50mph Pontoon

[BrianMc]

Compassboats, don't let me discourage you. Wasn't my intention,rather the opposite. I like the build even more when someone tells me my project isn't a good idea. In the middle of another one of those myself.

Whether you go with a double or triple build it can be done. I just wanted to give you a direction to start your planning,and an idea of the depth of the build.

A big tube double would be easier to reach 50 mph. Just wouldn't be the same animal in rough water. With enough strake it'll jump up on plane just fine. Would take some reinforcing,but that's part of the fun.

 

[Egret189]

Hey, guys.
I have been very very busy with school the past week or so. (I'm a full time business student). At any rate, you haven't discouraged me, so don't feel sorry. It is definitely for the better that someone with experience give me a reality check of what is possible and what is idiotic. In the mean time, I've just been watching craigslist and other websites very closely for a pontoon boat and engine to start my build. This will probably be the most time consuming part.
Here's another question I'd love to have you answer:
How difficult and expensive is it to add a transom to a tube? I have been presented the opportunity to purchase counter-rotating twins and was wondering how difficult it would be to build up a transom on both existing tubes and have twin power. They would each need to handle 150hp. What would be the best way to fab a transom? As for the center log, I will add it as the situation necessitates. If it becomes obvious that a center tube is necessary, I will take steps in that direction.
I rest assure that some of you are rolling your eyes at my suggesting of twin power (as if my previous fantasy was not outlandish enough). But what can I say? I pride myself in doing the extreme. Silver Eagle, Ercoa got it right. Buying someone else's engineering doesn't breed the same sort of satisfaction as building something ridiculous myself.

 

[BrianMc]

Now we're talking!

 

[BrianMc]

If it were mine I'd probably buy two large dia. 24'+ transom tubes,and build my own wide body frame and fence from scratch.

With time and budget a factor I'd start with a used 24'er,have a shop weld on some transoms and strakes,beef up the frame,and salvage the fence. Trouble with using an older 24' is their tubes are smaller dia. and the fences are kinda out dated.

With a twin double I'd also be thinking of ways to move weight forward.

 

[1983 ercoa 21']

Your thinking isn't far fetched my next one will be 30' already started rounding up parts or as Brian would say digging lol it will be a few years but I already have twin controls.lol . Keep us updated my guess would be between 500 -1000 depending on your fabricator and what he gets a hour.

 

[Egret189]

Brian,
Right. Most of the older 24s that I've seen just have chinsy tubes. They appear to be like 18 inches. I'm going to shop around until I can find one with larger-ish tubes. Also, I've seen some single pontoons for sale on CL in my area in the $200-$300 range that could work as center tubes. I've also been working to collect scrap aluminum to build with. It'll realistically be another few months before this project gets off the ground, but I'm making progress here and there. I haven't nailed down whether I want to go with twins or single and 20ft/24ft. I just want to be sure I've investigated all possibilities. The idea of a 24ft pontoon with 2 150s hanging off the back excites me more than it probably should.

 

[BrianMc]

A 25" x 24' tube toon will be harder to buy on a budget,but for a double that's what I'd be looking for.

On a triple the added weight of twins really wouldn't be an issue,but I still wouldn't use anything under 23" dia.

 

[MaPaHa]

My project over the last 5 years or so started as a 1983 Aloha with 23" tubes with a 40 HP. I've made too many changes to count but at this point I've added a third toon that has in-floor storage, a built in fuel tank, a 200 HP transom and lifting strakes. It's a "U" tube that's 25" deep so it hangs down slightly from the others. I had a old 140 Evinrude on the twin toon but I changed it to a '94 Johnson 150 Fast Strike with a 4 blade PT prop. The last time I had it out last summer I clocked it at 40 MPH GPS. The boat has aluminum under-skinning.

I had lifting strakes added to the old outer toons and had some trouble with leaks but should be fixed now but haven't had it on the water yet since the repairs were made. The bottom line on my trouble was there were some repair welds on the original toons at some of the tube joints that had been tight for a few years but when the strakes were installed over them they started leaking again. I would make sure to not put the strakes over repaired areas. Also, the welder was an experienced aluminum welder but not so much on pontoons. He also user a spool gun that he was not experienced in using. The other suggestion I would make is to turn the boat over for the welder so they don't have to do it overhead. If you put all that together you can have a nightmare on your hands with leaks like I did.

