posted 09-09-2002 07:58 PM ET (US)

Here is the process for deducing the proper pitch propeller:1. Determine the total boat weight

2. Determine the target optimum speed using the speed prediction forumula given in the REFERENCE section.

3. Use the propeller calculator to determine the propeller pitch needed.

EXAMPLE:

Let's say your total boat weight is 2400#.

With 175 Horsepower, the speed prediction forumula indicated you should be able to hit 48 MPH. (Using 180 for the hull constant.)

Now determine the lower unit gear ratio and the maximum engine speed, let's say 2.0 and 5500 respectively. Use thepropeller calculator to determine the pitch needed.

Enter 5500 RPM, 2.0 Gear ratio, Slip = 8%, Speed = 48.