Excelsior, an Atkin 'Cruising Canoe'

[troy2000]

This will be my next build. It's a 21 foot (6.4 meter), two-masted, decked sailing canoe from William 'Billy' Atkin, drawn in the winter of 1933 for MoToR BoatinG Magazine (no, I don't know why they spelled it with cap's like that...)

This will be a pretty slow thread, because I'll probably be doing a bit at a time in between the honeydo lists and working. But I have the plans, and that's a start. Next step is to build a quick hull model out of poster board, to double-check my suspicion that it has too much twist in the double ends to handle plywood sides.

I'm leaning towards building it pretty much per the materials and spec's in the plans anyway, though. Over the years, I've found it's generally better to cook a dish according to the original recipe at least once, before trying to improve on it. And this would be a charming period piece with its lapstrake sides, copper rivets, battened bottomboards and canvas-covered decks.

However I build it, I expect it to sail on its ear a lot of the time -- and scoot across lakes in a hurry, anyway. I definitely won't skip the spray hood for the front cockpit....

The plans came from Atkin Boat Plans, and a copy of the original magazine article was included. With the kind permission of Pat Atkin, I've attached the entire article below; it's a much better introduction to the boat than anything I could write.

The scan job was done in a hurry and came out pretty sloppy; I'll redo it first chance I get. But meanwhile, I think that if you click on the thumbnails and then zoom in, the pages are readable -- even if they're skewed a little, and the bottoms clipped on a couple of them.

Troy

[alan white]

She'll be tender alright, but speedy with some movable human ballast aboard and no doubt a lot of fun, with some camp-cruising ability as well. I think she'd row nicely too, which I feel is something a small sailboat needs. With four oars, she'd be wicked fast.

[troy2000]

Originally Posted by alan white

She'll be tender alright, but speedy with some movable human ballast aboard and no doubt a lot of fun, with some camp-cruising ability as well. I think she'd row nicely too, which I feel is something a small sailboat needs. With four oars, she'd be wicked fast.

And don't forget the four 25 lb, rope-bound sand bags specified in the plans as movable ballast.

[alan white]

Oh boy... and a plank too, sticking out the side...?

[troy2000]

Originally Posted by alan white

Oh boy... and a plank too, sticking out the side...?

Well, if it has sandbags, I guess it must be a sandbagger. And if it's a sandbagger, it has to have hiking planks.

But I don't know where I'm going to fit the 13-man crew, when 12 of them aren't out on the planks....

[Landlubber]

...simple Troy, you leave em in the water at the end of the run and pick em up again for the windward mark.....

[troy2000]

Originally Posted by Landlubber

...simple Troy, you leave em in the water at the end of the run and pick em up again for the windward mark.....

All joking aside though: a few sand bags for movable ballast could come in very handy, to trim the boat with varying loads of passengers, ice chests and the like. Or the lack thereof....

[troy2000]

Nothing is ever easy...

Once upon a time when I was contracting, I had two 5' drafting tables set up -- one fairly modern one, with a metal frame and drawers, and a WW2-vintage one just like it, but made of oak. I usually left the plans for a current project on one table, and did my drawing on the other. Those were the good old days....[sigh]

To work on this project, I went out and bought myself a small drawing board, plus triangles and T-square to scale. Then I set out to draw each station to scale on some poster board, along with the profile, so I could put together a hull model.

Problem #1: the head of the T-square didn't lay flat along the edge of the drawing board. Staedtler Mars made the head from some sort of particle-board crap, instead of wood or metal. When they glued and screwed the T-square together, the pressure squished the head out of shape. So I had to true it up, before I could keep working. I was going nuts, trying to figure out why I couldn't draw the same line twice no matter how firmly I held the T-square.

Problem #2: the plans are drawn at a scale of 5/8" = 1' 0". If they make architect's or engineer's scales that read in 5/8'' scale, I've never seen one. That in itself was no big deal, unless and until I needed to scale instead of reading numbers. Which unfortunately happened right away, on station nr 2. Apparently Mr. Atkin had a moment of dyslexia when he was copying his table of offsets, because he transposed and mixed together the width measurements at the sheer and the bottom.

So I took time out to draw myself a scale in the corner of my poster board, and started checking every measurement as I went. Luckily, that was the only one he seems to have missed.

Update: I now have the stations and profile ready to cut out and assemble, but I got interrupted by little things like roof repairs and dentist's appointments....

I'm also now the proud owner of a full-sized pedestal drafting table, that adjusts from dead flat to vertical at the push of a lever. and it has the smoothest-working drafting arm it's ever been my privilege to touch.

I paid a hundred bucks for it at a yard sale, and I wish I had seen it before I bought the little board and T-square. Now my only problem is trying to figure out where to put it. My wife's rearranging and redecorating wiped out any space for drafting tables a long time ago....

I may just clear out one end of the motor home I stay in while I'm working, and set it up there. And I can carry the little board back and forth, or leave it to use at home.

[ancient kayaker]

I sympathize with the Tee square problem. When I got my first job I bought a very reasonably priced Tee square, beautifully polished boxwood (I think) with bone drawing edge, what looked like ebony edge on the head of the Tee. I don’t know what happened to it but now it would be worth its weight in, well ebony I guess. Same thing for my first slide rule ...

