Pontoon boat speed

[Leisurekraft]

My last boat was a 24' Lowe pontoon with a 115 hp Johnson 2 stroke outboard. I can't remember exactly but I think it would get up to about 30 mph with just me in the boat and clean pontoons. Once in a while I'd have to scrape the pontoon clean because overtime algae would accumulate and slow it down by 10 mph. I just bought a used 24' Leisure craft with a 115 hp Susuki 4 stroke. When I test drove it it only got up to about 20 mph so this weekend I cleaned the pontoons. After cleaning, I only gained 2 to 3 mph. This is slower than I expected. The tach is not working so I don't know the rpm's. and I also don't know what pitch the prop is. What speed should I expect?

 

[BatDaddy1887]

Re: Pontoon boat speed

First of all, you absolutely must fix/replace your tach to adjust your speed. Secondly, you may want to try different props on the new boat as most times that's the problem. Your Tach will indicate how many RPMs you are getting with each different prop. Find a boat shop where they will let you try different props and start there (you could even try your spare prop to start with).

 

[Tompen]

Re: Pontoon boat speed

20 mph is definitely slow for a 115. It sounds like its probably the prop. Either that or a motor/fuel issue. I have a 1989 24' pontoon (made by Suntracker I think) with a 96' evinrude 115 hp and I get up to 27-28 mph, and thats with the wrong prop, some ventilation problems and dirty pontoons.

You need to find out what prop you have. You probably will want around a 3 blade 14x13 prop or a comparable 4 blade prop. I'd be curious to hear what prop you go with and how it performs (since I have a similar boat/motor and also need a prop).

Probably a stupid question, but how did you clean your pontoons? Would it be possible to do it when its in the water?

 

[bldtrailer]

Re: Pontoon boat speed

20 mph is definitely slow for a 115. It sounds like its probably the prop. Either that or a motor/fuel issue. I have a 1989 24' pontoon (made by Suntracker I think) with a 96' evinrude 115 hp and I get up to 27-28 mph, and thats with the wrong prop, some ventilation problems and dirty pontoons.

You need to find out what prop you have. You probably will want around a 3 blade 14x13 prop or a comparable 4 blade prop. I'd be curious to hear what prop you go with and how it performs (since I have a similar boat/motor and also need a prop).

Probably a stupid question, but how did you clean your pontoons? Would it be possible to do it when its in the water?

i use a plastic scraper to clean the growth off of the pontoons

 

[Mi duckdown]

Re: Pontoon boat speed

Leis. need to get tach working an GPS speed. without that No one can really help, MHO.

 

[Leisurekraft]

Re: Pontoon boat speed

I use a straight razor blade in a holder and use a very steep angle to clean the pontoons in the water. After cleaning I only achieved 23 mph on a GPS. I don't know what the prop is yet I was hoping cleaning would give me the speed I expected. I'll have to take it off in the water since I don't have a trailer. I don't know why the tach isn't working but ill need to resolve that too of course. Other than that the engine runs smooth and quiet I just don't know what the rpm's are.

 

[Bamaman1]

Re: Pontoon boat speed

Most twin hulled pontoons with 115 hp will top out at about 25 mph when propped right. Few have ever seen 30 mph without lifting strakes. A 13 pitch prop is probably the right size, if not an 11 pitch prop. It all depends on if your boat pulls the maximum published redline rpm's of the engine. You might find a tach on EBaymotors.com or Boattrader.com's parts listings.

Assign each passenger a ScotchBrite cleaning pad. You can even buy them for marine use with a plastic handle on them. Tell them you'll move on down the lake as soon as they get the bathtub ring off the toons. Cleaning is not that bad a job if done often.

I have not had a trailer for the past 25 years, and really missed going to other lakes in a 100 mile circle. My home lake is fabulous, but there are other great lakes I'd like to see. If your boat is late model, a trailer is really nice to have.

 

[MaPaHa]

Re: Pontoon boat speed

^^^ What he said on the scotchbrite pads. Come on in, the water's fine, we'll go for a ride when the toons are clean.

I cleaned mine with several on them up on on blocks only because I was working on the trailer but it would have been easier on the lake this time of year.

 

[Leisurekraft]

Re: Pontoon boat speed

Thanks for all the advice. I'm going to work on the tach issue first. Could it be that it's just a problem with the gauge and I should replace it first?

