Adding Third Toon to 24' Pontoon

[HogHeadSena]

I have a 2004 24' Pontoon with 25" Toon's and it currently has 90 hp 2 stroke Mercury. I am wanting to install a third toon and upgrade the motor to possibly a 250hp or 300hp. Has anybody ever had any experience with installing a third toon and will the Transom style units (that I am seeing on the internet for sale) handle a 300hp outboard? This will be my first run at a project like this? Any pointers will be appreciated.

 

[ahicks]

Sounds like an interesting project. I would talk to the 3rd 'toon manf. and get their thoughts regarding hp capacity. I'd also talk to them about ideal 3rd 'toon diameter. A larger diameter toon might help it turn easier.

And spray rails to add some lift, getting as much hull out of the water as quickly as possible.....

 

[HotTommy]

If you do this, I'd like to see progress reports along the way. I've also considered this possibility.

 

[doviebock]

Sounds like an interesting project. I would talk to the 3rd 'toon manf. and get their thoughts regarding hp capacity. I'd also talk to them about ideal 3rd 'toon diameter. A larger diameter toon might help it turn easier.

And spray rails to add some lift, getting as much hull out of the water as quickly as possible.....

Thanks.

 

[catman977]

Thanks.

You Might consider an IO for the 3rd Toon, I've seen it done with a small block Chevy. 400 Cu.

 

[WrenchMike]

I’d be interested to see your progress as I’m starting a similar project. I have a 1984 Lowe Sunbird 24’ with a 60hp Yamaha. It has u-shaped tubes. I’m planning on adding a third tube, lifting strakes and a Mercruiser 260. Thus far I have the i/o and the pontoon but haven’t sourced my third tube yet. I’m going to stick with u-shaped to avoid the cobbled together look. I thought I’d be happy with the 60hp but it’s pretty sluggish. I thought I’d be ok with a slow pontoon to hang out on and using the sea-doos for skiing and tubing but I’d rather sell the jet skis and have a toon that would do it all. Anyhow, looking forward to seeing your progress. Here’s my toon and the poor donor boat that I’ll steal the engine and outdrive from.

 

[WrenchMike]

An older thread by TurboM700 has some great info on the I/0 conversion (I especially like the engine pod design) I’m going for something similar but with a 3rd toon that will transition into the engine pod as smooth as I can make it.

 

[captmello]

An older thread by TurboM700 has some great info on the I/0 conversion (I especially like the engine pod design) I’m going for something similar but with a 3rd toon that will transition into the engine pod as smooth as I can make it.

feel free to start your own thread, we would enjoy watching your project progress as well. the water line on your pontoon concerns me, it looks like the rear is sitting way low, especially when your planning to add 1000lbs to the rear of the boat.

I added a third tube a few years back, but kept my same motor. just added a shorter tube ahead of my existing motor pod. I'm very pleased with the results.

 

[ahicks]

Yup, I was looking at that water line as well. Not good....
Hate to be Debby Downer, but in my experience, since the recent popularity of the 4 stroke outboards, the number of IO installs, especially those installed in pontoon boats, have taken a huge nose dive. They're heavy, and can be very difficult to work on once installed - even when it comes to routine maintenance. From a performance perspective, it takes a LOT of power to offset that weight on a pontoon boat. Even at that, if you look at the very scary REALLY fast 'toons, they are all outboard.

My point is, prior to spending a lot of time and money for an IO conversion, you might want to check into a (used?) 4 stroke outboard install to see if the IO is still making a lot of sense. 3rd tube plan, under that pontoon, is likely a pretty solid plan outboard or IO. My thought anyway, FWIW.

 

[WrenchMike]

