Reproping for 4-5 hundred rpms

[Pursuit2550]

I have a 91 25' Pursuit w/02 Yamaha 250 ox66. I am currently running a m19 prop, which is 151/4 x19. My engine is at a perfect height, I am running at about 5-5100 rpms. I would like to get as close as possible to 5500. I was wonder what would happen if I put on a sws 2 prop of the same diameter. Also what would happen if I put a 14x19 prop, I believe its a sws 1. I can get the 2 mentioned props for good prices and it always a good idea to have a spare onboard.

Thanks

 

[Pursuit2550]

Re: Reproping for 4-5 hundred rpms

Ok, scratch that sws 2 out. I just spoke to the owner and it turns out it the same prop I have. It stamped m19 and doesn't say sws 2 on it.

 

[craze1cars]

Re: Reproping for 4-5 hundred rpms

I think very little would change if you got the same pitch in a smaller diameter.

For 400 to 500 rpm gain, you'd do better to get a 17 pitch prop to replace your current 19.

 

[Pursuit2550]

Re: Reproping for 4-5 hundred rpms

I just talked to a prop shop. They told me that since I am at 5-5100 rpms, that I should just leave it at that. They told me that if I go up in rpms that I will lose speed. I am currently running 42-43 mph. I wanted to try to be closer to my max rpms and pick up some mph.

 

[craze1cars]

Re: Reproping for 4-5 hundred rpms

Very possible they are correct you would lose a little speed. I don't think it would be much. You would also gain substantial holeshot. All depends on your goals, which you did not share...and also depends on what type of prop you're running now and what you are considering purchasing...which you also did not share.

I believe it may be entirely possible to gain RPM, gain holeshot, AND gain a touch of top speed all at the same time...ESPECIALLY if you're currently running an aluminum and are willing to try a stainless...

And I may also be wrong...

 

[steelespike]

Re: Reproping for 4-5 hundred rpms

When you say the motor is at the perfect height do you mean a certain demension or at a height with just a touch of ventilation in extreme manuvers?Usually if you have no venting at all you
may be too low.While this is a little speculation it is possible that the increased rpm could get a little more boat out of the water increasing rpm and speed.
It would be very good if you gave us your present speed at max rpm.

 

[Pursuit2550]

Re: Reproping for 4-5 hundred rpms

Right now hole shot is not the best. You also have to consider its a 25' Pursuit with a single 250, I don't expect it to jump out on plane. I am running a Yamaha SS m19 prop. By right height I mean navigation plate is just above the water and yes I do cavitate on maneuvers. My cruise is at 32-34 mph at 4-4200. I max out at 5-5100 at 43-44 mph. If possible it would be nice to improve in all the areas, holeshot, rpms, and mph.

 

[Pursuit2550]

Re: Reproping for 4-5 hundred rpms

Anyone have any ideas?

 

[craze1cars]

Re: Reproping for 4-5 hundred rpms

Same as I recommended earlier. I suggest a 17 pitch. And stay with stainless. Choose an aggressive design with cupping & rake, which all helps with stern lift. As always I offer no guarantees, but I THINK you'd see a variety of benefits across the board....ESPECIALLY in planing out faster.

IMO a test drive from a local prop shop or marina beats mail-order gambling any day....