Need help on prop selection

[blaster69]

I've got a 17.5' Aluminum boat with a 2003 90HP Merc. It currently has a 13x19 prop. I've just added a bow mount trolling motor and battery. My WOT RPMs have dropped from about 5300 to about 5200 at the trim level I like to ride at.

This is with two adults on board. So I'm concerned about WOT with 2 more adults.

The manual states a 5000-5500 RPM range, with preference in the higher end. Is it worth getting a 13 1/4x17 prop to get the RPMS up a little? I'm afraid a 17" prop is going to put me slightly over 5500 RPM.

If a 17" prop does put me over 5500 RPM at WOT with my load, will I be hurting the motor if I keep the throttle below 5500, or will I be doing the opposite of lugging at that point?

I'm assuming that if a 17" goes over 5500, I can trim down at WOT to safely drop it below/to 5500?

Thanks for any help...I have read the prop selection FAQ.

 

[Texasmark]

Re: Need help on prop selection

Relocation to the prop forum will probably provide you with better response.

Folks on here like you to run at the top of the recommended rpm range with normal load and max load shouldn't drop you out the bottom and not be a regular thing, otherwise max load should be your normal load and you need to prop for it.

HTH

Mark

 

[Texasmark]

Re: Need help on prop selection

Looks like you made it. Thanks administrator.

Now for some answers..............

Mark