Overpropped 270 Sundancer?

[DieselDan73]

Hello, I am new here and I have a question. We just bought a 1995 Sea Ray 270 Sundancer. It has a 7.4 liter and Bravo 3 outdrive. It has a total of 537 hours, but repowered in 2009 with a brand new Gen VI engine. It has 155 hrs on it. My problem is WOT RPM. It only will go up to 3400. I know it should be 4400-4600. Top speed at 3400 is 34 mph. It has 24 pitch props and I looked at Sea Rays website and it says the boat came with a 22 pitch. The boat is bottom painted and usually runs full of fuel. I talked to a prop guy and he suggests that I go to 20 pitch props. He said this should get me close to recommended WOT rpm. I'm looking for other opinions since this will cost me almost $1100. Thanks in advance.

 

[rbh]

Re: Overpropped 270 Sundancer?

WE are running twin 260s on our 85 270.
We have had it to 43 MPH or 69.98 KMPH (@4650RPM+-) and are running 14x20 props.

 

[jestor68]

Re: Overpropped 270 Sundancer?

Have you run your numbers through the Mercury Marine prop selector?

It comes up with a 22.5 pitch set, assuming a 2.0 gear ratio.

But since you're only getting 3400 rpm with 24's, I'd go with 21's.

Doing the math(537 total less the 155 hrs on the new motor) indicates the previous owner managed to kill the motor in just 382 hrs lugging it like that.