Re: Strange noises from below...
After our last haul out for anti fouling in November our girl developed an odd thump thump when in reverse. This with a Flex-o-Fold prop. She was again hauled late March for another reason and while she was out I gave the prop a really good going over to make certain it opened all the way out and had no obstructions. Since going back into the water the noise/vibration has stopped. I am told it could have been cavitation caused by the prop not fully opening (possible something caught up inside) and went away after I had cleaned away the obstruction.
Soooo .... if you have a folding prop maybe same problem. If fixed prop simply ignore everything I have just said.
“Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life.” Terry Pratchett