Help Me Choose the Correct Prop Size

[Carbo]

First, a little backround: I've got a 2008 330DA Axius cruiser equipped with Mercruiser 8.1 twin engines(496 mag/375bhp)with cupped 24 props. I run on a lake at 1650 ft above sea level.
At WOT I get 44 mph but only 4500 rpms from each engine. I spoke with Mercruiser and they tell me while my speed is great I am toward the lower range of 4400-4900 rpm.

Their advice was to drop my props from 24 to 22 pitch, at which point I would get higher rpms and supposedly more speed and efficiency.

The boat runs great and I'm not looking to just spend a bunch of money, but I am curious as to what informed Sea Ray owners know about this topic.

Can anyone offer an educated response??

Much appreciated,

Peter

 

[Bridog]

Peter, I wouldn't bother. Looks like the 24's are correct. http://searay.com/Page.aspx/pageId/10531/Prop-Charts.aspx

 

[Carbo]

Thanks for forwarding the SeaRay chart. I'd like to think Sea Ray chose this particular size prop with a better understanding of how it works on their boat design vs the theoretical range of rpms that Merc publishes.

 

[KP49]

The elevation matters, especially in the summer when density altitude is up and horsepower is down. If I had a chance to TRY a set of 22s for free I'd do it, but I wouldnt spend the money to test it out unless you are unhappy with the boats overall performance.