Best way to gain a little speed with 40hp engine

[cmon74]

I just picked up a 2018 sun tracker 16 dlx fishing buggy with a 40 hp Bigfoot engine. The boat and engine has less then 50 hours on it. I'm getting around 16-18 mph according to gps. I know this pontoon ain't gonna win any races but Is there any modification that can be done to improve this slightly? What would be the best prop to run on this engine? Thank you!

 

[Scott Danforth]

the prop on there is probably best. does it allow the motor to go to WOT RPM?

only way to get any 2-log pontoon moving faster is to add a 3rd log, add lifting strakes to all the logs, and add a lot more hp.

BTW, your pontoon boat will move between 16-18hp with anywhere between a 25-60hp motor. until you change the physics and can get the boat from pushing water to flying on top the water, there is not much you can do.

a good example - an 18' suntracker bass buggy with a 60hp only moves 18 mph


you are dealing with displacement speed of a twin-log pontoon which is limited by the length of the boat

so back off the throttle (because it isnt going to go any faster), crack a cold one, turn up the tunes and enjoy the water.

 

[matt167]

Easiest way is to replace the 16’ pontoon with a 16’ fish and ski. You’ll gain 10 mph on the low side. To go above displacement speed, you need to get ontop of the water. The boat needs to be able to climb its own wake. A pontoon without lift strakes and a lot of hp won’t do it. Back in the day, pontoons came with 20-30hp and that was enough.

 

[cyclops222]

NEVER buy any poontoon boat. Without speed testing it. With a full NORMAL load of people and gas tank. Add 1 extra person to take the place of a full tank of gasoline, food and drink coolers, anchor and rain covers.
Do not even waste time trying to get the boat level. Why ? People will form little groups in different parts of the boat. 4 fatties in the bow and left corner. Everyone right next to the driver. bow in the air. With water going inside of the motor.
Poontoons are FANTASTIC tied up to the dock. Suncover up. And a golf cart to shuttle people of all ages back and forth to the house. For a toilet, food and drinks or having had enough sun.
That is when a poontoon is fantastic !!!
How a friend uses his poontoon.
They are terrific for some handicapped people.

 

[jlh3rd]

everything above is correct. I'll add:
you didn't say what your WOT rpm is currently.
If you're at max rpm, then maybe reducing the pitch by 1 inch MIGHT get you an increase of 1-2 mph. Emphasis might.
Torque is a measure of how much work you are doing (pushing a boat)
HP is a measure of how fast you want to do it..
physics is physics.

 

[cmon74]

NEVER buy any poontoon boat. Without speed testing it. With a full NORMAL load of people and gas tank. Add 1 extra person to take the place of a full tank of gasoline, food and drink coolers, anchor and rain covers.
Do not even waste time trying to get the boat level. Why ? People will form little groups in different parts of the boat. 4 fatties in the bow and left corner. Everyone right next to the driver. bow in the air. With water going inside of the motor.
Poontoons are FANTASTIC tied up to the dock. Suncover up. And a golf cart to shuttle people of all ages back and forth to the house. For a toilet, food and drinks or having had enough sun.
That is when a poontoon is fantastic !!!
How a friend uses his poontoon.
They are terrific for some handicapped people.

I disagree about buying pontoon boats. They are in my opinion the all around best fishing boat you can buy. I was just curious about tweaking the engine. I read somewhere along the lines about taking out the restrictor and replacing the ecm. That would essentially turn my 40 hp into a 60hp. On top of that, changing out to a better prop. From my understanding, the 40hp Bigfoot and the 60hp are the same exact size and weight. I was hoping to get more info from here regarding that. My WOT rpm's is around 5200-5300 with passengers. This pontoon gets on plane well less then 30 seconds fully loaded. Sorry I left that out. And I really do appreciate everyone's opinions and input. I sold my 1994 chaparral deck boat with a beast 5.7L engine. I sure do miss her. But I love to fish

 

[cmon74]

the prop on there is probably best. does it allow the motor to go to WOT RPM?

only way to get any 2-log pontoon moving faster is to add a 3rd log, add lifting strakes to all the logs, and add a lot more hp.

BTW, your pontoon boat will move between 16-18hp with anywhere between a 25-60hp motor. until you change the physics and can get the boat from pushing water to flying on top the water, there is not much you can do.

a good example - an 18' suntracker bass buggy with a 60hp only moves 18 mph

View attachment 400437
you are dealing with displacement speed of a twin-log pontoon which is limited by the length of the boat

so back off the throttle (because it isnt going to go any faster), crack a cold one, turn up the tunes and enjoy the water.

Best advice I've heard in a long time. And great info on the speed chart you posted. Ty

 

[Scott Danforth]

I was just curious about tweaking the engine. I read somewhere along the lines about taking out the restrictor and replacing the ecm. That would essentially turn my 40 hp into a 60hp. On top of that, changing out to a better prop. From my understanding, the 40hp Bigfoot and the 60hp are the same exact size and weight. I was hoping to get more info from here regarding that.

other than spending lots of money and burning more fuel. what would you want to accomplish attempting to swap ECU's and parts? your pontoon wont go any faster.

 

[cmon74]

other than spending lots of money and burning more fuel. what would you want to accomplish attempting to swap ECU's and parts? your pontoon wont go any faster.

It might not and I'm fine if it doesn't. I just wanted to get some input. My last 2004 pontoon had a 40 hp 2 stroke and gps pegged it at 25 mph. But I do believe this 2018 sun tracker is a bit heavier

 

[jlh3rd]

The 60 hp, merc, big foot, 4 stroke, efi, pushed my '06, 24' twin tube pontoon at a max of just under 21 mph on a cold, late winter day, just me.
The same boat gets about 26 mph under similar conditions with a 2021 merc, 115 hp, CT @ 5800 rpm. With a one pitch lower prop, my rpm can touch 6100 but speed is around 23mph. But I can pull teens on tubes.
Max rpm's on my mercs are 6000. Yours should be the same, so your 700 rpm's. from the max. and at the low end.
If you lowered your pitch, your rpm will increase, more speed, questionable.

curious how long your '04 pontoon was.

