Simple Proa

[amish rob]

Me? I don’t know. Best guesses are what I got.

That’s why I posed the question. I want experienced feedback, if there is any. Guesses, conjecture ps and thoughts are invaluable, too, because I have no idea. I’m working with 100% “book” learning.

The reason for some of these exploratory lines, though, is the nature of the build. This is not pick what’s best and do it proper-like; this is catch as catch can, Rocketships From Dirt type building, and I have no IDEA what wood may present itself for cross beams and platform, yet.

I’d like to explore all the options with the smart kids before I just go ahead and start doing stuff.

Truth be told, that damned home made trimaran thread had me thinking about folding beams.

[amish rob]

Nothing has happened on the boat. Much actual work to do, and much heat have precluded boat work.

Much heat.

The next steps involve epoxy work, so I have to wait for this heat wave to pass.

Meanwhile, I just look at the model, and the hull, and look some more. I keep thinking about the crossbeams and platform, too, and how best to build that assemblage as lightly and strongly as possible with the available resources.

I think this boat is being born in the spirit of the originals in that way, at least; I am making the best of what I have to make the nicest boat I can with it. I hope, anyway.

I continue to ponder three crossbeams (or maybe four even!), if only because the platform needs to be strong enough to support all the weight of the sailor(s), and the wider the span between beams, the heavier the platform slats need to be. And, that is the same thinking with the ama connection; an extra lashing is not that big a deal in relation to the benefits of having a better supported platform, for the same weight.

And, yes, I know what it’s like to lash stuff together every time you use it. It’s all guesses and compromises.

The real answer will reveal itself when I can do a few full size tests with mock-ups. Soon enough, I hope. We are due to get some habitable overnight lows soon.

[RFNK]

https://m.youtube.com/watch?v=cfd9Jitq7_o

[amish rob]

Yesterday, while shuffling the hull around my current paying job, I just kept noting some unfairness in the windward side of the hull; just some area where the bottom and side curves made a weird, harsh wonk.

The spreader stick slipped and as the beam shrank, the wonk went away...

So, the new beam at sheer is about 10cm less? I haven’t measured. The side panels look much more smooth in their transitions to and from pointy, and the whole looks much more cohesive.

Also, the weather may have broken, and if it stays this low overnights, I can start to tab this hull together!

[TomF]

Very fine.

[amish rob]

DFC2A772-7FE5-4218-846F-CEFE675705DF.jpg
This is the end... I’m not sure which. This shows the asymmetry and the tilt to the bottom panel well, I think.

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Yeah, I know, but the other end looks exactly the same. This is the side I had to remove the “wonk” from. There was a weird knuckle towards the end. Looks smoother to me.

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I’m going to use stems so I can screw the panel into something, as well as glue them. I think this will help keep the stem seam on the centerline, and it will give some meat to screw an outer rub strip into.

This is an absolute jackelope of a monstrosity, already.

[rael dobkins]

Now I get it, that's a hard shape to achieve.... I almost can't believe the 2 photos are the same hull.... Very cool bow and rocker.
That flat bottom will take a load!!! Looking good.
Finally back 2 it. Good Luck!

Keep Shunting bro.......

[amish rob]

Thanks, Yo! I tried very hard to combine a LOT of different desires into a very simply made hull. I hop it all works as planned. Hahaha.

I am finally able to contemplate using epoxy, again, so I’m messing around. The next few steps will be tabbing and gluing up the hull, so the heat was a HUGE factor in the delay.

Well, that, and actual work to earn money. Haha.

Baby steps toward a fall launch, I hope.

[Dusty Yevsky]

Looking like some excellent TLAR engineering!

[Liberty53]

Nice Work!

Looks strong and fast.

-Derek

[amish rob]

Thanks all.

Unfortunately, I think there has been a MAJOR problem occur with one of the hull panels. Not one of the main hull panels, but...

I don’t know, and, frankly, I don’t really WANT to know, at this point.

It may be bad. Like, start over bad... but, at least I won’t have to start form total scratch, if I do.

Now, off to ignore it for a few days, and come back with fresh eyes!

[amish rob]

I couldn’t ignore it.

There was a major failure in one panel. The inner ply simply broke apart, and the break spread outward. The panel is totally compromised, and would have failed completely except for the outer plies. I mean, the good news is, the stuff endured a failure fairly well. I guess that’s good?

It could have been a random weak spot or undetected (by me) void, or just a flaw in the wood... or, all the inner plies of this stuff are just pure garbage.

The literature says it’s gravy, but this panel makes me too doubtful. I may never know if the damned thing sails, now.

