I have a 1990 straight bottom had stock 575 sci and Konrad 540s boat spun 30p 4 blade to 5200 for best of 79.6 and 28 5 blades at 5150 got 80.8 so something seems off with engines unless drives are super deep

If your having trouble spinning a 4 blade 28 more than 5k a five blade 28 won’t be the answer it will help your cruise but not top you need more rpm try a 5 blade 26p b1 prop that should get you decent cruise and a bit more top

where are the drives trimmed to when trying to get max speed, are you trimming them out as the boat comes on plane

Also something to think about is xrs on a straight bottom and bigger power might wasn’t to stay with a 4 blade I may have some 26p 4 blade off my old bullet you can try

mostly cruise anyway, top speed just for grins now and then. I am thinking 26 might be the answer.

sure let me know !

last time I went for top speed had the drives at “4” on the indicator

going to mark my indicators at neutral and above neutral for reference.

I’ll look this weekend when I’m at the shop working on the old girl

probably a conversation for other thread but quickly what’s the difference between hydros and bravos for these heavy flat bottoms?

A standard flat bottom seems to really like 4 blade b1 props my boat has been re rigged with a higher x so it likes 5 blade props a lot I haven’t had much luck with hydros on the cigs but seems some people do.