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Foam-filled mast
Several years ago, at the first Atlantic City Sailboat Show I think, there
was a 'solution' to this problem. The Geougeon Brothers {the WEST System people - forgive the spelling} were manufacturing a 'large' catamaran {I don't know if they still are} at the time. Anyway, as I was walking about the hall I noticed what looked like a miniature 'blimp' {about 3-4 feet long} above the field of masts. It had their name on it and that's what I thought it was - an airborne advertisement. As I got closer, I saw that it was actually attached to the top of the mast of their catamaran . . . but still thought of it as an advert. I soon found out that it was really a piece of 'Safety Gear'. The shape was for aerodynamic reasons. A catamaran has 'Ultimate Stability' at TWO points .. . . completely upright AND completely upside down!! Having a sufficient quantity of extremely buoyant, and light weight, material at the end of a long attached moment arm reduces this to ONE. While you may experience a 'knock-down', you shouldn't be able to 'turtle'. OBVIOUSLY, it takes a great deal more material {or even air} then can be contained in the volume of the mast itself. Regards & Good Luck, Ron Magen Backyard Boatshop "Chris" wrote in message oups.com... An inversion may cause the mast to fill with water, and depending on the diameter and lenght of mast, the the leverage weight at or near the masthead would be significant. I think 1square foot of water is about 64 lbs. Or about 1 gallon of water is about 8lbs... Cubic foot. One square foot of water has a weight of zero. Anyone know what the leverage force would be needed to lift 64lbs at 30ft of leverage from the folcrum point? That may not be exactly the right question... Approx. 3000Nm, but that's irrelevant: Assume inversion. The mast will first be underwater. Then the water in the mast has neutral buoyancy. To get out of the inversion, the boat uses hull shape and keel weight, if not a racer designed to remain stable in an upside down position. But these have escape hatches on the bottom. Once the mast is parallel to the water surface, the keel has the best angle of attack to righten it. Much more than during strongly heeled sailing, i.e. a few gallons of water at the mast top won't do anything. Not even a few hundred pounds. If you want easier proof: You can hoist a person up the mast of even small keeboats witout inverting them. Chris |
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