Insert seven minute long uninterrupted string of filthy swears here.

[TomF]

Bugger. Bugger.

[amish rob]

Well... the good news is I have some righteous templates.

I had doubts, and the ply wasn’t exactly what I ordered, but I went ahead, and I shouldn’t have.

Meh.

Dumb. Not my first time being dumb, either.

Life keeps lifing.

[jsjpd1]

Cool project Rob! Thanks for sharing it.

[skyl4rk]

Could you post a picture? I would like to learn what not to do from the failure.

[amish rob]

There isn’t much to photograph. There is a crack inside the plywood which allows it to bend along the internal failure.

A simple material failure.

The way to avoid it is to use good materials.

[amish rob]

Well, if I manage to sell a few more drawings, I may be able to to buy a few more panels and try again.

My dude found a good source of some nice 4mm ply, and has promised to eat it if it sucks when it’s delivered this time.

I stare at the model every day and dream...

[amish rob]

Not dead! This is not dead!

I have taken the time away to look back, and plan the second sortie. I will change a few things about how I put the next hull together, and I want to make a few changes to the rig.

I am also considering making the ama from glassed foam, which I THINK I can make lighter than the same sized timber and glass version; if it weighs close to the same I’ll be happy, because I will worry less about holing a solid foam ama.

As soon as I can procure a few sheets of plywood, I will start again.

Oh. I think the whole scull idea will stay hypothetical. In reality, the boat will like as not be paddled as much as sailed, and used as a swim platform as much as anything. As such, it will definitely need some paddles of its own, and if I make the paddles right, why, we could just use them as old school steering oars, too, eh?

That is all.

Until then, patience. And staring.
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[rael dobkins]

That Photo looks good bro, Foam ama? plywood spine down d middle?? surfboard style??? foam hulls kick ass, Sven Yrvind (has a youtube channel) builds some serious boats that go a very long way with foam.... I too am thinking of a foam future.

Keep Shunting, and keep building.......................................... ....................

[amish rob]

Yeah, Buddy! A plywood “t” to form the deck and spine of the ama, with foam glued and shaped and glassed.

I mean, if I’m glassing a light ply hull, may as well glass a blob of foam?

Plus, there is an insulating job coming up I may be able to pinch a few sheets from.

[amish rob]

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I want to change the rig a bit. This is a bit smaller than I had, and I think better for around here. I like the way the whole shebang balances on the model, so far.

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I made this cute little cup for the mast.

Which, the pause has allowed me to rewind on a few things. The extravagant deck has to go. On the real boat, I’m going to put the crossbeams parallel, and add a “spreader” beam at the ends, lashed between the beams, to brace against the back stay pulling the ends together.

I think I’m going to use the board with a dowel through it type ama connection, too. The one Gary mentioned earlier, and uses on his Waapa canoe.
Remember, Robert. Simple proa. Simple. Sim. Ple.

Near the main hull we can run a few planks/floorboards to sail from, and if we want to lounge somewhere, we can string up a hammock between the cross beams.

And, though the scull is appealing, we’ll like as not paddle the thing if there’s no wind. Since we’ll certainly have paddles aboard, makes sense to use one of them if we need steering trim, eh?

I am completely rethinking the shape of the side panels, too. I am thinking to add less cut in rocker, for a more subtle shape. I’ll try it out smaller to see if it even looks like what I imagine. Models is fun. And cheap.

Anyway. 3 steps forward, and 2 steps back!

[Gary Dierking]

Be sure that your mast can't jump out of that cute little socket. Lash it in place. Don't ask me how I know.

[amish rob]

Be sure that your mast can't jump out of that cute little socket. Lash it in place. Don't ask me how I know.

I noticed how easily it upsets as a model. Never fear! This cool guy wrote a book about these type boats, and he recommends lashings in the same place I read about cups and sockets.

[amish rob]

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Like this, maybe? These crossbeams are spaced about 2.5m, because it worked best and easiest to simply keep them where they were, deck wise and etc. I may change the spacing on the real deal, scooting them together, maybe to 2.2m or so? We’ll see if and when we see.
I just did all this with the stuff I already had, so it’s all to fit the junk I cut away.

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With some of these to secure the ama, it will be a lot easier all around. And wiggly in all the right ways. And, I came up on some nice, short lengths 1-1/2” hardwood dowel… life is funny that way, eh?

Anyway. I like the changes. Sometimes bad things happen for good reasons?

[amish rob]

I think I have shaken off the sadness of the materials failure, and I have located a source for suitable ply to retry. Not now, because it’s cold. For here.

I AM, however, making a new, better model, with all the evolutions built in to begin with, and from better materials. I want to change the way I build the danged thing, and I’ll test it on the model.

