Would like max performance for top speed

[JEFFBUZZZ]

just bought a 2012 suntracker 20ft fishing pontoon with a mercury 60 h.p big foot took it out yesterday with 3 people on board could only get 5600 rpm at wot top speed was 22 mph .with 7 people on board wot was 4800 rpm at 14 mph the prop is a 11 pitch .can i get any better top speed by changing prop .if i go to a 10 pitch will it only get better with heavy load ,and loose top speed with light load ,iam a prop dummy so i might be asking dumb questions .

 

[steelespike]

Re: Would like max performance for top speed

Speed is right on; rpm maybe a touch low. The tests i looked up rpm ranged from 5750 to 6000 oddly 5750 was with a 10" prop
didn't note the material,rest were 11" pitch speeds were 20-22.
7 people is probably over 1000 lbs Could be quite a bit over.Weight balance is important both front to back and side to side.
Probably won't gain much though.
a 10" could add 100 to 200 rpm. Hardly worth the investment.You might play with the setup a little.
On a pontoon I've seen lowering the motor improve speed and raising the motor also improve speed.
Motor trim is usually just to get the setup with the least ventilation.
Is the motor fully broken in?
Don't assume because its new that the throttle opens all the way or the height is ideal.
If you mostly run with a big load you might consider the smaller pitch though I wouldn't want to live on the difference if any.
Best way to gain any real speed is to skin the bottom or add a water glide( I think its called)kind of a third log
Boat is said to perform almost like a runabout.

 

[Jlawsen]

Re: Would like max performance for top speed

Speed is right on; rpm maybe a touch low. The tests i looked up rpm ranged from 5750 to 6000 oddly 5750 was with a 10" prop
didn't note the material,rest were 11" pitch speeds were 20-22.
7 people is probably over 1000 lbs Could be quite a bit over.Weight balance is important both front to back and side to side.
Probably won't gain much though.
a 10" could add 100 to 200 rpm. Hardly worth the investment.You might play with the setup a little.
On a pontoon I've seen lowering the motor improve speed and raising the motor also improve speed.
Motor trim is usually just to get the setup with the least ventilation.
Is the motor fully broken in?
Don't assume because its new that the throttle opens all the way or the height is ideal.
If you mostly run with a big load you might consider the smaller pitch though I wouldn't want to live on the difference if any.
Best way to gain any real speed is to skin the bottom or add a water glide( I think its called)kind of a third log
Boat is said to perform almost like a runabout.

Excellent advice.. I worked with a guy a while back on a nearly identical problem. IMHO he was expecting a toon to be as responsive as his bowrider and that just isn't going to happen with a conventional toon. We finally went with the third log and that not only increased the surface area for better lift but it got rid of the garbage water that the prop was running in. He ended up with a respectable 35mph top speed with a light load but it was a lot of money just for a few mph more.

My advice, leave it an enjoy the relaxing cruises.

 

[JEFFBUZZZ]

Re: Would like max performance for top speed

Speed is right on; rpm maybe a touch low. The tests i looked up rpm ranged from 5750 to 6000 oddly 5750 was with a 10" prop
didn't note the material,rest were 11" pitch speeds were 20-22.
7 people is probably over 1000 lbs Could be quite a bit over.Weight balance is important both front to back and side to side.
Probably won't gain much though.
a 10" could add 100 to 200 rpm. Hardly worth the investment.You might play with the setup a little.
On a pontoon I've seen lowering the motor improve speed and raising the motor also improve speed.
Motor trim is usually just to get the setup with the least ventilation.
Is the motor fully broken in?
Don't assume because its new that the throttle opens all the way or the height is ideal.
If you mostly run with a big load you might consider the smaller pitch though I wouldn't want to live on the difference if any.
Best way to gain any real speed is to skin the bottom or add a water glide( I think its called)kind of a third log
Boat is said to perform almost like a runabout.

