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Post by jeff on Feb 4, 2016 6:13:25 GMT
Found this, which gives insight into the way safety is able to be built in, as structural strength: Extreme Waves and Ship Design Craig B. Smith Dockside Consultants, Inc. Balboa, California, USA tinyurl.com/gqyppg8
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Post by jeff on Feb 5, 2016 19:44:05 GMT
Storm Resistant Boat Designing Based on the Geometry and Movement of Water Strider Ali Sheikhpour Ghasseminia, Ali Faraji
tinyurl.com/j9j2hor
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Post by Deleted on Feb 5, 2016 22:35:24 GMT
Storm Resistant Boat Designing Based on the Geometry and Movement of Water Strider Looks like they based their paper more on Vince Cate's work than the water strider bug. The bug sits 100% on top of the water. And they made an error in relating arm length to wave contact timing, because for any 2 feet in the water, there's a wave angle that will hit both simultaneously. Plus the normal acton of the boat is moving forwards, and those two legs will therefor most often hit waves together, and the rear pair will hit them together. On the surface of it, the multi-hinged and dynamicly controlled legs work nicely. But, the paper doesn't take into account side forces on the legs. Examining one front leg as an example, if the boat is moving forwards and encounters a wave that stops (or dramatically slows) forward motion of the foot, as it will, that lower leg segment is a tremendous lever for torquing the upper leg segment, and the force between segments is transmitted by the knee joint and held again by the joint connecting the upper segment to the main body. With tons of boat and 10ft long leg segments, these aren't trifling forces. Vince Cate didn't address these forces because (i suspect) he wasn't promoting his strider as a high speed foul weather rescue craft. Perhaps a look thru these links will suggest a better way to go: duckduckgo.com/?q=WAM-V+Proteus+Antrim
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Post by jeff on Feb 12, 2016 3:24:27 GMT
Rogue waves can, to some degree, be predicted. In and amongst, the first thing will be to look at the historical data. For any given location, there is a history of wave-heights. under the worst conditions expected, what were the typical wave heights? Take an average of that, and multiply by 2.3 and you get a rogue wave height. A rogue wave is the combining of 2 waves in a collision, resulting in some energy being expended upward, creating that extra height. With that number, comparing the mass of 2 waves, we get the mass of the rogue. That, in turn gives us the necessary information to strengthen a design, for the greenwater to be expected, resulting from the impact.
This greenwater is the mass of water going over the structure, which will have to be shed as rapidly as possible, but withstood, as well. Any floating structure is generally designed for a specific load and resulting buoyancy factor. IMHO, most losses at sea can be generally atributed to rogue waves and storms. If the structure cannot support the added mass, then it will be damaged. or even destroyed.
Rather than designing around the strength of materials, to make a lighter vessel, the design should be to withstand that additional, predictable load.
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