I’m also thinking very hard about making a foam ama. If I calculate it properly, the foam will cost less than ply and sticks, and the whole shebang will be lighter, to boot.

Which, if we’re paddling or sculling, a lighter ama would be nice, and a big, buoyant ama makes me feel happier for general use,
like swimming and paddling with dogs and kids.

Plus… there is also the crazy notion to stick a board through the side on one end to mount, say an electric outboard type motor. Then, I could, maybe, I don’t know, sling some solar panels around on the platform, say? Maybe I could motor about quite a bit that way, looking at bald eagles or white pelicans?

Anyway…

[Lugalong]

SOF for the ama gives you the volume with weight close to the foam thing, which is going to need some wooden structure in the way of at lest a stringer and stanchion/ connective to meet the cross beam /iako. Plank connective with iako inserted and tensioned by a lanyard (as per Dierking option) should work out with a SOF ama.

[amish rob]

Question for foam ama makers. Does the foam NEED the spine of wood? I’ve always thought the spine provided rigidity to the structure, like a stringer in a surfboard does.

I was wondering because with my ama shape, it would be pretty easy to cut out layers, like building a half model, and then just carve down to the edges and fair. If I spring the deck to the rocker I want, and just add layers, it would be simple.

I little more difficult, by virtue of a few extra steps, to add a stringer, but not impossible.

I’m really leaning toward the foam, as my bad math seems to indicate I can get the lightest structure for the size that way. Also, carving and glassing foam just sounds way better than a bunch of fillets or fiddly bevels on necessarily tiny stingers and clamps.

[rael dobkins]

Question for foam ama makers. Does the foam NEED the spine of wood? I’ve always thought the spine provided rigidity to the structure, like a stringer in a surfboard does.

I was wondering because with my ama shape, it would be pretty easy to cut out layers, like building a half model, and then just carve down to the edges and fair. If I spring the deck to the rocker I want, and just add layers, it would be simple.

I little more difficult, by virtue of a few extra steps, to add a stringer, but not impossible.

I’m really leaning toward the foam, as my bad math seems to indicate I can get the lightest structure for the size that way. Also, carving and glassing foam just sounds way better than a bunch of fillets or fiddly bevels on necessarily tiny stingers and clamps.

Never done it, but a full ply spine sounds easy and strong to me, it will also make a solid base for connecting akas. Garry knows best, if you can get hold of him....

Keep Shunting bro, BSY

[Gary Dierking]

Yes you can build a foam ama without the ply stringer. One of the greatest aircraft designers of our era was Burt Rutan. He designed some foam aircraft for the home builder. The shape of the wings was cut out of Styrofoam with a hot wire. Shallow troughs were sanded into the top and bottom of the wing to take layers of unidirectional fiberglass. For your ama an extra strip of uni top and bottom should do the trick. If you use carbon, it is so thin that you don't need to sand a depression for it. Below is a cross section of one of his wings.

[amish rob]

If my bad math works out, the materials will be cheaper and lighter for the foam, which is cool, and as I’m starting over, why not? Haha. It will also be MUCH less work than plywood. Harder to put in a dagger, maybe, but only slightly; especially if the dagger trunk is built alongside the center stinger before the foam is added…

I think a spine down the center would be nice, anyway, if only to use as a guide to help symmetry, end to end. It would actually probably be easier to assure the ama is symmetrical side to side if I cut the pieces for the layers in pairs, too.

Hmmm…. seems like an answer, eh? Hahahaha.

I’m going to do a few things differently this time, beside using better plywood.

[amish rob]

Yes you can build a foam ama without the ply stringer. One of the greatest aircraft designers of our era was Burt Rutan. He designed some foam aircraft for the home builder. The shape of the wings was cut out of Styrofoam with a hot wire. Shallow troughs were sanded into the top and bottom of the wing to take layers of unidirectional fiberglass. For your ama an extra strip of uni top and bottom should do the trick. If you use carbon, it is so thin that you don't need to sand a depression for it. Below is a cross section of one of his wings.

Oh, yeah! He’s from near here, actually, and I’ve seen more than a few of his aircraft. Excellent that you’d mention him. I figured as much, but I know there are folks here who have DONE stuff, and isn’t that the whole point of the place?

Many thanks, Yo. I was flipping through your book, again, and the foam ama part just GRABBED me this time. A did a little math with prices and weight, and I’m pretty sure I’m blown away. The savings should be fair, both ways, and there’s not that much more work glassing foam.

One day, I’ll get this dumb boat together and we can all see if it works! Hahahaha.