Gould 0738 wrote:

:If your boat has been achieving the proper number of RPM at the two different
:elevations due solely to your past practice of swapping out the props, it might
:be "overpropped" at 4500 feet with the sea level unit. You will likely notice a
:decrease in speed, and a tendency for the engine to run slightly hotter.

Thanks for the response. I just found this prop calculator site
(http://www.rbbi.com/folders/prop/propcalc.htm) and put a few numbers
into it:

Engine RPM: 4800
Gear Ratio: 2.15
Prop Pitch: 15 or 17
Prop Slip: 15 (I've heard that is a good average to use)

The speed I get with a 15 pitch prop is 27, which is about what I get
with that prop at 4500' elevation.

If I put in 17 for the prop pitch value and leave all else the same, I
get 30.5 mph.

I'm not trying to be sarcastic here or question your knowledge, but
this seems to contradict your comment about a decrease in speed.
Comments? I'm just trying to understand.

Thanks,
Bob