harmonics vs vibration prop issue - SailNet Community

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Old 06-18-2008
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harmonics vs vibration prop issue

Have been going around and around re: replacing my three blade fixed prop with a 2 blade feathering max prop. Boat: Endeavour 32 with a new Volvo 30 (28hp). Yard found and repaired problems re: cutlass bearing, shaft, shaft dripless seal, and engine installation/alignment. Final decree: engine can rev to 3000 (rated 2800 to 3200) and achieve 6 knots in flat water. Vibration I feel is excessive above 2000 rpm is harmonics, not vibration and the engine in not moving on the mounts. Per manufacturer, I'll sea trial with the distributor and he'll show me that the feeling I'm getting may acceptable. I plan to race the boat so they both say stay with 2 blade, but I strongly think I'll ask to return and replace with their 3 blade. They say a 2 blade will always cause more harmonics/vibration and it should be acceptable in exchange for going faster under sail.

Please help!!!
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Old 06-18-2008
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A 3 blade prop is going to run smoother than a two blade.. no question. If you're really going for the Maxprop and want to spend the bucks I don't see a huge downside to going with a 3 blade (other than added cost) in terms of drag under sail.

It's going to be a huge improvement over dragging that 3 blade fixed, and you'll appreciate the reverse capability. The other advantage of the Max is you can, if necessary fine tune the pitch to optimize performance under power.
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Old 06-18-2008
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I'm colecting impressions of people of this forum asking them "what propeller you have". My previous boat had a folding 3 blade VOLVO and assure you it runs smooth and made a huge difference when sailing. I'm in the market again looking for a propeller for my next boat, and I feel overloaded with possibilities. If for any chance you test your Maxprop, please send me a note about your impressions; I appreciate your time ... Thanks !
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