prop size

[pdellis]

Hello to everyone. I am the proud owner of a 2005 - 28TE with a Yanmar 6LPA-STP 315 hp. The boat is equiped with a Nibral 19x18 , four blade, left hand propeller. It also came with a spare prop. It is a Nibral 18x19. At 3600 rpm's I'm running around 19-20 knots. Will the 18x19 increase my speed enough to make a difference? Also, is running at 3600 rpm's harmful in the long run? WOT is 3950. Some people are telling me to run 80% of the engine's wot which puts me at 3200 rpm's +/-. I realize the main thing is to match the prop with the engine and it's not about speed but would appreciate some feedback about the props and rpm's. Thanks, Pat Ellis ( Wine Down - Venice Fl. )

[DougSea]

Hi Pat,

Some searches of the site should reveal plenty of information on your prop/engine combination.

As for the impact of the changes you could use the prop calculator on BoatDiesel (which is a great resource - but not free) and/or call a prop technician for some good info.

Hope that helps.