June 13, 2019 at 6:05 pm #225090
Hi All, I am tired of dragging my running gear around while sailing and am considering the beautifully expensive max-prop (or other feathering/folding) and looking for options/size recommendation for 424 with 1.5 inch shaft with 75 hp Yanmar and original V-drive. I know I can go through a process with PYI to get a recommendation but hoping some of you might have experience with Max Prop.
Many thanks. Ben
Papaya – 1979 Sloop, Hull #81, Woods Hole, MA
June 13, 2019 at 7:27 pm #225091
I replaced our fixed prop with a Seahawk Autostream from Jim Blanchard at H&H Prop in New England several years ago (800-325-0117). We have had no issues with it. Unlike MaxProp it can be rebuilt by owner should the internal parts need replacing.
June 13, 2019 at 9:28 pm #225092
We have a 19” 3-blade max prop on a 1.5” shaft and a Westerbeke 58 with the v-drive. We cruise at 6.5kts at 1800rpm.
I have not had to rebuild my max prop, but Rick raises a good point. Our max prop came with our boat (so not sure of its age) but we have been very happy with its performance for over 3 years and it is still in quite excellent shape. I have found max prop to be responsive to my questions via email. Attached is a photo of the prop before we splashed this year – the grey color is from an anti barnacle spray.
1983 424 Ketch “C” Layout
June 16, 2019 at 1:17 pm #225094
I researched this a few years ago, my notes are here.
Discussions with the propeller manufacturer indicated that the shaft-speed of the 75hp Yanmar is too high to properly mate a 3-blade propeller. The issue is tip-speed. At high tip speeds, the propeller will cavitate. I’d recommend that you have a similar conversation with your propeller supplier before you drop several boat-units on the wrong prop.
I ended up replacing the V-drive to gear down the shaft speed. This isn’t really a waste of money since these RV-20s are at the end of their lives anyway.
June 18, 2019 at 9:56 pm #225095
We replaced a fixed prop with a MaxProp on our previous cape Dory 36. You will find you lose about 5% efficiency in forward, due to the blades being flat rather than curved. On the other hand, efficiency in reverse will be much greated and there will probably be less prop walk, for the same reason.
For what it’s worth, we replaced the fixed prop on our 424 with a Gori and love it, but it is expensive. Mostly we wanted a folding rather than feathering prop because of all the crab pot lines here in the Chesapeake.
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