[Eric]

Sorry about that.

Port SN: 46647462
Starboard SN: 46652475

[Eric]

Rob,

Thanks for the thoughts. My instincts also are to have the props checked again. The shop that did the overhaul has a very good reputation and is highly regarded locally and has said they are happy to recheck their work. It’s obviously problematic to pull props with the boat in the water on a lake with limited ability to haul.

With that said, I don’t think it’s the “singing” issue with the starboard engine. I am aware of and have heard that phenomenon first hand, and this is not that. It’s a very sharp piercing physical low amplitude high frequency vibration that adds a deep harmonic rumble to the background noise of the boat and can be felt through the entire hull. It almost seems like the engine is hard mounted directly to the stringers and you feel it directly as if there were no soft mount at all.

[Eric]

I hired another service guy to come check alignment who knows what he is doing. He found one motor 15 thousandths out, which is 5 times the allowable limit of 3 thousandths. He was able to get all measurements below 3 thousandths, and it definitely made an improvement.

I was not able to sea-trial the boat with the mechanic, however on the next run I noticed the boat still has significant vibrations. I did some more playing around and found that if I put the port motor in gear, its totally smooth until about 1600 RPMs, and then a very pronounced wobbling like vibration develops that shakes the whole boat. You can visibly see the bow-rails shake back and forth.

If I do the same exercise with only the Starboard motor in gear, from about 750-1100 RPMs I experience a very sharp piercing type high frequency vibration that eventually goes away above about 1100 RPMs and I feel no evidence of the wobbly vibration that I get on the other motor. However, the sharp vibration manifests in a very uncomfortable ride at low RPM and adds significant perceived noise to the boat’s occupants.

With both engines synced under normal use, I get both the high frequency effect at low RPMs from the starboard motor as well as the wobbly shaking at higher RPMs from the port motor. Its very frustrating.

I know these are very difficult issues to deduce and diagnose over the internet, but any tips you all may have would be vert appreciated.

Remember, all 8 engine mounts are brand new, and both props were repitched and reconditioned including dynamic balancing over the winter. They were re-installed professionally and properly lapped to the shafts.

Thanks
Eric

[Author]

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