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Re: Eeek! Catamaran thoughts

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  • c.ruzer
    Tom, Sitka Explorer [LWL 37 1 ; LWb 7 2; LB 5.1; Midsection draft 8 ; Disp lt ship 5500lbs; Max displ 7400lbs; Inboard Deutz 2cyl deisel 30hp @ 3000rpm
    Message 1 of 3 , Mar 3, 2011
      Tom, Sitka Explorer [LWL 37'1"; LWb 7'2; LB 5.1; Midsection draft 8"; Disp lt ship 5500lbs; Max displ 7400lbs; Inboard Deutz 2cyl deisel 30hp @ 3000rpm (air/oil cooled - "no freshwater pump, no saltwater pump, no strainers, impellers, heat exchangers, hoses, clamps, to buy, insall, see corrode and age rapidly in salt air."), or 50hp 4T large prop outboard; 220gals fuel; Range @ 5mpg 1100nm, @10mpg 2200 at most efficient speed] developed on the Topaz model has this bottom type, slightly truncated at the stern, for high "rule-bending" semi-displacement speeds. Target speed is not hull speed of 8kts, but SL 1.7, ie 10kts and better!

      It's said by PB&F that "The advantages of these shapes is clear though mostly overlooked by the mainstream. There is ultra simple construction with mostly straight cuts, frequently at 90 degrees, for rapid framing and joinerwork, the option of acheiving massively strong bottom and topsides structures by just stacking the ply, super efficient running ie., low-hp requirements for the bang, maximum stability per given beam, maximum useful interior floor space, and more."

      The Sitka and Topaz have a filleted vee bottom at the bow, but your stretched Eeek hull may not require this treatment as less blunt than a Slicer design at the bow. Your Eeek catamaran hull (LOA 36, LWB ~31', LWB 3') has LB ~10, so is right at the bottom of the slenderness range for high sail-powered displacement catamaran speeds. Sail-powered planing (& semi-planing?) catamaran hulls are terrible performers, but you have engine power with a "rule-bending" bottom! Eeek power cat hulls twice as slender as that of Sitka might "bend" the rules more, or even "break" right through them! At BOA 14' the hull spacing may be just far enough apart to avoid interference.

      --- In bolger@yahoogroups.com, "tdsoren" <tdsoren@...> wrote:
      > All this discussion of Eeek has reminded me of a design I was thinking about for a good shallow draft catamaran for the Columbia river here in Oregon. I currently live on a 36' Grand Banks trawler that requires 4.5' of water minimum, and there have been MANY times I've wished for shallow draft as well the ability to sail/motorsail. Not to mention getting away from 12 injectros, 2 injector pumps, 2 raw water pumps, 6 heat exchangers.....
      > The most efficient/fast motorized cats on minimum power have Displacement hulls. If they're kept fine enough, you can do @ 3 times the normal hull speed with much less power than attempting to plane. The stern design in the Eek is very remiscent of the better displacemnt power catamarans. All of the heeling issues under sail essentially go away. 12"-18" of draft with any appendages up. Hmmm......
      > A couple of 32-36ft long, 30-36" beam Eek hulls with enough bridgedeck to house a simple cabin and a double berth as well as give a 14' beam to fit in a normal slip. Hmmmmm......
      > really fine entry front and back for the follwing wakes from the 60' diesel mansions as well as the wind against current chop. Maybe narro enough the the exposed flat forefoot doesn't slap or pound TOO badly. Hmmm....
      > Tom Sorensen.
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