150 OptiMax Prop ??

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TUMBLEWEED

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Hello all, I am currently running an 2004<br />150hp Optimax on my 1850 SportFish(Crestliner).<br />It has a 19 degree aluminum prop. I am getting<br />around mid 40mph with a 5200rpm wide open.<br />There is quite a bit of cavitation with this set-up when doing any turns. I end up having to<br />throttle back and reduce the turn. This is very<br />frustrating when one is trying to do any kind<br />of tubing. The Mercury site suggests a 21<br />degree set-up, but my dealer is saying it<br />doesn't work?? Another suggestion was that my<br />aluminum prop is flexing under load in the turns<br />and to go to a stainless prop. What are the<br />rest of the OptiMax people using?? My boat<br />is 18.5 feet and approx 2300 lbs. Is a 17<br />degree to small?? I would also think that<br />5200 rpms w.o.t is a little low as well since<br />the OptiMax is listed as 5250-5750 max rpms??
 

WillyBWright

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Re: 150 OptiMax Prop ??

You might try an Alpha 4-blade aluminum 18" if you boat in shallow waters. Otherwise stainless props with 4 or 5 blades can actually run with some of the prop out of water and stay connected to the water in more adverse conditions or tight cornering. I mention the Alpha prop because the gearcase suffers less if you hit bottom if you're using an aluminum or even a plastic prop.
 

ATF

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Re: 150 OptiMax Prop ??

Hey Tumble weed,<br />Sounds like we're in the same boat! Pardon the pun.<br />I've got a 2001 150hp opti on a 19.5 Fisher. Your setup is fairly close to mine. I'm 19.5 ft and about 2400lbs. I also get around 43mph GPS at around 5200rpm wot. <br />Mine came with a 21pitch aluminum prop and it was a dog. 4800rpm was about all I could do but with a little better top end speed.<br />I have played with a bunch of different 19p props with very little success. I too was told to try a 17P to see what happens. <br />I actually ended up buying a 19p tempest plus this year as I thought it performed pretty good last year when tested but after putting the new one on this year it isn't performing the same. <br />I tried a laser 2 and it is much better and gets those rpm's up to about 5400.<br />The only other option is to try raising the motor up one hole to see if there is any improvement. I still haven't done that yet as I want to try a few 17P props to see what it does for performance.<br />I won't be able to test anymoe props for about another 2 weeks but I can keep you posted if you like.
 

TUMBLEWEED

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Re: 150 OptiMax Prop ??

I am bringing it back in to the dealer<br />tomorrow morning. Will post back with any<br />input to the situation...
 

quantumleap

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Re: 150 OptiMax Prop ??

Is your motor mounted at the right height, and are you lowering the trim as you corner??<br />And you are right, you want it to run at the upper end of the RPM range at WOT. I would try a 17 pitch and see what that does. The dealer should swap it out for free as it should have been set up right to begin with. Good luck.
 

TUMBLEWEED

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Re: 150 OptiMax Prop ??

Good question about the height. There is room to<br />drop the motor down one notch?? The problem<br />in the corners is felt at a fully lowered<br />trim. In looking at some other OptiMax motored<br />boats, I haven't seen ANY 17 degree set-ups out <br />there. I had a closed throttle strike to the 19<br />degree prop I had, so I am going to get to the<br />bottom of the issue before replacing it with<br />another 19 degree aluminum again.
 

djhench

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Tumbleweed, I can relate. 2006 Crestliner Fishhawk 1850 with 150 Optimax. Motor is mounted in the center of 5 holes, thinking about dropping it down all the way. I too get cavitation when pulling tubers and can't trim out of it, have to slow down (Not giving crazy rides!). I have an aluminum Tempest Plus 19P and get 46 MPH top speed. Not sure I need to go any faster, but really want the annoying cavitation to stop. I did hear that my prop has vent holes in it and it can sound different? If I don't get answers from dealers, I plan to drop the motor and purchase a 4-blade aluminum 21 pitch prop. Two reasons, first to get more hole shot and with the 21 pitch bring some speed back and second for running the Mississippi and worry about stainless and rocks. If you get an answer, I'd love for you to post it! Anyone else with ideas, please let us know!
 

dingbat

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I haven't seen ANY 17 degree set-ups out <br />there. I had a closed throttle strike to the 19<br />degree prop I had, so I am going to get to the<br />bottom of the issue before replacing it with<br />another 19 degree aluminum again.
Degree?

Prop are measured by diameters and pitch.

14 (diameter) x 19 (pitch) no degrees
 

Chris1956

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Mar 25, 2004
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Stock Mercury props are not high performance. As such they do not hold the water well. A higher performance prop could solve your problem. Of course, that is predicated on the motor not being installed too high on the transom. At a solid cruise speed, is the antiventilation plate out of the water? If so, how high? If it is more than 1" or so above the water at speed, the motor may be mounted too high. If not, you likely have a prop issue.

Aluminum Turning Point Hustler props are pretty good, and inexpensive. For normal boats I like them in 3 blade. In your case, a 17P prop would likely be the correct one. If that doesn't fix the ventilation, consider lowering the motor on the transom.
 

GA_Boater

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Tumbleweed, I can relate. If you get an answer, I'd love for you to post it! Anyone else with ideas, please let us know!


Kinda doubt Tumbleweed will be answering your question. Maybe 14 years ago, but not today.

Closed.
 
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