 

[MH Hawker]

Re: Pontoon boat speed

delete double post

 

[MH Hawker]

Re: Pontoon boat speed

Is the battery charging if it is then it may be just the tach, I am not familiar with that year Johnson but most techs are driven by the charging system and if its charging then its in the wiring or the tach its self and it may be as simple and the pole/pulse switch on the back and moving it around back and fourth to clean the contacts can revive it, after making a note on what pole setting it is on now. You can also see if its getting voltage on the signal wire.

 

[Leisurekraft]

Re: Pontoon boat speed

I ordered a new tach. The existing tach is stuck at 100 rpm and doesn't move at all when the motors running. I'll check the wire leads for DC voltage.
Thanks

 

[Leisurekraft]

Re: Pontoon boat speed

I installed a new tac and cleaned the pontoons again so now I'm running 24 mph on a GPS. The motor tops out at 5500 rpm and I have a 3x14x17 prop. How many rpm's should this Suzuki 115 4 stroke top out at?

 

[Rancherlee]

Re: Pontoon boat speed

5500-5800 is a good target for a DF115, the 17 pitch prop has me worried though as you are seeing 30%+ slip. These suzuki engines have a big gear ratio giving them a ton of torque at the prop which makes it hard for the prop to get enough bite on a pontoon. A 14" diameter 4 blade 13 or 15 pitch is a better match for your setup, your current prop would push a V-hull to ~ 35mph @ 5500rpm and your only seeing 24mph

 

[The Woo Woo Kid]

Re: Pontoon boat speed

.....the 17 pitch prop has me worried though as you are seeing 30%+ slip.

Newb here. 1st season.

Slip ? Hmmm. Ok my pontoon, 22ft, 26 in toons w/strakes and a 135 Opitmax may also be in the " slipping " range.

The Opti is sporting a 14.5 x 19 pitch 3 blade. WTO 5200 rpms....Engine's range 5,000 - 5,500 rpms.

I don't know my top speed yet, no speedo, but Boating World did a test on the exact seem boat/motor as mine and got 42 mph which I don't believe I'm getting......Prop Slip ?

 

[Rancherlee]

Re: Pontoon boat speed

Slip is the percent of speed lost between calculated speed and actual speed. Many V hull boats run in the 10% or less range and even some straked tritoons can get into this range. Regular 2 toon pontoons usually fall in the 20-30% range due to the motor running in the turbulent wake created between the pontoons. My home built tritoon is pulling an efficient 6% as calculated speed is 31mph@6100rpm and it will run 30mph with JUST ME, before adding the 3rd toon It only ran 23mph with just me and the same prop which is 26% slip. Fully loaded with 7-8 adults pulls me down to 22mph@5200rpm which is 20% slip as calculated speed is 26.5mph @ 5200rpm.

 

[WaterDR]

Re: Pontoon boat speed

30% slip is not uncommon on a non-planing pontoon. You can't compare slip % on a toon to other boats or even from toon to toon. A toon with a 200 hp motor and lifting strakes that can plane will see low slip %'s like a V-hull. Just my $0.02

 

[WaterDR]

Re: Pontoon boat speed

Newb here. 1st season.

Slip ? Hmmm. Ok my pontoon, 22ft, 26 in toons w/strakes and a 135 Opitmax may also be in the " slipping " range.

The Opti is sporting a 14.5 x 19 pitch 3 blade. WTO 5200 rpms....Engine's range 5,000 - 5,500 rpms.

I don't know my top speed yet, no speedo, but Boating World did a test on the exact seem boat/motor as mine and got 42 mph which I don't believe I'm getting......Prop Slip ?

Those numbers don't seem coreect to me. 42 MPH on a 22' foto toon with a 135 seems way off.

 

[Leisurekraft]

Re: Pontoon boat speed

So 5500 RPM's is good. My understanding is less pitch on the prop will cause more slip and over rev's on the engine. Will more pitch bog down the engine or will it reduce slip and increase speed but still maintain 5500 rpm's?

 

[BobGinCO]

Re: Pontoon boat speed

You should be able to hit AT LEAST 120...if you push it off the back ramp of a C-130 at 20,000 feet.