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Bertram31.com General Bulletin Board
Re: B28 Props
Posted By: Bill Fuller In Response To: Re: B28 Props (jdail)
Date: Wednesday, 13 October 2004, at 9:32 p.m.
With 17 inch diameter props and 1 1/4 inch shafts, I would guess that you have the original struts. So you can not go any larger on either diameter of shaft size. With the fairly small shaft diameter and 1.5/1 gears I would go with the 3 blade props. Interestingly, my B28 was delivered from the factory with 17 x 16 props and 351 fords. The 17x16, 3 blade may be about right. A medium cup would also be good.
What sort of performance did you get on the way home? I would think that this set up would have given little more than 20 knots at WOT if you were pulling 2950 RPM.
Since this is a new boat to you, I would suggest that as soon as the motors are running correctly that you varify the RPMs the tachs read with a photo tach. With these motors, you will want to adjust the pitch and cup so as to reach about 100 (or more) RPM above rated. And then cruise them at or below the recommended continuous cruise RPM.
Talk to a good prop shop about all of this. Match the prop you have and HAVE BOTH OF THEM SCANNED. Matching the props is very important for optimum performance and economy.
And above all else, visit www.boatdiesel.com Tony Athens, the moderator of the Cummins and Yanmar forums, has a set of these motors in his brothers commercial boat with something like 15,000 hours on them.
Good luck with your new boat, you will love her.
And as you will see, there are many people on this and the boatdiesel.com site who will be happy to share their ideas.
Bill
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