Prop Shaft Allignment

[Andrew Short]

Has anyone else experienced allignment problems? I have had my prop shaft alligned twice over the last year and while that removes some fairly serious vibrations imeadiatley after the service takes place the vibrations come back. I'm very comfortable that the shop carrying out the work is professional and knows what they are doing so i was wondering if anyone had had similar experiences with their 37.5.

 

[Steve Dion]

How about your motor mounts?

Andrew:Has anyone examined your motor mounts. Maybe these are weak and allowing too much vibration. I know that they are not cheap (about $100 each). It may be worth looking at. Also a 2 blade prop will tend to product more vibration than a 3 bladed.

 

[Andrew Short]

Prop Alignment

To Steve: thanks for your observation regarding the Motor mounts. What seems weird to me is that I experienced very smooth running for a period after the alignment was trued up and then over a period of time (probably 50 hours) it started to detriorate. The prop is two bladed but I also had that balanced at the same time so I'm kind of thinking something is actually shifting slowly. I'll check my mounts.

 

[Jeff Bacon]

Vibration

Andrew:I think I became an expert on vibration this summer.I had vibration that "had no cause". Everything was straight, in line, not nicked, cut, dented, folded, spindeled, or mutilated.Finally, someone suggested what, in retrospect, should have been obvious ( it wasn't to me, or the shop people who worked on my boat). 1. Check tightness of motor mounts. Every one of my mounts ( the part that attaches to the hull) was loose. Not finger loose, but I could put a turn or two on each one with a wrench. Also, the part of the mount that attaches to the rubber was somwhat loose. Again, not obvious, but turnable with a wrench.2. No personal experience with this, but was told the rubber mount itself will wear out, get hard, unflexible, etc. and may need to be replaced even though a visual inspection would revel nothing.Number 1 eliminated approx 80% of my vibration, which was serious.The mount suggestion came from someone on this list, I believe, and I would like to give credit, but cannot remember who it was....maybe Steve Dion ???Good luck !!! ..........Jeff

 

[Jerry Villines]

Try 4 Things

4 Motor Mounts, Yanmar suggests replacing them every 2 years. They are expensive but you can't live without them, kind of sounds like something else too. Deisel will deteriorate the mounts in no time. Look at the mounts to see that the pairs (front and back) have the same distance from the upper metal bracket and the lower plate. Shake the engine, you should have very little movement and should not hear metal hitting metal or fiberglass. I am assumming you have checked your running gear. Just a quick dip to grab the shaft and shake it (this ain't porno) will let you know if there is any movement will save a haul out. If your mechanic didn't think to check the mounts, look for a real mechanic.