props

spincycle · Post by **spincycle** » Tue Mar 18, 2008 11:39 am

Can any one help. I have a 1988 12 meter with 671 450 hp. I believe i should be able to cruise at 24 knots, but i am lucky to get 22. I have 24x27 wheels. They are not cupped but i was told they should have a super cup. Does any one have any suggestions.

Stripermann2 · Post by **Stripermann2** » Tue Mar 18, 2008 1:00 pm

Yep, Jav, a forum member is pretty good with figuring those formulas.

As mentioned, your hull must be clean and all other mechanicals in good shape, performance wise.

Cruise speed and WOT speeds are two different speeds. If say a boat can go 30Kts WOT, then it's cruise speed may be around 24kts...

What are your rated WOT specs and cruise specs for the boat and for those specs, what are the listed RPMs?

tgcasey · Post by **tgcasey** » Tue Mar 18, 2008 1:54 pm

I have the same boat but with J & T 671 485HP.

Before I purchased the boat on the sea trial the boat would not go over 2375 - 2400 RPM. I did some investigation and found that the boat should have 24 x 26 props, I also found from doing some research that many people have to tweak the props to get to the appropriate RPMs. I had an inch of pitch taken out and the RPMs are where they need to be, I have not confirmed speed.

Tom

rossjo · Post by **rossjo** » Thu Mar 20, 2008 11:13 am

Weight?