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SLXJOE

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2022 SXL 18 with 60 horse mercury. Engine rpms top out at 3600, with 12.5 MPH. Returned to dealer that suggested giving more trim. I tried trimming out but had the same result. It appears that there is no throttle response until the throttle is moved to about 1/2 of the total forward travel. Once that point is met there is acceleration until about the last 1/4 of forward travel. After that point there is no additional acceleration. In reverse same with about 1/2 required before any increase in rpms.

There is a about 70 hours on the boat now.

The dealer said if trimming out didn't get me there then they would replace the prop, but It seems to me the problem is in the throttle.

Any suggestions or thoughts are greatly appreciated.
 
Searching List Your Specs Here, found:

HICKORY STICK's BOAT:

  • Boat Model --------- 22 SLi Extended Deck
  • Model Year --------- 2011
  • Tube Option -------- Two 25" Tubes
  • Power Option ----- Mercury 60hp Bigfoot
  • Prop Specs ---------- 14"x 10p
  • Performance ------ 18-19mph @ 6100rpm on GPS

Update: New Prop 14"x 11p 21mph @ 5850rpm on GPS

Smooth water, light wind, 1/2 Tank of fuel, 2 on board + the wonder dog.
 
What prop do you have now? Has it always been this way or is this a new development during its 70 hours of usage?
 
It was this way right from the initial break in period. The prop is a Black Max 13.75 diameter 15 pitch. Mercury website says with that set up should be 5750 rpm with 23.64 top end.
 
Sounds like way too much pitch for a 60hp.....looking at the specs posted above with 10 & 11 pitch options. Heck, I run a 14 pitch on my 150 and could realistically go to a 13 pitch.
 
DaveyJ said:
Sounds like way too much pitch for a 60hp.....looking at the specs posted above with 10 & 11 pitch options. Heck, I run a 14 pitch on my 150 and could realistically go to a 13 pitch.
Click to expand...

i have a 15p on my vmax 250.... granted, a 24' boat, but i might have too much pitch too, lol...
 
If you have the standard 1.8 gears, any 15p prop is WAY too much pitch. The motor is overloaded big time and can't turn normal RPM at anything like the speed you are getting. Even with the "CT" motor (also known as Bigfoot) and it's 2.33 gears, 15p is likely too much for 60 HP (unless slippage is pretty high). Maybe with the 60R (race) model on a light boat, a 15p would make sense.

With any "good" prop (meaning low slippage) and our 90 HP 2.33 gears, 15p is too much. Our 13p Quicksilver Nemesis or 12p Yamaha Talon (for heavy loads) are reasonable choices.

Yes, also check that the throttle lever is getting full travel at the motor. Also check for restricted fuel flow.
 
Last edited:
How do you check for full travel at the motor and is there adjustment?
 

This is from the Mercury website.​

YOUR SETUP​

  • Boat type: Pontoon
  • Usage: Overall good performance/0 ft
  • Engine Manufacturer:
    Mercury
  • Engine Type: Outboard
  • Engine Year: 2021
  • Number of Engines: One
  • Engine Family: FourStroke
  • Engine: 60 EFI 4cyl (995cc)
  • Drive / Gear Case: 40-60 HP FourStroke Command Thrust, 2.33 Ratio

DETAILS​

  • Calculated Pitch: 14.71
  • Calculated Weight with engine(s): 1,665.00 lbs
  • Calculated Engine RPM: 5,750
  • Calculated Boat Speed: 23.64 mph

RECOMMENDED PROPELLER FAMILIES (4) Results​


PropellerMaterialBladesDiameterPitchRotationPart #
Black Max®Mercalloy313.7515RH77342A45
 
I just went to check out the Merc prop selector. ALL their options seem to be way off and over-propped on at least pitch.

I’d recommend sticking with suggestions above and/or basing it on our Specs and Performance thread by people with similar size boats and motors.

I agree with others above. Pitch seems too high, and I’d be thinking 10-11, maybe a 12. Nothing more IMHO.

However, even with that prop correction made, RPM’s seem way low, and your throttle range seems off. I don’t have ideas on trouble shooting that outside of taking it into the dealership to get checked out for the throttle issue. That said, if you are handy, I am sure others can guide you on what to check and do in that regard too.
 
In your original post ,you stated that the dealer will change the prop. Will he water test with you ? Then he can check the throttle travel .
 
They don't water test. I may ask him for the different prop and change it myself. I really think I have a throttle issue as well as possibly prop pitch . Once you hit 3600 rpms the rpms don't change when adding trim at. Similarly the rpms don't drop while reducing the trim. I was hoping that there was a way to check the throttle range myself.
Thanks everyone for all the responses. You're a great group
 
I have Bennington prop chart that is supplied to dealers as a " starting point " for prop usage .
The suggested prop for your set up ( 18 ft 60 hp) is a 12 X 10.5 Black Max or a 13.8 X 11 Spitfire if you have the 60 Bigfoot
 
SLXJOE said:
How do you check for full travel at the motor and is there adjustment?
Click to expand...
Pretty easy really. Compare throttle lever travel with the relative travel of the throttle plate(s) under the motor cover. However, it might be best to get the prop right and see what happens to RPM/performance...there may be nothing wrong with the motor or setup.

23 MPH might be possible if 60 HP will turn an 11p Nemesis to ~5950 RPM. Worth noting that speed for pontoons like ours is VERY sensitive to weight. Expect 23 is only possible with a light load. See slip calculator below:

https://www.mercuryracing.com/prope...html?msclkid=9cab1a603c991760143178af45e3e327
 
I put my data in the calculator from the link you provided, and it verified what you all have been recommending. The prop is a problem. The slip value with my prop is 41 with a recommendation of less than 20. I will call my dealer today about getting a 13.8 X 11 Spitfire prop.
Thanks again for everyone's input
 
The results are in! I got the new 13.8x11 prop. Installed this morning and tested it out. The lake was calm with little or no wind. I washed the pontoons last evening. We were carrying about 1/2 tank of gas with me and my wife on board. The two of us contributed about 300 lbs to the total weight.
I completely trimmed out until the boat began to porpoise.
Max rpms 5200
Top speed 17 miles per hour.

This is a big improvement over the 3600 rpm 12.5 MPH with the 15 prop but still is on the lower end of bottom rpm and mph.
 
That still sounds low . I got 28 on a 22 SLX with a 90 .
What hole is your motor mounted ?
 
SLXJOE said:

This is from the Mercury website.​

YOUR SETUP​

  • Boat type: Pontoon
  • Usage: Overall good performance/0 ft
  • Engine Manufacturer:
    Mercury
  • Engine Type: Outboard
  • Engine Year: 2021
  • Number of Engines: One
  • Engine Family: FourStroke
  • Engine: 60 EFI 4cyl (995cc)
  • Drive / Gear Case: 40-60 HP FourStroke Command Thrust, 2.33 Ratio

DETAILS​

  • Calculated Pitch: 14.71
  • Calculated Weight with engine(s): 1,665.00 lbs
  • Calculated Engine RPM: 5,750
  • Calculated Boat Speed: 23.64 mph

RECOMMENDED PROPELLER FAMILIES (4) Results​


PropellerMaterialBladesDiameterPitchRotationPart #
Black Max®Mercalloy313.7515RH77342A45
Click to expand...

It didn't compensate for the engine weight, people, and gear...this is assuming that you do have the 60CT with the 2.33:1 DR.
See if your dealer will let you try out that SS Vengeance listed at the bottom of the screenshot:



Merc60CT prop options 18SXL.png
 
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