The 5/8'' scale problem can be solved by taking the plans to a copier and having them rescaled to - say - 80% to get ½" scale.

The new drafting table sounds great! Have to say though, drafting software is a lot more compact and probably more wife-friendly!

[troy2000]

Originally Posted by ancient kayaker

I sympathize with the Tee square problem. When I got my first job I bought a very reasonably priced Tee square, beautifully polished boxwood (I think) with bone drawing edge, what looked like ebony edge on the head of the Tee. I don’t know what happened to it but now it would be worth its weight in, well ebony I guess. Same thing for my first slide rule ...

The 5/8'' scale problem can be solved by taking the plans to a copier and having them rescaled to - say - 80% to get ½" scale.

The new drafting table sounds great! Have to say though, drafting software is a lot more compact and probably more wife-friendly!

I'll definitely have the plans rescaled before I start building; probably up to 1" = 1' 0" because I'm used to working in it. Meanwhile, my little hand-drawn scaling table works well enough for my purposes. But finding the mistakes in the table of offsets is a cautionary tale, for anyone who doesn't think he needs to loft a boat because it's flat-bottomed and doesn't have compound curves.....

The drafting machine is a 60" by 37 1/2" Vemco track machine -- worth several hundred dollars used all by itself, if ebay and craigslist are any indication. And it's on a very nice Hamilton pedestal table.

Yes, I know CAD works well. But I like to touch and feel a drawing while I'm making it, step back from the table to get an overall view, casually scale any and every little part of it, etc. And CAD won't draw directly on big heavy slabs of stiff poster board, either.

edit: the drafting machine, like the table, is 72", not 60". Somehow I translated 6 feet into 60", instead of 72".....

[ancient kayaker]

Originally Posted by troy2000

... finding the mistakes in the table of offsets is a cautionary tale ... And CAD won't draw directly on big heavy slabs of stiff poster board, either.

That's actually reassuring to know because I was never able to match one particular offset point from a set of Wee Lassie (J. Henry Rushton ~1895) in my CAD adaptation.

I plan to have the plank developments enlarged by photocopying - a local house can do any length, about 3' wide. I won't get it done until the day I cut wood, so the paper doesn't have time to change dimensions! I will glue the enlargement to the wood using the temporary spray-on stuff from the local art store and just cut to the line. Perhaps I should ask for prayers ...

[troy2000]

Originally Posted by ancient kayaker

That's actually reassuring to know because I was never able to match one particular offset point from a set of Wee Lassie (J. Henry Rushton ~1895) in my CAD adaptation.

I plan to have the plank developments enlarged by photocopying - a local house can do any length, about 3' wide. I won't get it done until the day I cut wood, so the paper doesn't have time to change dimensions! I will glue the enlargement to the wood using the temporary spray-on stuff from the local art store and just cut to the line. Perhaps I should ask for prayers ...

Of course, if you enlarge the drawings that much, you'll be cutting to a pretty thick line....

[troy2000]

The plans for this boat call for 3/8" white cedar lapstrake planking, on oak frames set 21" (53+ cm) apart. If I decide to update the plans and use glued-lapstrake plywood instead, would it be reasonable to substitute 1/4" (6mm) sapele or other plywood?

This boat is still small enough to make wood prices basically irrelevant, unless I go absolutely crazy to prove some sort of point.

[PAR]

I've briefly mentioned it in other threads, but most buying Atkins plans will be disappointed, for several reasons. One major issue is they print the reproduction plans on 20 pound bond, which is fine for a letter to aunt Millie, but absolutely sucks for accurately scaled drawings. You see the paper has a grain, just like wood and it stretches disproportionately (with environmental changes), so much so that a 1" to 1' scale in one direction will not be at the perpendicular.

Considering her displacement, 100 pounds of ballast isn't enough to be concerned about, though if tossed up onto a rail during a race, could make a big difference. If you do glued lapstrake, she'll be light enough to want 200 pounds, possibly more.

Glued lapstrake is an option, you can toss the frames and likely a number of other elements too. If you use 1/4" Ocoume instead of Sapele, the weight will be about the same as the solid cedar stock. Of course displacement is still going to be setup for the weight of the solid stock and framed version.

This was intended as a developmental class and I don't know much of it's history, you can bet Billy took an active role at producing a viable candidate for the 'round the buoys crowd. The frame spacing suggest this. It would also be a good idea to replace the whole of the bottom planking with plywood. 1/4" if heavily sheathed, 3/8" if none or lightly skinned. The elimination of the little bottom plank battens alone, will reduce the weight of the boat quite a bit. If it was me, I'd use 1/4" topside planks with 3/8" bottom. I'd lightly skin the bottom and the lowest strake, say with 4 or 6 ounce cloth.

Also with modern materials and techniques (birdsmouth, aluminum or a combination) you will not need stays for this rig. I recently built a cat ketch of the same total sail area. It was unstayed and used sprits, rather then conventional booms, which saved some rigging too. The masts I made had aluminum tubing lower sections, with a birdsmouth upper portions. The resulting, fully rotating, 19' 8" masts (mainsail) weighed about 12 pounds, before I attached a 5/8" sail track and other hardware. Drop me an email if you want scantlings for a birdsmouth or combination aluminum/birdsmouth sticks for that boat.

[masalai]

Sounds good, Looks good... Have lots of fun ... in the build and sailing...