Join Date: Mar 2006
Location: New England
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I'd think that a generalized rule for multihulls isn't really all that feasible, since there is such a wide range of variation on the designs...
First of all, you have two distinctly different platforms—catamaran or trimaran.
Second, you have very different design philosophies... on a trimaran, you can have a full wing deck design like an older Jim Brown Searunner, a partial wing deck like some of Dick Newick's designs, or a center hull only design, like Chris White's Hammerhead 54.
Same thing on catamarans... you can have a relatively minimalist catamaran with little or no bridgedeck ala Wharram's Tiki series, or you can have a low-bridgedeck clearance, high windage beastie with a nearly complete solid bridgedeck, like an endeavorcat, or a high-performance partial bridgedeck boat like a Gunboat 48.
For example, while a Gunboat 48 may have a fairly high cabintop, it is located fairly far aft on the boat, and doesn't affect the boat's ability to tack.
As to where to draw the line...it really depends on the boat, the way it is rigged and the sailor. Larger boats, by definition, are more capsize resistant and safer... but a boat that is too large for you to safely handle is just as dangerous, if not more so, than one that is too small.
I wouldn't buy a multihull that is under-canvassed. IMHO, this is a problem with some of the cruising catamaran designs out there... since they come with a relatively small sail plan. The problem with that is the majority of the time you're out sailing, you're generally in lighter winds, say 5-15 knots. With a deliberately under-canvassed sailplan, you'll have to motor in the lighter winds. That is probably why you see so many large charter cats motoring, rather than sailing.
You really need to have sufficient sail area to move the boat in light winds, yet have the ability to reduce sail down enough so that you're not over-canvassed in higher winds. In some cases this may be accomplished by rigging the boat as a cutter or ketch, rather than a sloop. It may also be accomplished by having more reefing points, say three instead of two, or deeper reefs that eat up more sail area with each reef. In fact, I'm thinking of asking my sailmaker to add a third reefing point to my mainsail for just this very reason.
While a multihull can have an impressive speed advantage over a monohull, especially over short distances, the overall speed advantage over long distances and durations isn't as great as most people would think. This is often due to the fact that you don't want to sail a multihull at the maximum speed it is capable of in most conditions, since that is a good way to end up pitchpoling or capsizing her. I've been out in 30 knots of wind, and I could have probably gotten my boat going at 17 knots or so... but generally, we'll sail at 9-11 knots instead. The ride is much more comfortable, the boat is under much less strain, and the risk of pitchpoling or capsizing is much, much lower.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
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