Nissan 20 hp on 14' Lowe Aluminum prop question

[cski]

Here is what I have:

2008 Nissan 20 hp long shaft on a 2008 14' X 67" Lowe Aluminum boat.

Current prop is stock aluminum 9.25 diameter with a 9 pitch, 3 blades

WOT is 6200 plus till I believe it hits the rev limiter. That is with an adult and 4 year old, fishing gear, and cooler on board. According to GPS, WOT gets us 24.6mph on plane.

I am concearned about hitting the rev limiter on the boat. I actually back down quite a bit to keep from doing so and it seems a waste to do so. My hole shot is pretty good and usually gets my on plane without to much of a problem. Any suggestions on a prop the would lower my WOT revs without messing up my holeshot. A 15 HP nissan I had on this boat could get this boat on plane, but the holeshot was horrible and I do not want to go back to that.

There seems to be a lot of science involved in changing the pitch of a prop and any help would be appreciated.

Thank you

 

[steelespike]

Re: Nissan 20 hp on 14' Lowe Aluminum prop question

The 9" prop is pretty far up the list it seems to me that with 1 1/2 aboard aboard
with gear, cooler and maybe an anchor Not likely to over rev.I think you should varify the tach is accurate.I don't know if the rev limit works oif the tach or not
but won't hurt to check it.If it checks out an increase of one size should work without losing too much hole shot and possibly increase speed a little.

 

[cski]

Re: Nissan 20 hp on 14' Lowe Aluminum prop question

The reason I believe its hittng the rev limiter is because at WOT, the motor sounds like it starts missing, my tach is 6300 plus. I back down to 6200 on the tach and it runs great without that sound/miss. I will try the 10" pitch to see if maybe I can use that last little bit of throttle, maybe get a little more speed. Any suggestions on a prop type, I boats has a solas amita 3 and 4 blade and rascal has a 3 blade. All are aluminum, the solas 3 blade is 50 dollars and the four blade is 59. The rascal is 73. Is one better than the others for my application since they are all about the same price. Thanks

 

[steelespike]

Re: Nissan 20 hp on 14' Lowe Aluminum prop question

From what I can tell the Solas Amita is a good prop in a 3 or a 4.While the 4 blade will usually improve hole shot,stay on plane with less throttle, improve handling on plane and at the dock and may reduce rpm and speed a little; based on your performance you probably don't need it.The Rascal should deliver close to ss performance.