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Old 11-30-2013, 02:25 PM   #14
Al
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City: ketchikan, Alaska
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler(extended to 30 feet) Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 2,206
BerettaRacer and Ronlord seemingly have come the closest to reflecting the goal.
As to measuring bell housings and such to retain the current reduction gears. It would not be worth the effort, most 454' or gas engines in general in these situations, as they will be below the required ratio for a small Perkins marine fitted engine as the examples given were. It would be thought that at the very least a 3:1 gear ratio required to swing the existing wheels on these gas pot applications.
As an example our boat (27 foot) has a 3:1 gear on a 58 hp Perkins with a 22X16 LH wheel driving it at hull speed of 6.5/7 knots at 2400 RPM. Assuming a boat in the 35-45 foot range with twin 58 hp Perkins, Yanmar, Volvo,Ford engines would achieve a similar result.
As to the ability of a planning hull underway for steerage. From actual usage of a 28 foot Christcraft l960's plywood planing hull where we did run the gas pot at 1500 RPM, enjoyed without any noticeable steering complications. In a following sea, ALL the boats owned by our family (Many!) experience the usual following sea habits.
At any rate, yes, the concept should be studied by as noted, "Backyard" boaters who have the time and inclination to undertake a project. Not being affluent as some, the concept was intended in part for "dreamers" of what could be when dollars are not available for the purchase of a similar finished first class model.
Thanks for the comments and response. Makes the Forum a hoot!!
Al
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