Prop Question for my 90 Rude

[fishhawk16]

Well I'm getting closer to getting my boat dialed in just right, thanks to all the help I've got here. Raised the motor 1 1/2" with positive results.<br /><br />I have a 1997 Crestliner 16.5" with a 1996 Evinrude 90Hp. The boat weights about 900lbs the motor about 320lbs. <br /><br />When I fist go this boat it had a 14x21pitch prop on it she would run about 4600rpm at 46MPH @wot. I put on the spare 14x19pitch prop and now she runs about 5100rpm at 44mph with about the same weight. I belive this is still to low right?<br /><br />My question is what prop to move to, and what RPM at WOT would be best for this boat/motor combo. If I moved to a 17 or 15 pitch prop what could I expect in terms of RPM and MPH?<br /><br />My applicatons are just about everything you can do with a boat <br /><br />Thanks in advance for all the great advise.

 

[DJ]

Re: Prop Question for my 90 Rude

You can use the general rule that one inch in pitch is equal to about 200 rpm's.<br /><br />The 13 1/4" X 17" is probably your best bet.

 

[youngboater]

Re: Prop Question for my 90 Rude

I have the same setup but with a 75 HP on a 16.5 Lund I use a 19inch prop (aluminum) 13inch (I think) if that helps. I am dead center in the middle of my recommended RPMs too. I hope this helps a little bit.

 

[fishhawk16]

Re: Prop Question for my 90 Rude

Youngboater,<br />What speed do you get on your lund? <br /><br />DJ <br />That would work out to about 5300RPM is that OK for that motor? Can I expect a speed increase or should it be about the same?

 

[youngboater]

Re: Prop Question for my 90 Rude

With my boat loaded with 27Gal of gas 2 people a 305lb motor and fishing gear I'm just under 2,000 pounds. I only get about 35MPH because the boat weighs so much. It is very very stable though when I get in some big waves so I don't mind the weight of the boat. I think your speed is great for your setup.

 

[jim dozier]

Re: Prop Question for my 90 Rude

Fishawk dropping down to a 17" pitch as recommended by DJ above probably won't change your speed but will help your engine live longer. Based upon your rpm with the 19" you'll be right at the max recommended rpm at WOT which is where you want it. Then when you put 2 of your buddies and a cooler of beer and some gear in there your engine won't be running at a painfull 4000 rpm anymore.

 

[fishhawk16]

Re: Prop Question for my 90 Rude

jimd<br />so 5500rpm is max for my engine thanks<br /><br />youngboater<br />I agree with what you are saying with respect to he ride quality. Lunds make a very good hull with quality components. They are built to last and can take the pounding. I feel the same way about my Crestliner, every time I go over some big waves.