New prop. On the way.

[trout74]

I've posted about my RPM issues. Dealer said I had a bad tach. He replaced and I took boat out and still have RPM's of 4750 max on my 2014 mercury optimax 150pro xs. Boat is 24 ft. manitou tritoon with VP HULL. This last weekend I had 3 adults and 4 kids on boat with full gear and coolers and GPS top speed was 31.9 MPH. But that was at 4700 RPM's. Prop is a 15 pitch mirage plus. Mercury and manitou both said that the motor should turn that prop and the mirage was good for that setup. Dealer has agreed to get me a 13 pitch mirage plus and swap it out no charge. If my RPM's go up to say 5300-5500 will I loose or gain speed? Dealer thinks I won't gain any speed and kinda hints that I should stay with the 15. I asked mercury about an emerita prop and he said the mirage was better for my setup. What do you guys think? I really wish it would turn the 15p at 5500-5700 rpm's as it rated for but it just doesn't on my setup.

 

[craigmack]

I'm running a 15P Enertia and get 5300 with 2 people and gear, GPS reads 36 MPH, The Enertia is a fantastic prop though it will cost you some $$$.

 

[BrianMc]

Sounds bow heavy to me. You could be running too flat for the strakes to finish lifting.

How much of the people and gear are on the front? Try moving weight to the back,then run with as much trim as she'll take. If your speed increases go with the enertia. If it doesn't stay with the mirage. The mirage is a good stern lifter for a 3 blade. The enertia is a better bowlifter,also with enough bite for a big toon.

The enertia is 3-4 mph faster than my stern lifting prop on my 25',and my bow is light.

 

[lakegeorge]

You are almost 1,000 rpm's under what the motor is rated for, so yes, they should do something about it. Have them try different motor heights along with different props.
I never did like the way my 150 merc 4 stroke performed and I won't buy another one. I can't get over 5,200 rpm's, motor is rated for 5,800.
Keep us posted.

 

[Dan JC 23]

Like the statement above, it might be in the setup, and the height of where the motor is mounted. I run the enertia prop on a 150 Merc four stroke, and always achieve maximum rpm at WOT on a 23' tri. Only drawback is there is no bite in reverse when needed.

 

[trout74]

So you guys think it would be better to try a 15 pitch enertia over a 13p mirage plus?

 

[craigmack]

I think ultimately it'll be the best prop but you seem to have one or more other issues that need to get resolved first. Has the linkage been checked to make sure you're getting the full travel of the throttle?

 

[lakegeorge]

I agree with craigmack, you have other issues besides the prop. Your running 1,000 rpm's under what the motor is rated for, don't let the dealer or anyone else tell you that that's correct,it's not.
Have they tried different motor heights? It's hard on the motor if it's not getting near full rpm's.
Have you looked at the Mercury web site to see what kind of tests they have done with your engine? there's a lot of good data there.

 

[craigmack]

Have you checked the toons for water? The bilge pump in my center toon recently died and I had 100 gallons of water. At 8.34 lbs/gl that's an extra 4 adult males. As to why I had so much water I can only guess the pump died soon after I launched the boat in May (it stays in the water) and I have a small leak.

 

[trout74]

Thank you very kindly for all the remarks I've taken what you have said and decided to order the 15 P inertia prop. As for motor height I called Manitu the boat manufacturer and they said I needed to have the motor mounted in the lowest spot the center tube is quite a bit bigger than the side tubes and that's where they said they wanted it. Not saying I couldn't lift it but sort of think I should leave it where they told me to. I checked my bilge pump it works, my center tube is empty although we have had a lot of rain but I did see water coming out from underneath my boat quite often while was raining. That leaves me with linkage I sort of wondered about the linkage because there's a lot of play before the motor starts to really move how can I check the linkage without going to the dealer? I'm pretty handy I guess I take the motor cover off and see where goes. It is a brand-new boat and I tend to think that a brand-new boat probably has that stuff set up correctly but maybe I am naïve. I will definitely report back once I put the enertia prop on and test it out. Thanks again for all the advice I really appreciate it.

 

[craigmack]

Since you're switching from a Mirage Plus to an Enertia you may find this (old) article interesting

http://continuouswave.com/ubb/Forum4/HTML/006785.html

 

[trout74]

Craigmack,

Thanks for the link, that was a great read. I am excited to see the RPM difference with the same pitch prop. Hopefully it will be the missing link to my issue. I'm still interested if anyone knows how to check to see if I'm getting full motion out of my throttle linkage.

Thanks,
Trout

 

[craigmack]

Don't get too excited, you're not going to get a 1000 RPM increase. I've been meaning to check my linkage too though like you I'm not sure how to tell. I guess if the lever on the engine has different holes the cable can attach to would be something to look for though I'm not holding my breath on that being the case.

 

[The Rooster]

Good luck Graham. Hope this solves your issue !!!

 

[trout74]

Good luck Graham. Hope this solves your issue !!!

me too!

 

[MikDee]

If your linkage has a threaded brass barrel, on a threaded shaft on the cable ends, that's where to adjust length. Check it out.

 

[trout74]

If your linkage has a threaded brass barrel, on a threaded shaft on the cable ends, that's where to adjust length. Check it out.

Im assuming I do this on the motor side. Basically at WOT, shouldn't the butterfly air intake be completely Vertical, and then I should be receiving full throttle?

 

[trout74]

So i checked the linkage, it looks to be ok. When the throttle is pushed wide open at the helm, the butterfly is perfectly vertical, don't know how it could get anymore wide open than that. I did talk to a dealer today that puts Vengance props on his pontoons because they are smaller than the mirage and Enertia and spin higher RPMs. I'm waiting for the Enertia to show up and test it out. " fingers crossed "

 

[trout74]

Update.

I am happy to report that I am the proud owner of a 15P Enertia, and I LOVE IT! Craigmack and Rooster both suggested for me to try that prop. I have a whole new boat. I got 5600 RPM by myself and 5400 RPMs with 4 kids, the wife and all our gear. I clocked 35.8 MPH on the GPS with a full boat and gas as well. Those are numbers I can live with. you guys were right, the Enertia is a superior prop to the Mirage for my application. Funny thing is I could get 5400 or 5500 RPMs and the speed was actually a little faster at 5000 RPMs. when I trimmed it up to get more RPMs the speed dropped if I got higher than 1/4 trim up. 1/4 trim is fastest.

Thanks for all the advice and help.

Trout

 

[BrianMc]

Your faster at 5000 because your prop is slipping to 5400-5600 when you try to trim up higher. The higher rake is gaining you bowlift which brought your speed up,but now your riding higher too. If you can drop your motor a hole you'll be able to trim higher for more bowlift. Or try shifting weight back if your down all the way.

I'm turning a 16 at full trim with my motor on a hydr. jackplate. I have to drop the JP all the way down to keep it hooked up and the motor's water intakes in the water. At around 37-38 the bow really starts to lift which is where it runs with most loads. 40+ running light.