Our Lehman 120 and powertrain feel very smooth up to around 1600 when a low
vibration appears.  This vibration increases up to WOT.  The vibration is
strong enough to make me feel uncomfortable at that speed.  I can't tell if
it is at engine speed or shaft speed.  The fact that everything is silky
smooth at lower speeds seems to indicate it is not an engine miss or balance
problem.  The prop is the original 3-blade.  The cutlass bearing had no play
when the boat was hauled 9 months ago.

Does anyone have experience with this phenomenon and have a fix?

Thanks,

Ed Pare'
M/V Scheherezade, CHB 34
Email: edbrooke@appleisp.net

around 1600 when a low
vibration appears.  This vibration increases up to WOT

Ed,
First of all go under the boat and see , feel , if any rope or whatever is
in the wheel. Good chance that is all . If not feel the prop for bent blades.
Even if it does not look nor feel bent it can very well be bent. That is
an easy and usually relatively cheap fix. If a twin screw boat then a shaft
and the wheel will be the culprit,  Been there many times!!!
CCC