New to me boat, 1984 full keel
35k lb 43 footer. Powered by a Perkins
4-236 with a aqua drive and a fixed 3 blade
prop. The thing is butter smooth at any rpm
on flat water
but if it's choppy, every time the boat comes down a wave there's a slight vibration. Along with the vibration there's a slight audible noise
. To me it sounds like the prop is being over run as the boat accelerates due to its mass. I've watched at the stuffing box, and both ends of the aqua drive, you can see the vibration ever so slightly in the engine
, but it only lasts the duration of the down the wave, 3-5 seconds and then it's gone till the next one. Prop is tight, shaft is straight. Any thoughts, my first boat with a fixed prop maybe it's normal??