Mainship 390 Volvo Diesels

[DrSurfFisher]

I have a 1997 Mainship 390 with twin TAMD 41 Volvo diesels that is overpropped. Can someone tell me the correct diameter and pitch for this boat and engines?

[RT Firefly]

Greetings,
Welcome aboard.

[gaston]

Sorry I'm not been a smart ass but who told you that you were over propped ?
Did that person suggest what size was needed or why its over propped .


Its just that I went through the same thing some years ago and turned out my original prop did a better job than others that were """expertly""" suggested and lots of $$$ spent

[jwilsail]

Could be they did a sea trial and they were not able to get to max rpm at WOT so they assume the props are over pitched. I am no expert but I think that a prop shot can adjust the pitch.

Note the word assume, there could also be mechanical issues keeping the boat from reaching its potential. Could be as simple as restricted fuel flow are something much more expensive. An oil sample would be a good start.

[bayview]

simple direct answer is go to a good prop shop because there is no standard prop for all set ups.
For any reasonable response you will need to post more info on what's happening.

[Marlinmike]

I agree with bayview, take accurate RPM readings (strobe) and with props in hand bring them into a good prop shop, they can measure and discuss options with you.

Originally Posted by bayview

simple direct answer is go to a good prop shop because there is no standard prop for all set ups.
For any reasonable response you will need to post more info on what's happening.