 

[cmon74]

The 60 hp, merc, big foot, 4 stroke, efi, pushed my '06, 24' twin tube pontoon at a max of just under 21 mph on a cold, late winter day, just me.
The same boat gets about 26 mph under similar conditions with a 2021 merc, 115 hp, CT @ 5800 rpm. With a one pitch lower prop, my rpm can touch 6100 but speed is around 23mph. But I can pull teens on tubes.
Max rpm's on my mercs are 6000. Yours should be the same, so your 700 rpm's. from the max. and at the low end.
If you lowered your pitch, your rpm will increase, more speed, questionable.

curious how long your '04 pontoon was.

I'm thinking my max rpm may be 7000. But I could be wrong. But I know it's at least 6k. I'll have to look tomorrow. I'm needing a new prop. Would you have any recommendations on a good prop and pitch you could steer me towards? Thank you

 

[cmon74]

The 60 hp, merc, big foot, 4 stroke, efi, pushed my '06, 24' twin tube pontoon at a max of just under 21 mph on a cold, late winter day, just me.
The same boat gets about 26 mph under similar conditions with a 2021 merc, 115 hp, CT @ 5800 rpm. With a one pitch lower prop, my rpm can touch 6100 but speed is around 23mph. But I can pull teens on tubes.
Max rpm's on my mercs are 6000. Yours should be the same, so your 700 rpm's. from the max. and at the low end.
If you lowered your pitch, your rpm will increase, more speed, questionable.

curious how long your '04 pontoon was.

My 2004 was 16 foot as well.

 

[cmon74]

The 2004 was 16 foot as well but a lot lighter. I could pick it up by the trailer tongue and move it around in the yard. I can't quite do that with this 2018 bass buggy

 

[jlh3rd]

propping...It depends...and can get expensive.....I'm not one to steer anyone to a particular prop or what exact pitch you have to get. I can give you what I've learned and experienced.
Engines have an operating rpm range, my mercs are 5-6000. You need that knowledge,
After getting my new 115 merc., the 4 blade 14x14 prop maxed at 5800 rpm, 26+ mph. just me on board. Add teens on tubes and people on board, I'd see about 5300 rpm, not good for performance, and too low for me at max throttle.
Ended up with a 3 blade 16x12. That gave me 56-5700+ rpm under load, made the teens happy. But top speed, by myself, hard to see 23 mph and could bump the rev limiter sometimes.
Everything is a trade off, there is no magic prop, I know of...that's my point.
so, you can prop your boat to get max rpm when light...more speed..
or prop for torque, max rpm when loaded down like I did, when heavy...but lose speed.
to increase rpm's by 2-300: decrease pitch by 1 inch, or decrease diameter by 1 inch, or remove a blade.
And I'm not counting cupping, extra cupping, different blade designs, etc.
rpm's too high -do the opposite.
All my props are mercury aluminum.......
I don't think your merc. is rated to 7000.
so your 700 rpm from max throttle with people......so decrease the pitch by 1 inch which could give you about 5600rpm's ....then by your self you would see max rated or close. you will not see massive speed increases.

 

[cmon74]

propping...It depends...and can get expensive.....I'm not one to steer anyone to a particular prop or what exact pitch you have to get. I can give you what I've learned and experienced.
Engines have an operating rpm range, my mercs are 5-6000. You need that knowledge,
After getting my new 115 merc., the 4 blade 14x14 prop maxed at 5800 rpm, 26+ mph. just me on board. Add teens on tubes and people on board, I'd see about 5300 rpm, not good for performance, and too low for me at max throttle.
Ended up with a 3 blade 16x12. That gave me 56-5700+ rpm under load, made the teens happy. But top speed, by myself, hard to see 23 mph and could bump the rev limiter sometimes.
Everything is a trade off, there is no magic prop, I know of...that's my point.
so, you can prop your boat to get max rpm when light...more speed..
or prop for torque, max rpm when loaded down like I did, when heavy...but lose speed.
to increase rpm's by 2-300: decrease pitch by 1 inch, or decrease diameter by 1 inch, or remove a blade.
And I'm not counting cupping, extra cupping, different blade designs, etc.
rpm's too high -do the opposite.
All my props are mercury aluminum.......
I don't think your merc. is rated to 7000.
so your 700 rpm from max throttle with people......so decrease the pitch by 1 inch which could give you about 5600rpm's ....then by your self you would see max rated or close. you will not see massive speed increases.

It's all starting to make sense. I'm going to pay particular attention next time out. For what I got, 16-18 mph with load is good enough I suppose. It gets me to the big catfish holes lol. Thank you for all your help

 

[Scott Danforth]

I'm thinking my max rpm may be 7000. But I could be wrong. But I know it's at least 6k.

When I looked it up, the RPM was 5500

 

[jlh3rd]

so if your max throttle rpm is 5500, at 5300 you're kinda there.

ya wanna go fast? Get one of these. lol

 

[Scott Danforth]

If you want to go fast in a pontoon..... Get one of these.

A 25 foot sport toon with twin 450Rs. Then you can go to 80mph

 

[jlh3rd]

oh yeah...go fast, burn gas.

I wonder if enough air could get under that toon and flip it at speed.

 

[Scott Danforth]

oh yeah...go fast, burn gas.

I wonder if enough air could get under that toon and flip it at speed.

no, not even at 108mph. they are too heavy and there is not enough surface area under them to lift it to the point of flipping