CAM LEWIS
does the boat. It is as if you've sped up the conveyor belt. Before we leave yacht design, a few other points need to be men-
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tioned. First, why is an 86-foot catamaran, which is a displacement
boat, faster than an 86-foot monohull, which is also a displacement boat? A monohull with a lead keel, which resists the heeling forces of the wind tends to be as much as three times heavier than a multihull without one. Obviously, if you're racing horses, you don't carry an extra 25 pounds unless you have to. If you're racing boats, you don't carry an extra 55,000 pounds unless you have to. Lighter is invariably faster. Know too, that for every length a displacement boat travels it must push its weight of water out of the way. This is basically 2
‘Archimedes principle’. If for example, an 86-foot monohull weighs 75,000 pounds it pushes aside 75,000 pounds of water for each boat length it travels. In an around-the-world voyage of 26,000 nautical miles, that is 137,860,465,116 pounds of water, which is either my credit card number or 138 billion. A multihull, which weighs two-thirds less (Commodore Explorer weighed 21,280 pounds or 9.5 displacement or long tons) pushes aside twothirds less water, or a mere 46 billion pounds. Put that way, it's pretty easy to see which boat works less and, also, goes faster. Also, a catamaran with its wide beam—the newly dubbed and newly sized Commodore Explorer was 45 feet wide by 86 feet long—doesn't heel as much, at least initially. (Of course, that is until you cross the multihull Rubicon and it capsizes.) All that beam keeps the boat floating on its lines and faster than a boat like a 1 The opposite of a displacement boat is a planing boat. A planing boat is light enough that it can leave its stern wave behind and plane up its bow wave. In essence, it has escaped the hole. With much less of the boat in the water, it goes faster than a similar sized displacement boat. 2 Yacht designers show the relationship between waterline length and ultimate speed of a displacement boat, termed "hull speed," by the formula: Hull speed = 1.34 * square root of waterline length.
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