Thanks ahicks and captmellow for the insight, I’m gonnna need a lot as this project progresses. I already wish I held out for a pontoon with larger round tubes. I should tell you I’m new to boats and all that is involved with them. This project is definitely in the crawl phase and I’m still considering every option. I bought the Lowe this spring and the water line has concerned me since day one. I pulled the plugs the day I got it home and it drained for quite a while. I don’t even want to guess how full it was. My guess is the foam filled tubes are waterlogged as well. Removing that heavy foam and finding the leak(s) will be project #1. Can water get in the top of these tubes where the top slides in? It sat next to a pole barn with no gutters, so the water poured directly on the deck for several years. I’m going with the i/o basically out of ignorance and a little “can I make this work”. I know nothing about 2-strokes and even less about outboards. A Chevy 350 is familiar for me (the outdrive and marine components will be a new adventure). The plan I have is to find the larger size 3rd toon and mount it several inches lower than the outer tubes. I will build a fairly wide engine pod to help with buoyancy and allow the engine to sit as low as possible (Keeping prop height in mind) and transition it into the center tube as smoothly as I can. I’m a little concerned as to how much space will remain between the engine pod and outer tubes. I’m not sure how that will affect handling and ride quality. Will it be a noisy turbulent mess under there? I have considered rolling my underskinning to make it more tunnel-like but won’t worry about that for a while. I did spend a while looking for a good outboard in the 200hp range and anything I would be comfortable with was above my budget for this project. I picked up the running Cobalt 260 (~300hrs on the Hobbs) for $400 so hopefully I’ll have a reliable power plant for a few years before I rebuild it. I was looking for a project and this kind of fell into my lap. I love fabrication and have a good amount of tools and equipment available to me (I’m an aircraft mechanic by trade). There is small reservoir about a mile from my house that we love going to with friends on hot summer afternoons. Most of the time we are on a sandy beach soaking up the sun but it would be nice to go pull the kids around from time to time. I’ll start a new thread on the build as soon as I tear into it (and find an affordable 3rd tube). Thanks again!

 

[WrenchMike]

Thanks ahicks and captmellow for the insight, I’m gonnna need a lot as this project progresses. I already wish I held out for a pontoon with larger round tubes. I should tell you I’m new to boats and all that is involved with them. This project is definitely in the crawl phase and I’m still considering every option. I bought the Lowe this spring and the water line has concerned me since day one. I pulled the plugs the day I got it home and it drained for quite a while. I don’t even want to guess how full it was. My guess is the foam filled tubes are waterlogged as well. Removing that heavy foam and finding the leak(s) will be project #1. Can water get in the top of these tubes where the top slides in? It sat next to a pole barn with no gutters, so the water poured directly on the deck for several years. I’m going with the i/o basically out of ignorance and a little “can I make this work”. I know nothing about 2-strokes and even less about outboards. A Chevy 350 is familiar for me (the outdrive and marine components will be a new adventure). The plan I have is to find the larger size 3rd toon and mount it several inches lower than the outer tubes. I will build a fairly wide engine pod to help with buoyancy and allow the engine to sit as low as possible (Keeping prop height in mind) and transition it into the center tube as smoothly as I can. I’m a little concerned as to how much space will remain between the engine pod and outer tubes. I’m not sure how that will affect handling and ride quality. Will it be a noisy turbulent mess under there? I have considered rolling my underskinning to make it more tunnel-like but won’t worry about that for a while. I did spend a while looking for a good outboard in the 200hp range and anything I would be comfortable with was above my budget for this project. I picked up the running Cobalt 260 (~300hrs on the Hobbs) for $400 so hopefully I’ll have a reliable power plant for a few years before I rebuild it. I was looking for a project and this kind of fell into my lap. I love fabrication and have a good amount of tools and equipment available to me (I’m an aircraft mechanic by trade). There is small reservoir about a mile from my house that we love going to with friends on hot summer afternoons. Most of the time we are on a sandy beach soaking up the sun but it would be nice to go pull the kids around from time to time. I’ll start a new thread on the build as soon as I tear into it (and find an affordable 3rd tube). Thanks again!

 

[ahicks]

Wondering about the tube construction. Do they seal to the ply floor to form the top, or is there an alum. cap that forms the top? How hard would it be to get that foam out of there?

Will a new ply. deck be part of this project? With that deck removed, access to the cross members and such is pretty simple. It would allow you to install extra and/or much heavier cross members to support the weight of the new pod.

With a little aviation background myself, my bet is you have the patience to see this through. Easier to see where you are coming from for sure. I did a ground up restoration on a Piper TriPacer, some major work on a C182, and was encouraged by some locals to go for an A&P. Had a blast, bartering with those guys. I gave them a hand with some of their contract work (progressive annuals on commercial stuff) that involved removing inspection panels and packing wheel bearings on a plane that had been downed for a weekend, and they covered my work (on my own stuff) and showed me how to pull the necessary paperwork for my planes. Annuals on my stuff never cost me a dime! Plus, I made a bunch of new friends - hangar rats..... That was a few years back now. Lots of great memories. -Al

 

[WrenchMike]

Wondering about the tube construction. Do they seal to the ply floor to form the top, or is there an alum. cap that forms the top? How hard would it be to get that foam out of there?

