Hail, Voyagers,

A metaphoric pile of sticks, that is. Precisely, if you had a given amount of materials, how much boat could you build?

Specifically, how long, wide, and high for any given type?

What I’m assuming is that all the craft are made by the same designer using the same, or very near the same, construction techniques.

As an example, I’m thinking I could build a 24’ proa with about the same materials as a 16’ catamaran. The proa would have longer overhang in the bows and relatively less waterline length, so that LOA figure takes that into account. Also, I’m posing the cat as one you could sit inside, say with 18”-20” wide hulls—not a racer, but a little cruiser. Neither would have cabins. The proa’s vaka would be the same width. The cat’s crossbeams… do you call those akas too? ...would necessarily be heavier, and I wouldn’t go for too wide a beam, say 6’ on center. I figure the freeboard would be slightly higher on the cat, but with care, she could still have sweet lines. My favorite ancient designs for proas all tend to have rather small amas with rather narrow… what are the words, bridge decks? ...way out, so I’m thinking maybe a cl-cl (nodding to Sven 😊)that hovers near 50% of the vaka’s LOA. Certainly, the proa would have a buoyant sponson, maybe the little pontoon type like I saw in the Hawaiian racing paddlers.

What do you think? Are these numbers sensible?

I imagine this as a sort of competition between my own boats. But how would it work out with your boats? See, I’m limiting this. It’s really rather meaningless to compare different types by different designers with different design goals.

With mine, I’m imagining these boats as easy to handle, sturdy, and with lots of reserve buoyancy because my experience shows that little party boats like these do tend to get overloaded, so I want them to be safe and strong… “Kid safe,” if not “drunk fisherman safe,” if you will.

I would assume a fairly conservative sail plan, so they don’t get whomped on if the wind suddenly blows, and I’d settle for less than ideal light air performance because in those conditions I’m more interested in daydreaming or chatting with my shipmates than squeezing out every fraction of a knot.

I wonder, could the cat carry more sail? About the same? Less? If they are the same, then the proa would smoke the cat in everything but a tacking dual. Furthermore, the proa would have near equivalent cargo capacity. Some would be lost due to the need to keep the weight nearer the center of the vaka, and some would be gained due the lighter structure overall.

But honestly, am I near the mark? I just don’t know. The only way I know how to figure these things out is to build small scale models and test, test, test.

Last, I figure a tri would be between the two. A little longer than the cat, widest beam overall of the three, a little roomier main hull, and lighter structure than the cat.

A very frustrating thing for me is I have a very hard time figuring out how much sail any boat can carry. If anyone can suggest some resources for figuring that stuff out, I’d be much gratified. I’m looking for some rules of thumb guidelines, but I can see that I’m gonna have to get more technical. I don’t mind. The prize is worth it.

Be well,
Rick

There are two yardsticks to pull out for guesstimating sail area.

First is straightforward power to weight ratio; for multihulls the usual yardstick is Bruce number arrived at by dividing the square root of sail area (square feet) by cube root of displacement (pounds). If the resultant number is around one you are likely to be underpowered unless prevailing winds are high. Above two you probably need to shake out your wetsuit or drysuit.

Second is the ratio of sail area to wetted surface, which is a pretty good indicator of ghosting capabilities. Two and a half or three square feet of sail area to wetted surface is probably in the ballpark.

Take it all with a liberal dose of the salt shaker, there are a lot of other variables and there are a number of reason there are a multitude of different rigs around more importantly why the great majority have ways to reef.

FWIW P52 sailed with rigs from a 40 s.f. trysail to a 160 s.f. crabclaw, the best all around was a 48 s.f. boomed jib.

cheers,
Skip

Hi Skip,
What is that proa in the photo with your post. That’s a good looking boat. Can you point me to more photos?
Regards,
Russell

Thanks Skip,

That was super. Just the kind of dead reckoning I was looking for. At least I’ll be able to figure out how big a sheet of paper I need to draw a plan! I do understand that we must modify all that with a lot of other variables.

But the problem I keep hitting is when I’m doing something that doesn’t give pre-existing configurations to copy. Then I have to have some sensible starting point, even though it will probably be a point of departure.

Best,
Rick

Hi Russell,

Thanks for the interest, I’m honored, a lot of this is indirectly your fault, Starting with WB#83.

A short video
http://www.youtube.com/watch?v=iVoVP5ozj4I

There’s a link to an article in the Community/Introduction about P52 plus it’s probable successor Nomad when a few things shake out rig wise.

cheers,
Skip