New Prop for 40 hp Johnson on 16' Pontoon

vtbowfishn

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Jun 17, 2016
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OK I have a 16' 1991 Tracker Bass Buggy that I stripped down and re decked a few years ago. I put all new furniture on it completely changing it from it's original state. I also added a raised deck on the front for bow fishing. It had originally come with a Johnson 28 HP Special and the lower unit got a hole in it from some granite rocks. I purchased a 1990 40 HP Johnson 2 cylinder 2 cycle with the small gear box. It came through with a 3 blade 12 1/2" 13 pitch Aluminum Prop. This year I finished the project adding the 3rd pontoon to the center. I cut down a new 18' 24" log that was pulled from a brand new pontoon boat that got road rash on the pontoon when the dealer was bringing it back from a boat show. I cut the pontoon to 13' and added a cross between lifting strakes and tap fins to it, more like a longer water glide. I finally got the Tach on it to check it out, but before I got it hooked up I ordered 2 Props I guessed would work, figuring the 12 1/2 13 was over propped and based off info found on Prop Mfg sights. Not even close. The prop I had was not as bad as I thought the RPM with just me on it came up to 5100 RPM and 22 mph, the WOT for that motor is 4500 - 5500. I usually have quite a load on it so I decided to check out the Vortex 4 blade 11 1/2" 9 pitch. I knew it would probably go above the 5500 but I figured with the 4 blade it would not go past 5800 with just me on it. Wrong again I gave it some throttle and it seemed to just sit and spin churning the water with hardly any push. I gave it more throttle and it spun up to 6300 RPM with more throttle to go. Bad match for the boat and motor. The smaller Dia. had a bigger effect on it than I thought it would. I guess someone will get a good deal on Ebay when I list it New used prop with less than 3 minutes use.
So any ways I ordered a Michigan Match aluminum that is the same as the 3 blades Johnson used on that motor, only I went to the 13" 11 pitch that should get me to 5500 or close, with more push larger diam by 1/2" and yes it will clear by 1/4" and it is the same as a Factory Johnson Prop.
Back to the 3rd pontoon, it came up quickly and planed out flat, I do have a Hydo foil fin on the Motor and that brings it up fast. The nose no longer dives when I kill the throttle as I positioned the pontoon about 18" ahead of the other 2 21" logs. With just me on it, it leans a bit on sharp corners not banking like a lot of tri toons. I took it out today and tested it with 3 other people and myself about 700 lbs I had 24 gal of fuel and I also have 3 deep large cell batteries on it. It would get up to 18 MPH but not come completely out and plane flat even with the extra people towards the front. It did tend to handle better with the extra weight. RPM still came up to between 5000 and 5100. I think the new 13 - 11 will work out well.

Oh yeah hello every one I am new here, but have read many post over the last few years.

Shane from Vermont.
 

vtbowfishn

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Jun 17, 2016
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Today I tested out the Michigan Match 13" X 11 Pitch blade, RPM came up to 5400 and 25 MPH with just Me 260 lbs and 24 gals of fuel, 3 large deep cell batteries. Seemed to have good pull and came up fast compared to the 12 1/2 " X 13 Pitch.
I then tested it out with 6 extra people 1000 lbs more. RPM came up to 4600 - 4700 with a top speed of 14 MPH. Next 2 people got off, 350 lbs less weight, RPM came up to between 4900 - 5000 and MPH came up to 19 - 20.
 

vtbowfishn

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Jun 17, 2016
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I am still looking for a bit more push at heavy load so today I ordered 2 Turning Point Props and one hub.

One is a Turning Point H2-1208 Hustler Aluminum 12.5" x 8 pitch 3 Blade, the other is is a Turning Point H2-1210 Hustler Aluminum 12" x 10.5 pitch 3 Blade.

It would not bother me if with just me the WOT came up to 5800 RPM as long as with me and 3 others it stays below 5500 RPM, many times when we go out we end up with more people so if I can get more out of the boat loaded I would be happy.

I read here on this sight that the Turning Point Props are quite aggressive so the Pitch is equal to a higher pitch in some other Mfgs Props. We will find out.
 

Sea Rider

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Sep 20, 2008
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12,345
Can't possibly dial a top performer prop for multiple weight requirements when boating at wot. Probably a 40 HP is a underpowered engine for that size toon. Which is the max passsenger and HP rated for ?

Happy Boating
 

vtbowfishn

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Jun 17, 2016
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Yes, what I want is problematic, that is why I am looking for a prop that will work well with heavier weight, I will swap out props if I have to on the days I know the load will be greater. I am hoping for one of the 2 TP props I ordered will fit the bill for heavier loads.
The Pontoon has a 40 HP max listed because it only had 2 16' 21" logs I added the 3rd 13' 24" log which greatly aided floatation and performance. I use the boat to Bowfish and only want the extra speed to get from spot to spot on the lake without taking as much time. It is not the same as my old airboat I built years ago, but it meets the noise regulations set for Lake Champlain here in Vermont.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
You can stay with the prop that gives the max wot rpm, ideally at prop that will produce max wot rpm when heavily loaded, when with lighter load, just throttle less while watching tach as not to over rev. Swaping props for different boating loads is a PITA.

Happy Boating
 
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