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From: Tom O'Meara (no email)
Date: Wed Jul 04 2001 - 11:03:06 EDT
At 03:34 PM 7/3/01 -0400, Bob wrote:
>Apropos monohulls, catamarans and trimarans: -
>
>A properly designed monohull has inherent stability;
Correct. It is ultimately stable sitting on the bottom in however many
fathoms it happens to sink in.
>Even if completely rolled over, it will right itself, as long as it does
>not fill with water.
Ah, just a SMALL caveat, eh?
> Sailing with the rail in the water may not feel very
>safe, but it is.
Correct. As long as you like sailing on your ear, have at it.
>Multihulls are completely different.
Correct again.
>They do not heel and spill the wind
>from the sails. Once the moment of the wind force exceeds a certain
>limit, they will capsize, and cannot be righted again at sea by any normal
>means.
You only get "partially correct" on this one. The "once the moment of the
wind" line is balderdash. Properly sailed cruising multihulls can
withstand any wind that a properly sailed cruising monohull can withstand.
>This is aggravated by the design of most cruising cats, which have a
>bridge deck fully covering the space between the hulls. When the weather
>hull lifts,
Balderdash. The weather hull on a properly sailed cruising cat NEVER
lifts. Sorry. For a long time, a multi designer offered a $10,000.00
purse for anyone that could bring him a picture of a cruising catamaran
flying a hull. He never lost his money.
>In addition, if this deck is low to the
>water, there will be pounding in heavy seas.
Correct. Some of the older designs had insufficient underdeck clearance
and would pound. Not the newer boats from creditable designers or even the
older designs that were done right.
> For this reason, the deck
>needs to be raised fairly high, but this compromises stability even
>further, and increases the capsizing moment of the wind.
> Much of the
>weight of stores is stowed high above the water, which makes them even
>more unstable.
Here you have departed reality. Sorry, but you are WAY out on another
planet with design comments like these...
>Racing trimarans, which are designed for heavy weather,
Man, where are you getting this stuff? Almost the ONLY multis subject to
capsize are the *racing* cats and tris, not the cruising boats. Racers are
pushed way beyond safe limits by a crew taking known risks in attempting to
win races.
>The pontoons have limited buoyancy due to low displacement,
>and this further enhances safety. When the force of the wind increases to
>a certain point, the lee hull will be driven under, which greatly
>amplifies drag, while the weather hull lifts clear of the water and exerts
>no drag at all. This creates a strong lee helm, so the boat turns sharply
>away from the wind, instantly reducing the heeling moment and usually
>preventing a capsize.
Wow, wrong again. I don't know where you are getting this stuff, but
passing it off as useful information is disingenuous at best.
>The great advantage of mutihulls is speed.
Wrong again. Although most cruising multis are faster that an equal length
cruising mono, they are not THAT much faster. The advantages of a multi
are many:
Level sailing... no more pots and pans slamming to the deck in the galley.
Unsinkable if properly designed.
More spacious for a given length.
Disadvantages are that if you load one up beyond its designed payload, they
lose whatever speed advantage they had. If you are marina hoppers, you
have to plan ahead to get space. (However, at present we are not finding
that to be a problem even in the Great Lakes, which seldom sees ocean going
24 ft. wide multis.)
That is it.
>While it is often
>possible to survive for a while in a capsized multihull, that is not on my
>list of scenarios I want to experience.
Sinking to the bottom of the sea and trying to save oneself in a little
rubber raft are not on the list of scenarios I want to experience either.
Chris White already collected the data on multi safety and guess what...
they are MORE safe than monos for offshore cruising. He documents the
capsizes that occurred, and their causes, and also compares the
survivability issues in both monos and multis. Give him a read.
We are currently sailing a boat design that has been credited with more
successful circumnavigations than any other multi. Almost ALL were owner
(amateur) built which shows a robust design able to take care of its crews
usual lack of experience.
Todays ocean going cruising cats and tris are safe, fast and stable.
This has been hashed out before. If you don't like multis, fine... just do
not continue to propagate debunked information as gospel.
Fair Winds,
Tom
Tom & Jackie O'Meara
Searunner 40 Trimaran, "Sea Skate"
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