe will bear fruit in the long run as it is such an important structural part.

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The next step is to install the forward bulkhead and the deckbeams and kingplank. This part is also confounding me as the plans show the deck following the topmost lap between the sheer strake and the strake below. But this seems to create a curve that does not match the curve of the deckbeams specified in the plans. So essentially I have a choice of which path to take to reconcile the plans to the real world.

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scribing the shape of the deckbeam on reclaimed wood.

For the deck beams I needed more wood, so I made a trip to Jack’s New and Used in Burnaby and found some good old Douglas Fir door frames that were 1 1/4″ thick. this gives me a nice dimension to work with to shape the deck beams.  The old Douglas Fir is now super hard and maybe a little brittle but also very solid. So I’m hoping it will result in a durable choice.

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And again there are a lot of bevels to line up on this piece. But I’ve been taking my time making good templates first and then transferring the shape and angles to the final stock I want to use in the boat.

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I’m close to getting it right, a little more trimming and it will soon be ready for gluing.

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Caledonia Yawl Project: flipping the boat

Last night I put the call out to a few friends to help out to turn the boat over. I rigged a long 1/2″ braided line to the rafters.

Then I crawled around under the boat trying to find all the brackets I had set up to hold down the keelson. I also removed all the braces for the station molds.

Then under a torrential downpour with the corrugated tin roof making a racket we got ready to lift the hull.

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It unstuck fairly easily, and with 6 sets of hands we lifted it without any trouble. We then went along while the line held the boat up to remove all the station molds.

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It was amazing to finally have an unobstructed view of the inside of the boat for the first time.

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Then we lowered it down and spun it while it was still held by the line just above the strongback.

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Here is a short video shot on my friend Dom’s go-pro camera mounted in the corner.

There is a fair amount of scraping ahead of me to get all the spots I was not able to clean up that were behind clamps.

I’m looking to figure out who supplies shavehook scrapers or contour scraper in Vancouver?

Then I think I may round over all the edges of the plywood inside and apply a small fillet of epoxy to help the paint hold better and avoid voids where my clamping was less than even.

 

 

 

Caledonia yawl project: priming the hull

Today was a turning point. I put a roller in a tray of Cloverdale paint alkyld primer and started to hide the wood.

the first few strokes of primer

Yesterday after consulting Ian Oughtred’s guidance on whether or not to paint the hull with epoxy before painting. He is adamant that it is not a good idea. So I decided to go straight to priming the hull.

My next resource is the small book by Joni Blanchard “Tricks, Cheating & Chingaderos” a collection of knowledge and tips for varnishing and painting wooden boats.

I liked her suggestion of wiping down with denatured alcohol to try and have the surface as clean and dust free as possible. The only problem is try finding denatured alcohol in Canada. You won’t find it in the paint section of the hardware store. I found it as burning ethanol for garden fireplaces and stoves at Rona called Bio light. Otherwise the other option was marine stove fuel or 99% isopropyl alcohol à the pharmacy. But that only comes in small containers.

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I also found a neat little tool to mark the waterline in such a way that it would remain visible under the paint.

It comes from our sewing kit. And leaves a nice little series of small bumps.

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Caledonia yawl project: Making more sawdust

The process of cutting thin strips for laminations is a reductive one. As I don’t have a band saw, I’m using a table saw with a blade that is just shy of 1/8 thick. So for every 1/8″ thick strip I cut, I loose as much in sawdust.



I have just two more 2×3 boards to rip and I’ll have everything I need to glue up the bow and stern apron and stem.

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.