Motor is not fully broke in ,bass pro is giving me the option to change prop at no cost to me so i want to take advantage of it if i need to .how will i know if i need to raise or lower the motor .i did notice when heavy load was on it ran faster by 2 mph with trim all the way down .when light load ran faster trimmed up .i will be skinning the bottom shortly and am looking into waterglide .thanks for all the help

 

[steelespike]

Re: Would like max performance for top speed

On a pontoon it's hard to tell because too deep can create problems with venting as much as not deep enough.
On a pontoon I wouldn't expect much speed difference just the prop running cleaner with less disturbance.

 

[JEFFBUZZZ]

Re: Would like max performance for top speed

On a pontoon it's hard to tell because too deep can create problems with venting as much as not deep enough.
On a pontoon I wouldn't expect much speed difference just the prop running cleaner with less disturbance.

are there any test i can do to determine if i need to lower or raise the motor to get the prop to run cleaner ,and would that help with fuel economy or ride comfort or what ,iam new to this and i am one of those guys who like to make a better wheel ,sometimes thats a good thing sometimes not.lol

 

[steelespike]

Re: Would like max performance for top speed

In the course of handling if the prop seems to have a good grip no change is needed.As far as economy any improvement
would be difficult to measure unless the original setup was noticeably poor.

 

[JEFFBUZZZ]

Re: Would like max performance for top speed

In the course of handling if the prop seems to have a good grip no change is needed.As far as economy any improvement
would be difficult to measure unless the original setup was noticeably poor.

went to bass pro today ,they recommended a 9 so i swapped the 11 out for a 9 will try it tomarrow on the river and go from there ,i have to give bass pro credit they have been great after the sale if i dont like the 9 i can go try different props till iam happy ,i thought that was pretty cool of them ,not alot of places would give you brand new props to try till u find one you like .

 

[JEFFBUZZZ]

Re: Would like max performance for top speed

ok here is the latest went out yesterday only four of us on the boat with the 9 pitch it got out the hole very fast but i lost speed badly went from 22 to 15 mph and rpm was 6300 at wot ,could not trim motor up any with out losing speed if i trimmed up any i would lose speed fast .there has to be something i can do to get max speed with max rpm .iam only shooting for 25 mph ,thats what i told bass pro i wanted this was the motor they recommended for that speed. iam 3 mph off with the 11 pitch .should i just settle for the 22mph or is there something i can do

 

[Philster]

Re: Would like max performance for top speed

Um... you were close to 25 lightly loaded. Speed ratings are based on something like 1/4 tank, 1 person, light gear and ideal air temps and decent humidity @ sea level elevation. You are okay on elevation.

These rob performance:

GA is hot.
GA is humid.
You hade three people
How much fuel?
How much gear?

Heat, Humidity, Weight. All rob performance.

5500-6000 RPM is the max of the RPM range based on Merc's site. Based on your initial test, you should have moved to a 10p prop, but technically you were ok. We just know your intent to load it more.

The dilemma: You can't have a perfect prop. More-so than almost any typical boat out there, your prop selection will never be perfect. If you prop it for 2-3 people and get 5800-5900 RPM w/ 10p prop that's sweet.... but you can actually carry a serious extra people/gear load (because it's a toon) that will probably drop the RPM at WOT to less than 5500.

Guess what? You can't zoom around or push the throttle all the way forward with a big load. Like towing a boat with a truck... Man, it's not gonna pull like it's not loaded! Not unless you change props as the needs change. In a truck, you can't grab a rear gear and swap it out on a whim.

You should: Put a 10p on there and take it very easy when she is loaded up, OR put a 10p on there and have a 9p ready for when you are loading up to make it a party barge.

Still, y'aint gone zooming around loaded up. Heck, if I load all 9 people my boat is rated for, I am not leaning on my throttle anymore than is needed to get on plane nicely. I mean, let's be real. Something has to give.

 

[steelespike]

Re: Would like max performance for top speed

I say leave well enough alone.Get it well broken in then strip it bare of any weight. Trim and balance it carefully
and take it out on a cool calm morning, try it with the gates opened and closed in various combinations.