Will a new ply. deck be part of this project? With that deck removed, access to the cross members and such is pretty simple. It would allow you to install extra and/or much heavier cross members to support the weight of the new pod.

With a little aviation background myself, my bet is you have the patience to see this through. Easier to see where you are coming from for sure. I did a ground up restoration on a Piper TriPacer, some major work on a C182, and was encouraged by some locals to go for an A&P. Had a blast, bartering with those guys. I gave them a hand with some of their contract work (progressive annuals on commercial stuff) that involved removing inspection panels and packing wheel bearings on a plane that had been downed for a weekend, and they covered my work (on my own stuff) and showed me how to pull the necessary paperwork for my planes. Annuals on my stuff never cost me a dime! Plus, I made a bunch of new friends - hangar rats..... That was a few years back now. Lots of great memories. -Al

The way I understand it is there is a channel of sorts that a flat piece if aluminum is slid in on the top of the tubes. My shop is drifted in so when I can get to it I’ll have a look to confirm (some idiot left the tractor inside the shop before the storm and now I have nothing to dig out with ). The deck will be replaced for sure so I’ll know more once the old deck is gone. If that flat piece won’t slide out I’ll probably cut access panels to remove the foam and then tig them back up. I’d definitely beef up the cross members and spread the load and stress as far throughout the hull as possible. My first plane was a pacer (22/20 conversion). Sold it when my son was born as I needed the money in those days, but I sure do miss it. I’d agree with anyone who would say this project is impractical and not the best choice financially for my desired end result but it will be a lot of small investments (time + $) that I can make as both become available. Us being fans of aviation means we are seasoned in impracticality right? Like my Pacer, half the fun will be in the build (time with my kids, life lessons for them and a sense of accomplishment and pride). I know this is a boat forum but here is my pacer back in 2006(ish).

 

[WrenchMike]

HogHeadSena I’m sorry for hijacking your thread. I’m new to forums but I’m sure that is frowned upon. I’ll try and move this over to a build thread for my project. Keep me posted on your progress!

 

[ahicks]

OK, quick side track- EAA's magazine, Feb. 2000 I think. Interviewed by a guy I revered at Oshkosh (Bud Davison). I had already read nearly every word he had written. When he walked up to me and asked if I had a minute, just a few minutes after tying the plane down after arriving, I thought I had done something wrong.... -Al

 

[WrenchMike]

OK, quick side track- EAA's magazine, Feb. 2000 I think. Interviewed by a guy I revered at Oshkosh (Bud Davison). I had already read nearly every word he had written. When he walked up to me and asked if I had a minute, just a few minutes after tying the plane down after arriving, I thought I had done something wrong.... -Al

That is pretty cool. I had a guy come up to me in a hurry after tying down once. I thought he was seeing if I (or the plane) was ok after the landing I’m sure he witnessed. He just wanted to talk about the plane. I always wanted to go to Oshkosh but never made it. Beautiful Pacer!

 

[ahicks]

Thank you! That was serial #180, one of the earliest Tri-Pacers. There were only a couple older that were still registered. God only knows what kind of shape they were in! -Al

 

[catman977]

WrenchMike Instead of worrying about the Toon leaks, which are hard to find and repair , unless your a good TIG welder, use a 4" hole saw on the top of the stern of each Toon and install a good bilge pump with auto/manual power. That way you'll always know your not hauling, Heavy water around. The Foam will dry eventually .

 

[catman977]

lol I worked on Planes too, F100 Super Saber. Vietnam

 

[WrenchMike]

WrenchMike Instead of worrying about the Toon leaks, which are hard to find and repair , unless your a good TIG welder, use a 4" hole saw on the top of the stern of each Toon and install a good bilge pump with auto/manual power. That way you'll always know your not hauling, Heavy water around. The Foam will dry eventually .

That’s a good idea! I have thought of borescoping the tubes to inspect the condition of the foam. If it doesn’t appear waterlogged (I don’t know what dry or waterlogged foam looks like but I’ll get it figured out) the bilge pumps would be perfect. The boat will never be on the water for more than a day so a slow leak wouldn’t be a big issue. I’m a decent tig welder at best, but a professional by no means. I’m willing to work on my tubes and structure but I know my limits. I’m hoping to find a salvage pontoon with u-shaped tubes. One tube to add to my project and one to practice welding the thin skin. Thank you for your service!