Speed Formula

[Ryan Patterson]

Is there a formula for engine x boat length x prop pitch = speed? I need to get an estimate of about how fast my boat will run, a formula would help. Thanks everyone for any help!

[Fish]

I don't know a formula but if you tell us what you got, chances are someone on here has already done a lot of the homework for ya.

fish

[Ryan Patterson]

Well its a crazy little boat I found! Its a 12' long 72" beam 3 seat Fiberglass boat and I have an 85 hp Merc to put on it. Just trying to guess how fast it'll run. I saw a smaller boat with a 70's model "hotrod" 65 or 70 hp johnson, it ran super fast! It was at an outboard drag boat race and the boat was called Old Yellar. Most of the drag boats couldn't keep up with it!!!!

[rdownes]

Naval Architect George Crouch developed a formula you could try:

http://continuouswave.com/cgi-bin/crouchcalc.pl