Beachcomber Dory Planked Half Model by Jim Cricket - 1:8 scale - from The Dory Book - Finished

[Jim Cricket]

I’d like to recreate the build log for a planked half model that I posted a few years ago on another forum (not a model forum). I’m rewriting some of the text, and copying and pasting some of the text from the previous post. Pardon me if it sometimes appears a little disjointed.

 

I've long been fascinated with the Swampscott type dories of Boston's North Shore, and I have considered building one out at my boat club. Years ago, I drew up a portrait of the sail plan for the Beachcomber, an exceptional boat from William Chamberlain's shop in Marblehead. I'll get bogged down if I try to describe it all here, so I will refer you to an article I wrote for my club newsletter.

http://jimluton.com/dorymod/beachcomberarticle.pdf

 

 

Below is the cover of a nice book, with Chamberlain's beachcomber on the cover.

 

 

The lines, table of offsets, and construction plans for this boat are published in John Gardner’s “The Dory Book”.

The half model is set up with half molds on a flat board (1/8" poplar ply), sawn to the boat’s profile shape, that represents the hull centerline. That profile shape is then mounted to a piece of MDF to keep it flat.  I used 1-1/2" = 1'-0" as a convenient scale. The model is a manageable size (the 21' boat is about 32" long), and scale planking is relatively easy to come up with. 1/2" planking translates to 1/16". For this I used a sheet of 1/32" aircraft birch, which I cut in half and vacuum bagged together to make a 1/16", six ply sheet. The molds are cut from 1/8" Italian Poplar ply. The 1" thick transom is 1/8" mahogany, etc. etc.

I already had the body plan drawn to scale in the computer, so I printed out the individual sections and glued them to the 1/8" ply mold stock, then cut them out and faired them on a little belt sander table.

The molds and transom are each glued to the profile board in their respective positions, corresponding to their position on the lines plan. I used cyanoacrylate for this, as for the whole project. I mounted the profile board to a piece of MDF with an "L" shaped block on the back to facilitate clamping in the vise in various positions.

 

 

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I'll stop here for now, and pick this up tomorrow. Time to work on the sharpie.

Thanks for looking!

Cricket

 

[Jim Cricket]

Dories have a narrow, flat bottom, usually about an inch thick. I used the 1/8" poplar again for that, gluing it onto the molds and then fairing the edge in a long, winding bevel to match the angle at each mold. This is just like it would be done on the full size boat.

Once the bottom is on and faired, the planking can start. I used bristol board to make plank patterns, wrapping a strip around the molds and marking off the knuckle locations from underneath. You have to be careful not edge set the pattern. It must lay flat and "normal" on all the molds. After marking the knuckles, I measured the widths to the inside bevel of the bottom at each mold, then faired the lines with my spline and ducks. The expanded shapes of boat planks can be surprising.

Once happy with the pattern, I traced it onto my planking stock, cut it out, faired it with a block plane, and glued it on the molds. It's a challenge working this small, trying to figure out ways of clamping things to a small, fragile setup. I ended up just starting amidship, and gluing a little bit at a time, holding it all with my hands til the glue set, then moving on. I've lost quite a bit of skin so far to the cyanoacrylate.

 

Each plank is beveled once on the boat so the plank above lies fair, with a close fit, making contact with 100% of the bevel. In the extreme ends, gains are cut to let the planking lie flush at the stem and transom. This was done with a knife and small chisel. My rabbet plane is too big to do any good here.

This was my first model, and I was surprised at how thick and workable a 1/16” plank actually was.

Each plank was patterned, cut out, then glued on the boat. I installed small blocks inside the model, so I had something solid to screw into to mount on the presentation board.

Before the sheer plank went on, I fit a deck cap to close the model off.

I fit a spanish cedar rubrail, tapering it in height and thickness in the ends, to lighten the sheer visually. As with full size boats, I sealed the rail with shellac before installing.

This keeps the bright work cleaner while gluing and painting the model.

Once fitted and trimmed, I painted the hull with white casein paint. I like the soft surface it imparts.

Then, with the model propped up exactly level and parallel with the waterplane, I made a little jig of blocks at the right height, and scribed a waterline on the boat.

 

 

The bottom was painted with red casein, and when all was dry and sanded, I waxed the hull, and mounted it on the presentation board. That piece of oak was a curbside dumpster find. An old oak dresser was being thrown out, so I nabbed parts of it. Nice flaky quartersawn oak.

These planked half models are relatively quick to make, and look good. I think there is potential for a good exploration of hull types. It’s also a good exercise in lining planks.