new motor - how and what prop sizes to test?

[txhorns0508]

I'm getting a 250 hp yamaha put on my 1988 mako 231 right now. What propeller sizes do I need to test out to pick the right one? Do I basically just see which propeller makes me go the fastest at 4000 rpm (my cruising rpm), or are there other things I need to look for? Thanks.

 

[steelespike]

Re: new motor - how and what prop sizes to test?

You need to test for the best wot rpm and gps speed.The motor needs to be able to rev freely within its rpm range.
Once propped correctly you can run at what ever speed you like.
You need to play with the cruising speed it can be from just on plane to about 1000 rpm higher.
About the only way to be sure it is the best cruising speed for economy is with a flow meter.