a beach multihull.

well, after the talk that got started in 'cats vs. tris' thread, i figured, hey, what kind of fun would it be to get everyone involved, in some way, with figuring out a 'best ideal' beach multihull.

i'm talking about a peewee boat, something you could make for the kids, or for yourself, for cheap, for fun, a real short-endurance boat, light, cheap, fair to excellent handling, stability, speed, and capacity. a boat that does a lot well, not just a few things excellenty.

not a boat you'd want to take on an adventure trip(though you could, if your balls clang while you walk about), but something you could easily take when you go camping as your get-around craft. i dunno about sleeping aboard, maybe if there's no suitable site onshore. but it can be done.

so, throwing out my thoughts:

i'm partial to a trimaran. really it's my bias, as they've always seemed more stable to me, and they are almost always faster. Cats have a lot of advantages though, so if it seems to be the better choice, i'm all for it. cats do have simplicity advantages that many trimarans lack.

construction technique: this should be something anyone can do. perhaps the same as surfboards. shaped foam, fiberglass skin. so solid hulls, no storage space in them. simple, sinkproof, lots of bouyancy just in case, and rather strong. this has solid pluses that just most other simple techniques lack. it can be done purely with hand tools if you lack a hot knife, and it's something a beginner can do. it's also fairly light. not as light as something hollow, per se, but still light enough for a small person to manhandle about.

size: overall, i don't think more than 20', and that's really at the outside. i'm more partial to about 16' for a beachboat, anything more gets to be a pain to get on top of the car.

collapsible: it MUST break down.

sailplan: i'm very open here, as everyone has their favorites. i've put together a few beach multihulls, ranging from two kayaks with a catboat set junk sail made from a tarp, to the rather crazy idea of somehow cramming three masts and triple foresails onto a 20-ish foot trimaran(as a note, you can get up and MOVE with a square rigged setup on a ultralight boat but you're going to be busy when you set sail even with a crew to help), and i'm partial to simplicity. i do note that a gunter has the advantage of letting you have a shorter mast, which is nice. but you can always square-sail it, like a viking boat... great for running dead downwind.

beyond that, i really can't think of much.


thoughts, anyone? feeling very open to ideas and opinions, and i'll see how it takes shape in CAD. once we're done, i think i'd be okay with releasing the drawings to the forum, kind of my contribution back.

 

There are so many cheap second hand beach cats at under 18ft that it would be difficult to build a boat for the same price, far better to just load them up ( it doesn't matter that it may not be as fast as the latest version ) and go and enjoy the sailing.

Now if you want to design a 22 - 24ft Tri that would be a far different matter.

 

i can do a tri in that size. about the tops i'd want to put together for cartop use would be in the 21-22' size. the upshot to doing that is that you can make the whole thing collapsible much easier, so that you don't have to take it apart. how many of those beach cats feature that?

rig preferences? 22' is enough to fit double masts if you're feeling brave, or a single sizable mast in a cutter rig.

 

http://homepages.paradise.net.nz/garyd/

 

good, but complicated to put together. i've been thinking along the lines of 'folds down', actually.

but some of those designs are quite nice. similar to what i cut my teeth on growing up in hawaii. there are a lot of echos of the style the 'tamanu' is modeled on in the bigger adventuring trimaran i'm building, it has a lot of hawaiian influence on the hull shape, the extremely fine entry and shallower wet surface.

but the boat's got a lot of what i think is missing, too.

but yeah, those are good. i'm still thinking collapsible, trimaran, solid foam, single mast, everything folds out and locks in place.

you know, clever.

 

You're 20 years too late. Ian Farrier's first comercial production tri was 20' long, used his marvelous folding mechanism and could be rigged and launched by me, and about a hundred other owners. It wasn't as fast as my previous Hobies, because it weighed a lot more, mostly due to the complexity. But it could carry four or five adults, floated in 10" of water, and was tough enough for white water and ocean surf! It could move out on a broad reach (this was before GPS) but it was much less likely than a cat to get into trouble in wild conditions. I see theres a 23 foot tri coming in from France that looks like it can outsail racing cats like the firebird. That will be a change after all these years. As far as I know there hasn't been a sub 24' tri that could keep up with same size cats in a very long time.

 

You mentioned a french 23 ft Tri, any links or names to follow up on

 

i've seen it. it's a little much. i'm talking about something cartop portable, that collapses into a package oh, three feet across? the mast(s) would fold down, not detach. and i'm looking for 6" or less of draft in my design.

something you could put on top of your volvo, drive down to the beach, set up, drag out to the water, go have fun with, come back, pack up, and spend less than 30 minutes doing setup and takedown(combined)

 

One of the things we're discovering stateside, as our petro bill is catching up to the price world wide is that moving the boat from the top of the car, I canoe a lot, to a trailer increases gas mileage, saves backs, and might increase the simplicity of your design.

Borrowing from the beach cats with their cat trax sand system would permit remote launchings.

 

This is a good observation, but it kinda needs to be looked at on a boat for boat basis. Depending on the shape and size of the hull(s), the roof mounting orientation and placement and.. a short list of other items which includes speeds driven. The mileage my not be compromised all that much.

Putting the boat on a trailer does not guarantee a free lunch on the wind drag component. The same issues of shape and size, as well as distance behind the vehicle, width of trailer and on and on, could actually make for more drag on the car.

Most cars have a fairly decent vortex thing going on behind them and that shed vortex is going to be running smack into the trailer and boat, making for a real dandy ball of screwed up air flow.

Actually, I'd like to see a 24' folding foam trimaran on the roof of a typical family car. I think it could be done with the right boat design and careful planning during the mounting phase. Security might best be served with a removable rack system at the front and back of the vehicle to keep the hull from torquing its way right off the roof in a side wind, taking the car's roof away as if done by a huge can opener.

 

I guess what you are really looking for is a disposable version of the Weta (see www.wetamarine.com ) or Hobie's sail equipped outrigger kayak. Perhaps you could do something with a folboat!

 

well, not disposable. and not really a kayak either. i don't really see a need for a cockpit for a beachboat. never have. just seems like something that's more or less superfluous.

but i'll say this, the weta's near what i'd want, just a bit smaller and less trampoline.

 

http://www.sailingcatamarans.com/pixie.htm