Originally Posted by topmast
Can you eliminate other possible causes? Things like engine
alignment, a whumpy shaft ,or bent at the cutlass, cutlass failing ,misaligned from birth, or lacking cooling
flow due to hidden growth, damaged blade pitch
.thust bearing in tranny not happy.?
Or, for that matter, a torsional vibration in the shaft, which will manifest itself as a high-pitched whine. On an exposed shaft the inevitable growth would unbalance the shaft just enough to damp it away after about a month, but if, as here, the shaft is mainly inside the boat
, you'd just have to put up with it—were that in fact the cause, of course.
But the obvious problems are that the aperture is too small in all directions and is blunt both fore and aft (about which defects you probably can't do anything significant); and the prop is too big and has an even number of blades (about which you probably can do something if your pockets are deep enough).
Or you could, as you seem happy enough to do, just put up with it and embrace it as part of your boat's personality.
Slightly off-topic—Topmast, no offence, but the bearing is properly called a Cutless, not cutlass—it's actually one of those product names (rather a clever one in this case) that has become generic, like "Hoover" meaning any vacuum cleaner, or "Thermos" meaning any vacuum flask. I guess a cutlass was a handy thing to have on a three-masted man-o'-war, but a naval sword could take a bit of explaining on a yacht!