"Shortwave Sportfishing" wrote in message
...
On Mon, 27 Feb 2006 19:54:59 GMT, "Calif Bill"
wrote:


"Shortwave Sportfishing" wrote in message
. ..
On Mon, 27 Feb 2006 06:45:19 GMT, "Calif Bill"
wrote:


"Injam" wrote in message
hlink.net...
Why? If the propellers are turning at the same RPM and they have the
same
pitch, why would the 250 hp be faster?


"Harry Krause" wrote in message
. ..
Injam wrote:
Hello,

I'm trying to understand propellers.

If you have two identical boats, but the outboard horsepower
ratings
are different. One boat has a 200 hp and the other a 250 hp. Both
motors
have the same Gear Ratio. If the propellers are identical and the
RPM
of
the outboard is the same on each boat. Say 6000 RPM. Because of the
weight advantage will the 200-hp boat be faster than the 250 hp? I'm
thinking less weight less slippage otherwise they would be going the
same speed.

If the 200 hp engine is properly propped, the 250 hp engine will most
likely be underpropped with the same prop. The weight diff between a
200
hp and a 250 hp is not usually significant, certainly not enough t0
canel
out a 25% increase in hp.

Now, to your question...the 250 still might be faster, even if it is
underpropped.

It will be faster to the same speed. But, the 2 engines should not have
the
same pitch prop. The 250 hp will overspeed with the correct pitch for
the
200 hp. Same pitch and same RPM, other than a weight difference, both
boats
would be the same speed.

That's not the point. The point is that both run at 6000 RPM. Over
rev isn't an issue.

The issues as I understand them would point to horsepower being the
determination.

As long as you can turn that same prop at 6000 RPM the boat will move at
the
same speed. If I put your vette engine in my boat, at 3200 RPM I am still
at the same speed as my 330 mpi. It does not know that there is an extra
300 hp available.

Yeah, but yours is one of those goofy jet boats. :)

I understand what every body else is saying, I just don't agree.

Goofy jetboats? Try fishing this river in your pansy Ranger.
http://media.putfile.com/zigzag63