Hi all i have a 1998 Carver 530 with the Cummins 450HP engines that have both just been rebuilt... my question is what top speed and at what RPMs should i see... at the moment top speed is 20 knots... this is achieved with 3/4 full of fuel and a cleanish bottom hull... cheers
You can get the prop, torque, and fuel curves from the Cummins website for full info, but then translating that into speeds needs some testing. Those engines reach rated HP at a WOT of 2600 RPM. If you can reach, say, 2625-2650 with full load, resulting speed is probably tops of what you can get. If your current top speed of 20 kts is at 2625-2650, you're probably there. Otherwise, you maybe need some more hull cleaning, some prop tweaking... -Chris
They be just been rebuilt and the mechanic didn’t do a sea trial with you on board to make sure the engines reached rated RPM? They should be 2600 rpm engines.
A bit late to the party, but you should see about 24 with favorable fuel and conditions. I always found it takes a lot of tab to get the last few knots out of it. I would still think you should be faster than 20 with 3/4 fuel.