"Gould 0738" wrote in message
...
Naw. You might only have to jump the engine speed to 2550 to get up on
plane...and your speed might go up 5-7 mph. Once on plane, every 100rpm
might increase your speed 2-2.5 mph until you hit 25mph.


Reasonable statement, but not consistent with the original example.

You're right. See my post with the corrected numbers above.
Here they are again:
3000rpm is 16mph and 6.5mpg.
3500rpm is 25mph and 6.2mpg