RCE wrote:
"Dave Jones" wrote in message
...

I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load,
trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between
4200-4600?

Thanks
Davie


It should be optimized for your normal loading and usage and depends a lot
on the size of your boat. That RPM range indicates a likely I/O setup and I
assume it's a single engine. You may find out, as I did years ago, that you
will have two props ... one for normal use with 2 or 3 people aboard and a
second, lower pitched prop for when the whole gang shows up for a boat ride.

RCE

www.eisboch.com



Excellent advice. For my Evinrude 115(16' Glastron), I have a SS 19"
prop that is good for overall use, a SS 17" prop for heavy loads w/
watersports & gear for a day away from the dock, and a large surface
area AL 15" prop for power on demand (we sometimes pull 5 skiers with
this prop) but even with 5 skiers in tow, the engine will over-rev at
full throttle once they are up.

Our old inboard is getting tired, I have 2 14", a 15", a 10" & a 9"
NiBrAl (or brass) props for it, it likes the 14" cupped Michigan the
best at 4600-4800 rpm(engine is rated 220hp at 4400) . It over revs
with the 14" Stannus, to almost 5000 rpm, this we do only for short
bursts with a good load in the boat.

I/O & inboard engines(& most outboards - some Mercs are VERY sensitive
to this) really should not be run for any duration over recommended WOT max.

Target the middle of the range with your usual load.

Rob