My Bristol 31.1 with the Universal 24hp does 6 kts at 2000 rpm, and won't rev past 2500. Clearly it's a bit overpropped based on max rpm. But boat performance is excellent. I was motoring into chop last weekend, and it only slowed down to 5.5.
This is by way of saying that a coarser prop might not extract maximum hp from the engine, but it might result in better performance for you.
I heard that Bristol offered a 2 blade
, and 3 blade
prop as options.
The 35.5 is only listed with the Universal 24hp - so it sounds like someone did an engine swap to a Yanmar on yours? Strange choice, I'd have put in a Beta and re-used the engine mounts.
Sounds like they also swapped the prop because you wouldn't be doing 3500 rpm with the original 3 blade.
Suggestion : find out what it is, go one step coarser. At this stage I suspect your prop aperture will accomodate a considerably larger OD and/or pitch than you have, because I suspect what you have is pretty small, and that aperture was sized for a big, coarse, prop.