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I'm taking my props to get tuned up and was wondering what other diesel owners were running. IE 4 blade vs 3 blade, cupping, Engine HP, Engine type, cruise rpms and speed, top end rpm and speed. My 250 hp Perkins give me a 23 Knot cruise at 2350 and 26Knot top end at 2650 on three blade props. Thanks, Kurt

if you warm up the engines by putting them under a load for 5 minutes .then come back to dock and push thottle to limit in neutral for 30 seconds ,what is the the rpm at the wot. fuel injection thottle stop?

If you know what the WOT of your engines is supposed to be, and you're getting them with the props you have, you are properly propped. If you're running over, you need more pitch. If you don't make it, you need less pitch. Usually, 100 rpm's =1" pitch + or -. That's the basics, but you're usually best off discussing your situation with your prop shop. There can be things that your particular usage of the boat that can be addressed by the prop experts.

My 6BTA 250 hp Cummins with 1.5 gears and 21x22 three blades with no cup gives my B31 FBC about the same as you are getting with the Perkins...23-24 kts at 2400 rpm, 26-27 kts at 2650 WOT.

Don't overprop them. The enemy of good is better.

UV

I HAVE PERKINS RANGE 4 275 T I. AND TOP END IS 28.5 I HAVE 20/22 3/BLADE PROPS THE BOAT RUNS 22 KNOTS AT 22OO AND 24 KNOTS AT 2400 AND SO ON TO 2800.I HAVENT TRYED 4 BLADES. IS THIS THE SAME ENG AS YOURS I THINK SHAFT H P IS 250 THANKS KERRY

Cheetah, we have the same engines, props and output. The heat exchangers can be an issue with these engines. I'll PM you with more info. courtesy of Brewster Minton