NYYC Race Week 2022 – 5 Minutes of Sailporn
So many great memories of sailing in Newport, Narrangansett Bay and paties at Harbor Court. Miss it bigly 🙁
Read MoreOn our way back from our LI Sound Cruise, the prop shaft started vibrating. It was fine below 17K RPM but above that the shaft vibrated quite violently.
The great thing about the sailing community is you only have to ask and you get great advice. I emailed a bunch of sailboat owners who know their onions and I got back some great advice. Here are two examples:
From Tim Fletcher:
The wonderful thing about the engine train is that there are so many things to vibrate!
Starting with the engine and working back:
1) Engine alignment - must be done in the water and is affected by the condition of the engine mounts (or feet - as Nigel Calder calls them). Yanmar reccommends replacing them every two years - but most can go up to 5, maybe 6 years depending on the condition of your engine compartment. Grease, diesel oil and general crud will soften the mounts (rubber) quicker. Lockwood once told me that if the mounts are compressed to less than an inch - it's time to change them. It is possible for you to check alignment yourself -- assuming the mounts are OK (i.e. newer and not compressed), you need a feeler gage, and the ability to back your shaft off slightly at the flange. Make sure to soak the bolts on the engine mount adjusters with penetrating oil (PB Blaster) for a good week or so before attempting. Also, your aft flange is keyed on the shaft and likely rusted (they rust quickly), and will be a real bear to get off. This is a great job for Doug or Lockwood depending on your level of masochistic tendencies - if you have any.
2) It could be engine vibration from the need for valve, fuel pump or injector adjustment. We had the valves and pump adjusted this summer and the engine runs much smoother.
3) Your shaft could be bent slightly. This will have to be checked on land and the shaft pulled. (I'm doing that this fall on La Neige).
4) Your cutlass bearing could be going bad. They typically last only 3 to 5 years (to lower side the more you motor obviously). If your bearing hasn't been changed in a few years and you motored a bit on your trip, it could be wearing to the point that you might start to notice it.
5) The shaft zinc might have loosened-up and slid down to the strut - or is just vibrating in place. I've never had this happen - but I guess it could in theory. You really have to tap them into place well when you mount them. Not sure why you wouldn't see vibration at all rpm's if this happened - but vibration is a funny thing.
6) Your prop could be malfunctioning - I think you have a folding or feathering if I remember correctly. If so, maybe the grease is gone or some dirt has worked into the gearing and preventing function. If your prop is fixed - did you hit anything with it that might have bent it or nicked it severly?
From Ron Canizares, I received this very detailed article.
A local marine diesel engineer suggested that I or someone else dive under the boat and check it out. I opted for the someone else option and had the mooring guy dive it.
Presto! He called me and it turned out I had a plastic bag wrapped around the prop. He cleared it and all's well now.
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