24 ft offshore fishing boat setup questions

I have a 1973 24ft cuddy that was twin i/o volvo, very similar hull design to 233c formula from 1979 that i previosly had. I converted it to a single 1999 250 ox66 yamaha 2 stroke and a bracket Unsure of weight on boat guessing average weight of 24ft cuddy. Engine has a bracket setback of 30 inches. I took boat out first time and with 5 poeple in boat comes out of hole real quick and maxs out at 5500 rpm on limiter very quickly at around 38knts, cruise at 4200 is about 28kts. Not so worried about top end, would like a little faster cruise, but would like to make boat as fuel effeicint as practical, and do not want to damage my moter. the current prop was a freebie with engine 13x17 3 blade stainless prop no manufacture info was legible. thanks for any help.

Re: 24 ft offshore fishing boat setup questions

maxs out at 5500 rpm on limiter very quickly
Not so worried about top end, would like a little faster cruise, but would like to make boat as fuel effeicint as practical, and do not want to damage my moter.

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Ayuh,.... So prop it to run 100 rpms Under the rev-limiter, at wot...

Re: 24 ft offshore fishing boat setup questions

Hummm....let's check the prop size again. The 13 to 13 1/2" diameter props are made for the smaller (4.25") gearcases. You should be running props in the 13.75 to 15" diameter range.

Re: 24 ft offshore fishing boat setup questions

I checked prop again it has 17m stamped on it. and 13x17 written in marker on it. I measured from the center of the shaft to the the tip of blade and it measures 7 inches I guess it makes it 14inch prop? Not knowing what top rpms really are becuase the engine is limited would you recomend trying a 19 or going to 21 pitch? I need second prop anyways as spare but don't want to keep buying props till i get it right.

Re: 24 ft offshore fishing boat setup questions

OK, good. Seems whoever wrote on it was incorrect. Are you sure the limiter is at 5500?

Another question - on your test run was there water spraying up either side of the motor when you were cruising?

Re: 24 ft offshore fishing boat setup questions

No wasn't any water spray from the lower unit, ran about 30 miles in semi calm water and no apparent cavitation in any turn or bouncing over other wakes. other than concern over awesome hole-shot and quick run up to limiter boat performed perfect. No i'm not sure limiter is at 5500 except for fact that it got there so quickly.