Vibration under power

[Ivan Edwards]

I would like to solve a vibration problem when under power at greater than 2500 RPM.Seems to come and go with the swaying of the boat from side to side... Had alignment, shaft checked for straightness,new cutlass bearing, prop cleaned...I'm guessing that there is enough softness in the engine monts that the engine is swaying and causing mis-aignment. Do I replace the motor mounts?Should I try one of these break-away isolators,or a CV joint, between the prop shaft and the transmission?Have the prop/shaft re-balanced/straightened?Other ideas?Ivan Edwards

 

[larry w.]

vibration

Ivan; You may be coming up against the limit of water adhesion and experiencing cavitation and might need some adjustment on your prop pitch. What speed does 2500 RPM give you and with what engine?

 

[Ivan Edwards]

6 knots

Its a Volvo 2002, 2 cyl Diesel (18 hp), 2 blade prop, pushes the sailboat up to about 6 knots at 2500.

 

[Paul Goodman]

vibration checks

Check the motor mounts particularly where attached to the boat. Mine loosened over time (on 1991 Beneteau Moorings 38). And check the gear on the engine (alternators, compressors, hoses, etc) to ensure it doesn't touch any of the walls around it. This can induce a vibration into the whole boat structure that sounds awful.