Low-speed sailboat hull

Haven't thought about that. I have no idea, actually. Maybe on top of bow deck, protruding outward along centerline of the boat, more or less. I could arrange something for them to hold against. Not much for looks, but I can't think of a better solution.

 

Maybe you should do a bit of a mock up with MDF or whatever and see how the whole thing is feeling.

 

Sorry, what is MDF? You mean that I should make a model (because I plan to do that as soon as nobody else on this forum will have any critique for my design )

 

Fibre board stuff. Falls apart when it gets wet. Often used for cheap interior door skins or packing sheets. Good for mocking stuff up at full scale to see how it feels. Also makes excellent boat patterns.

 

Ah, yes, I know. Well, it would certainly cost quite a bit, and still labor intensive... Not sure I'm up for it.

Wouldn't it be easier to make a scale model? Something like 30cm long (1:10).

 

Yes, but you can't sit on a scale model, or at least not without nasty cracking noises.

 

Well, I'll have to take that risk! I mean, building the real thing without siting on mock-up first. I don't think that sitting will present a big problem. But I should first design the grating sharpii2 suggested. Not sure how can I make it fixed in the boat (so it won't float away) or light enough so that it can be a part of the boat.

NoEyeDeer, do you see any other potential problems with this boat? Any more reinforcements I should make? Right now, dry weight reads 25kg, which is on the limit, so I hope nothing principal is missing. What about daggerboard case flooding I asked earlier?

 

Anyway, I didn't mean you have to build the whole thing at full scale, but if you rough out some of the important elements (deck width and height, backrests or whatever) at full scale, using whatever you have lying around, it should give you a better indication of how it'll all work in practice, and if there's anything you should change.

As an example, when designing a comfortable passenger seat for my rowing boat, I did a quick mock-up out of various offcuts, my router table, and an old bed headboard. Played around with it until the angles felt really comfortable.

 

Can be fixed in with turnbuttons, or shock cord and a hook, or just tied to the boat with a lanyard.

50mm above the maximum waterline is probably ok, although you might get a bit of water slopping into the boat in a chop if the board to case fit is loose. A rubber gasket around the top of the board could help with that.

And I'm assuming you know enough about structure to figure that out yourself.

 

All right, thanks for suggestions. You've been very helpful, I really appreciate your effort

I will turn now back to the sail. In the meantime, if you have any additional ideas, or if anybody has any more insights into current design, please do tell.

I hope I'm not taking too much of attention here. This thread is getting big.

 

It's a boat design forum. You're designing a boat. I think people will just have to put up with it.

 

Nicely put. It's just that some people don't write anymore, like Petros, Skyak. I wonder if they don't agree with the design path I've chosen, or they just wandered off to help other people here.

 

Since I last looked in your boat is starting to look more and more like the design I posted in post 92!

I think your centreboard case is too low. Also, I think your boat is too small. Have you tried putting some humans in there? I would also suggest doing a full size mockup, can be very rough.

Why not have the sides where your back leans against on an angle? That would be more comfortable. You may not need the stern buoyancy tank with the side tanks. This is exactly how the boat I posted in post 92 is layed out.

That boat also has very light floorboards. Basically there are a couple of very low frames (maybe 60mm high or something) which go all the way across the boat. Between these are styrofoam blocks. On top of the styrofoam are some pieces of 4mm plywood, which are screwed into the frames.

I should add that that boat has a 4mm ply bottom, which is reinforced with internal stringers which are about 20x20 mm. The styrofoam lies on these stringers, which means that water can freely run from underneath. This mean that water is not trapped between the foam and the hull, which would cause rot.

 

Yeah, you're right, it's getting very similar to what you posted...

I can increase the height of daggerboard case, but why do you think it's too low?

I cannot make this boat any larger due to weight limit. Right now, this design weights 25kg dry. With epoxy and stuff, it will weight 30kg. And that is my absolute limit.

I could make these sides at an angle, but it would reduce space inside somewhat. I don't see why it wouldn't be comfortable at ~100° angle, just like now...

Stern buoyancy tank was suggested by sharpii2, if I remember correctly. I liked the idea because with watertight hatch, it would provide dry place to store things. It also adds structural integrity more than side decks extended up to transom, but most important reason for this design is that if I extend side decks up to transom, it will require larger pieces of plywood, more scarfing, etc. Complicates things.

Idea with styrofoam is good, but you see, right now, in my design, I'm already at weight limit. I cannot add plywood of such dimensions for double floor. I'm still thinking if there is a easier, less weighty solution.

 

My 2c: either get your buoyancy from bow and stern tanks, or from side tanks. You don't need both if you're trying to keep it light. Pick one solution and go with it. Either will provide heaps of strength to the boat if done sensibly.

If you have no stern tank and extend the side decks to the transom, you'll nee more ply for side decks but none for the stern tank. Overall amount of ply used: about the same. Scarfing is easy, so don't worry about scarfing. Just go with the best option.

If you want a grating to sit on, it doesn't have to be permanently attached to the boat. You can remove it to save weight while heaving the boat up onto your roof racks. Same for oars and other bits and pieces.