2700 SCR Prop Size?

[bmetro]

I have a 2002 2700SCR with the 6.2 MPI motor(Bravo III).
I was wondering what the correct props are for this setup.
I currently cruise at 4200 rpm (very high) and 25 mph (very slow). I think my tach gauge may be off, but not sure. I would just like to get a basic idea of the props I should have.

Thanks,
Happy Memorial Day!!!

[seapuppy]

you should be running 22-24" pitched props....I ran 22's and always thought that was too high cuz I'd cruise at 4000 rpm at 30mph.....I wanted to drop id down to 3600-3800rpm with 24's..never could find anyone to trade with me...

now if your turnning 22-24" props..and running under 30..then you may be overloaded....might think of either checking the tach connections or putting your boat on a diet....


SP

[shrew]

I was always under the impression that you gauge prop pitch based on max rpm @ WOT. If the RPM's @ WOT are higher than the max rpm rating of the engine you're under propped. If the RPM's @ WOT are under the max rpm rating of the engine your over propped.

I understand that you would need to factor in the weight of people and gear, so the props would be better suited to be sized based on the typical load the boat would theoretically carry. Otherwise, you could increase prop pitch in an attempt to decrease average rpm's at cruise speed, but be overloading the engine when trying to run at lower rpm's or when trying to out of the hole to get up on plane.

Am I just way off on this one?

[seapuppy]

Shrew...that usually stands true when measuring the prop/performance of a boat...but the 6.2ltr engine redlines at 5280 rpm...Mercruiser says it's ok to run it tighter than a normally asperated engine...as a matter of fact..the factory guys told me they wanted my 6.2ltr mpi engine under load to run a bit tighter...around 4k - 4200 while at cruise...I always slowed it down to 3800 rpm and ran at about 26-28mph....so....your right in a sense for a 5.7ltr carbed engine..but not the 6.2ltr mpi....totally different rules...

SP