Folding Prop Report

Sep 26, 2015
2
cs 36t toronto
hi Maine Sailor
you are a terrific resource and I thank you
I am new CS 36t owner and it has a 2 blade fixed prop
what diameter of j prop did you choose
Thanks
Ross
 
Dec 12, 2012
6
S2 9.2A Cranston
I am coming into this discussion 1.5 years later, and have to say it is very enlightening–unfortunately I did not read Mainesail's post before purchasing a 2-blade Flexofold myself over the winter (2016-17), and installing it about 2 weeks ago on my S2 9.2A (30' masthead sloop, cruiser). Talk about vibration. Soon after launching I realized I would be hauling her out again to fix or remove the new folding prop. I should say that FOF did not recommend the 3-blade for my boat, because the engine is fairly small I think (Yanmar 2GM), and it would've been to much "blade area".
I called Flexofold, and was connected with a technician in Denmark, who I must say was very patient and tried hard to help. But I have to say I was skeptical when he suggested that it was either an improper installation or a problem in the cutlass bearing (in the skeg), or a shaft that was slightly bent, or even engine placement being slightly off.
I did install the FOF mostly myself but had my boatyard owner check my work. I had followed the installation directions to the letter, and honestly it was not that hard. The vibrations do not happen consistently, there is less vibration relatively, around 2000 rpm than 1500. It gets particularly annoying at 2500-2600. The FOF technician said that if the prop were not balanced, the vibration would be consistent, increasing proportionate to speed.
So it does seem that the prop is balanced, and I fail to see how I may have screwed up the installation.
I have to say, Mainesail's skeg and shaft are much like mine, and that unfortunately, I'm afraid the increased distance between propellers and skeg, and the longer shaft (a few inches in fact) may also be causing "shaft whip" on my boat. I had no vibration (maybe a small amount at certain rpms) before, and nothing to suggest that the cutlass bearing was faulty.
Here's my dilemma: My marina operator has agreed to do a half haul, and has a good mechanic with prop experience who will come check the installation, the shaft, etc. But in all likelihood, I'm looking at vibration no matter what--and the increase in speed in lighter winds, which I was really looking forward to, just isn't worth the vibes--which are bad enough to cause other problems in the long run.
I really don't want to haul the boat only to launch her again and find the vibes still continuing. And I certainly don't want to think about other props (J-Prop sounds promising) not. So... I'm thinking it's best to put my fixed 2-blade back on, which frankly never caused problems, apart from being a little mouse-powered in current.
I doubt FOF would take back a prop that's been installed, used in the water, and painted with zinc paint, grey-colored.
I don't want this to ruin my sailing season, and am not ready to take a second risk by tweaking something, and having to haul out AGAIN! It seems going back to my 2-blad fixed is the wisest course for now.
If anyone reads this and has suggestions for or against, please let me know. THANKS
 
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