I am interested in the Idlewilde circimnavigation that used a 50hp Kuboda mentioned months ago in PUP, I am repowering and have been back and forth with Deere 4045NA and Kuboda v3300 and v3800 choices My boat is a round sterned, hard chined, bulbus bowed,1966 Sutton steel trawler, 43 ft of waterline, 13 ft beam, 4.5 draft,45,000 pounds when in the travelift slings. Since 1982 and 150,000 miles its been running a 3900cc 4 cylinder MAN originally rated at 90hp/3000rpm, detuned by the factory (injector pump and injector recalibration) to 44hp/1500rpm 150ft pounds of torque. This runs through a Borg Warner with a 3/1 reduction, 2 inch shaft turning a 34X26 3 blade nibril prop, This in turn at 1200rpm yields  propeller rpm of 400, 7.1 knots, 5.5 liles per gallon, it will rev out to 1500rpm does 7.5ish knots but the exhaust turns from clear to blacker when viewed at the exhaust water outlet. So I run 1200 rpm and I know that I am over proped at 1500 rpm, duh. 30,000ish

I am interested in the Idlewilde circimnavigation that used a 50hp Kuboda mentioned months ago in PUP, I am repowering and have been back and forth with Deere 4045NA and Kuboda v3300 and v3800 choices My boat is a round sterned, hard chined, bulbus bowed,1966 Sutton steel trawler, 43 ft of waterline, 13 ft beam, 4.5 draft,45,000 pounds when in the travelift slings. Since 1982 and 150,000 miles its been running a 3900cc 4 cylinder MAN originally rated at 90hp/3000rpm, detuned by the factory (injector pump and injector recalibration) to 44hp/1500rpm 150ft pounds of torque. This runs through a Borg Warner with a 3/1 reduction, 2 inch shaft turning a 34X26 3 blade nibril prop, This in turn at 1200rpm yields propeller rpm of 400, 7.1 knots, 5.5 liles per gallon, it will rev out to 1500rpm does 7.5ish knots but the exhaust turns from clear to blacker when viewed at the exhaust water outlet. So I run 1200 rpm and I know that I am over proped at 1500 rpm, duh. 30,000ish engine hours. The first 30,000miles on the boat were with a GM 453/140hp it would squat under full power, the round stern is not for planing-by design the boat "requires" 28hp to achieve hull speed at 1.1 not 1.34of the usual waterline calculation, As the Michigan Wheel Co. paper to the SAE in 1970 stated "the larger the propeller, the slower it turns, the more efficient it is", if you have the appature, and I do, it works. low quite operating RPM, long engine life, fuel economy, For the Kuboda I would like to achieve a shaft rpm of 450, and use a 3 blade 32X28 Nibril that I have as a spare-"fast prop". Looking at the v3300 and v3800 power curves I see a 1400-1800 sweet spot, 180ft/200ft pounds of torque 50ish hp (depending if I am using Koboda or Betas graphs), and reasonable fuel economy, So what I am trying to accomplish at a minimum is 400 shaft rpm which at 1600 and a 4/1 gearbox, 450 shaft revs at 1800 engine rpm.dare I hope for 500 shaft revs at 2000rpm? I am getting grief from John Deere (Bay Shore Marine Annapolis and have talked to distributors Flint and Bell) when I suggest that using my exsisting 3/1 BW and operating at 1200-1500 engine rpm would be inappropiate and not warrentable, but this is where the compareable fuel economy is. I think that Kuboda would prefer me operating their unit at beyond 1200 rpm, if the unit would be happy to push 45000 pounds with a 34/32 inch prop to achieve 400 shaft revolutions-I would be happy to retain a 3/1 reduction, but I think Kubodas HP numbers are to low-and thats why I have interest in the longer stroke 120 vs 110mm of the non turbo 3800 vs the 3300, I need the low end torque,I want the fuel economy of the lower revs,I appreciate the longer engine life, I don't need carbon buildup or ringsticking, Well thats my dilemma, Thats why I am interested in the Idlewilde Engine operating revs, reduction ratio and prop size --------------------------------- Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. --------------------------------- Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. --------------------------------- Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. --------------------------------- Ahhh...imagining that irresistible "new car" smell? Check out new cars at Yahoo! Autos. --------------------------------- Got a little couch potato? Check out fun summer activities for kids. --------------------------------- Ready for the edge of your seat? Check out tonight's top picks on Yahoo! TV. --------------------------------- Get the Yahoo! toolbar and be alerted to new email wherever you're surfing.