Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right????????

[cocky1421]

just bought a used pontoon bentely elite encore with the 115 opti max......... it feels sluggish and not performing well at all. It is spinning a 13.25 x 17p prop........ I looked on mercury website and it tested a 2008 bentely with the 115 with a 13.75 X 15 p gets it up to 29mph............. so where is the disconnect for my boat? it could be normal but I dont think it is. OH............ 5500 rpm at 24mph.

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

All tests are done lightly loaded, nothing flapping in the wind either. Where you getting your speed (speedo, GPS, etc) ?

What NAME prop did Merc use --Tempest, Fury, etc... 4 blades or 3? Can you link the test here, please?

Purely on pitch to RPM, you are fine. Also, the 13.75 x 15p must work better for the boat than yours, but that doesn't make yours wrong. Well, maybe a little wrong. Your pitch does seem to high if you want to get to max RPM.

They used a different prop. Unless you actually run that prop, in the conditions they ran it, etc. then you have a major variable not controlled for. Still, doesn't mean anything is broken.

Even the outside temp and humidity matter. Where do you live? Elevation matters, too.

Merc runs the snot out of their engines for a test. When they run for top speed, they're gonna run it to the top of the redline, and that means getting just the right prop on 'er. They're running the smaller Opt's to 6100 RPMs or more.

The hardest thing you might ever do is take on the actual engine builder. Merc ran the boat to demo their 115 ?? To compete with that, I would do EXACTLY what they did. You are going up against sheer brilliance, and they are going to do whatever they can to legitimately post the absolute highest speed.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

okay, year 2010, aluminum prop black max. GPS speed 24 mph, no chop no wind to speak of really. I also get no prop steer at all.

Link to test http://www.mercurymarine.com/engines/engine-tests/boat-house-bulletin/?ID=95&

I tested a 2008 24 ft 90 mercury 4 stroke stock and it got 27 GPS, dont know pitch size or anything else on that.

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Where do you live?

Also, the answer is the prop. It isn't complicated. 17p on your boat, even understanding the other differences, is too much. You are getting more prop slip. May be the prop or how the engine sits on your boat. Maybe she is too low.

Mercury Name Black Max
Diameter/ Pitch 13 3/4" x 15"

Get the same prop and run in same conditions with just 1/4 tank of fuel with engine mounted/set at optimum.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

South Carolina, Lake Murray. I am just very new to boating, never owned a boat never driven only been on one like 10 times and I did not pay attention to anything other than the pretty girls and beer. Sounds like I will get the same prop and go from there I just wanted yalls expert opinnion............. thanks this is why I join a forum.

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Okay, check back in. I would like to know how it works out. I checked your elevation, and it's just slightly higher than the test elevation, so it is coming down to just the prop size/type. Other than that, as long as the engine height is right and all other things are equal, it will probably work out.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

okay speaking to that how do you determine the proper engine height??????

 

[steelespike]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

On a pontoon engine height is based on the highest without ventilation (prop loses grip engine revs and boat slows).
Leave height alone for now.As suggested your prop has too much pitch. And the 15 suggested may be right. Unfortunately on a pontoon
Its hard to predict prop selection results.I checked some test results similar size toons same hp motor Speeds ranged from 22.9 to
to about 30 mph prop size 11" to 13"These motors ratios were slightly lower,( harder to turn requiring lower pitch props).
But the point is speeds are all over the place .Boats were all 22 ft one 20 ft.
The 15" prop in a 4 blade should work well.4 blade resist venting and give better control at the dock.
Once you have the prop get us a light load test run remind us of prop size.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

since I am brand new to boating..................... can you point me to a good solid prop manufacturer??????? and also stainless or aluminum????? I have heard things about both.

 

[steelespike]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Solas props have a good reputation and aluminum cost about 1/3 of a stainless
and can do an excellent job. Also cost less to repair and are more forgiving if you strike something.
You can get props right here at boats.
If your a new boater you should take a safe boating course and if you have a friend or relative that has experience
boating having them along will help you out. If your going to be launching go to and empty parking lot and practice backing.
You might stop by a local launch and ask someone not in the midst of launching any tips about the procedure and which ramp is best to launch from.

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

I would say aluminum is best for a 'toon, but if you are hellbent on top speed and can only sleep at night knowing you are running all out, then you'd have to go stainless steel.

I don't even talk people down off the top-speed ledge anymore (which is where I find most of them). The extremes people go to for 2-3 MPH is crazy when the engine is running in the top RPM range anyway. That's why I just tell people how to get there, and how to account for the most likely variables.

steelespike nailed one huge thing though, and that is how some Merc tests show a rather small pitch prop, which lets the engine/prop rev like the Dickens, and this in turn gives a bit more 'zip' at low-speed maneuvers.

And speed was still there on the top in some cases.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

thanks guys, took the boat out today had a blast topped out at 24.5 with three people coolers and all gear. I will try and prop it to the mercury specs....... I am NOT a speed junky its a pontoon but I would like to have some fun with it every now and then. No launching on the water but very close to everyone its a little nerve racking but once I get going easy peezy. just love to park it on the beach and relax it is pretty cool. I am all about safety so no issues there. Thanks for your help will check back in.

 

[steelespike]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Good luck.We'll be watching for your results.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

alright, bought a 13.75 15 p black max same one off of mercury's website. Gained 2mph but it shot up to 6300 rpms........ way over the spec 5750 that mercury says the 115 optimax should go. So I assume I will need to take this off. Also lost about 2-3 mph at crusing 3k 3.5k rpms. so whats next guys. These r just questions looking to get the best performance cruising specs I can. I know there are too many variables.

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Ain't that got a rev limiter that kicks in at 5800? 5750 redline with rev limiter at 5800. Theoretically, you can't rev it past 5800; its internal chip would block it.

Is your tach off? Might be. Might explain a lot of things....

 

[steelespike]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Not sure how we arrived at a 15" prop when we were already at 5500.Maybe I can't add and messed up.Granted slip was high at about 43% but pontoons do have high slip.I would think a 4 blade 17"
or 16"might reduce slip and get a little speed.1 or 2 mph should be considered excellent.
Maybe you can exchange the prop for a 16 or 17" 4 blade.I usually suggest sticking with a brand for predictability.
I do wonder if the Black Max is good match.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

well the tach definently red 6400 rpms at 27.46 gps no sort of rev limiter to speak of............ so IF it has a rev limiter in it......... then.......checked the owners manual and yeah it says it has a engine overspeed warning and it will limit the engines RPMS, also emitting a loud continuous beep. So knowing that I might have a miss leading Tach then?????? what now.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

specificly off of mercury's test sight for a 24ft toon with the 115, they used th 15 not the 17

 

[Philster]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

Your tach is wrong.

 

[cocky1421]

Re: Mercury 115, 22 ft pontoon lifting strakes. 13.25 x 17p 24mph sound right???????

okay................ so before I was severely over proped now I am proped better, sooooo my next question is how do I replace the tach, can I just plug and play a new one or is it more involved?????