I would for sure stay above 20 feet because the builder rules shift from Coast Guard to ABYC standards plus you have more stability. I never liked the way the twin toon turned but I never had strakes on the twin toon. I did have a Pontoon Water Glide under it for a few years and I can't say enough good things about it. It was actually faster than the third toon. The down side to the water glide, and what I was looking for, was more flotation, storage and I thought the third toon would run faster. I got everything I was looking for but slightly slower with the third toon.

Bryan is right in that you'll have to get to 200 HP+ to see 50 MPH. From 150 HP and up is where the third too will be needed in my opinion. As you look around you'll see a line around 150 HP that leans towards tri-toons. In my experience, I would agree with it. I love the way my boat runs and glides on the water and wouldn't go back to a twin toon. We use it for cruising, camping on the lake, hauling stuff to islands, tubing, skiing and some fishing with a trolling motor to clamp on when I want it.

Mark

 

[Egret189]

Mark, thanks for the input! It's interesting that you built pretty much the same rig that I am trying to build even down to the exact motor. The motor that I end up using will pretty much be subject to whatever is available for a good price. I would like to go with a "big block" v6 to tap into the 200-250hp range, but I'm thinking that the 150-175s are a better overall value when weight, fuel burn and purchase price are brought into the equation. A lot remains to be seen at this point. A few questions for you: Can you PLEASE post pictures? Did you do any work to stiffen up the frame of the pontoon itself? Where did you source the material and design for you planing strakes? Are you running hydraulic or cable steering?

I ended up passing on those twin 150s, so the twin engine idea is out for now. I think I realized the fab costs of mounting two engines would exceed what I would consider to be a budget build. Back to the single engine realm for now. Or, at least until I graduate business school or start a business and have some extra money to throw around. (Evil laugh). Still on the hunt for my super cheap pontoon boat and engine. I will let you guys know when I start to put this thing together!

 

[Keepseln]

"When the student is ready the Master will appear"

You guys are awesome! I own a '89 24' Sun Tracker Party Barge and a 200 hp XP Evinrude motor. I've been planning the third toon upgrade for years now and it is great to see that I'm not crazy. Well not padded room crazy

To quote compassboats "A few questions for you: Can you PLEASE post pictures? Did you do any work to stiffen up the frame of the pontoon itself? Where did you source the material and design for you planing strakes? Are you running hydraulic or cable steering?"

My existing toons are 23", and I'm already planning on a two cable steering system and a third toon with built in engine pod. My questions; will a 25" center tube be the best version? If I find one with strakes, will just center strakes be enough or do I need to put strakes on the outer tubes? How much flotation can I expect from the third toon?

This forum has been a blessing and I thank you all for your input.

 

[BrianMc]

That's what I used. A 25" center with 23" outer tubes. I still had to add a spacer between the 25" and the frame to drop it below the outer tubes. The M-brackets on the 23's were taller than the brackets on the newer 25". I think it's worth a shot with strakes only on the center tube,especially with a 200. I'd drop the center tube at least 3" lower to help it ride on the center strakes. That'll help it turn,and raise more of the outer tubes out of the water. You can always add the outer strakes later,if it doesn't carry a load well enough.

 

[Keepseln]

Thanks for the advice. Here is another scenario;
I'm running a '73 evinrude 135 right now and hit a respectable 23 mph (lightly loaded). I wonder how the 135 would do with the center tube? The benefit of using the 135 is I don't have to change the steering system. So maybe do the center as a weekend project and save the 200 upgrade for the winter. Any thoughts?

 

[1983 ercoa 21']

I was running a crank rated 115 Johnson before and after the addition of the third toon before the third toon I was running a 15 pitch after adding the third toon I ran a 13 pitch I noticed some of the added benefit from the third toon but every one said I really wouldn't notice till I added a 150 hp or more well there is a 150 XP evinrude prop rated hanging on it now hope to splash it in this weekend. As to what order to do it in is all in how much time you have. I'd be interested to see if you got the same results as I did just by adding the third toon same motor.

 

[Egret189]

No Title

UPDATE:
My best friend has this 20ft 1964 Rivera Cruiser. Right now it has a 10hp with a antiquated cable steering system and stuff. I am thinking of possibly using this as my platform. It's pretty lightweight as it is already gutted. It's fairly stout as well. It has an adjustable height transom that obviously is not up to par for the HP I would throw at it, but it's sorta interesting. At first I wasn't really thinking this was the direction I wanted to go, but the more I look at it, the more I like the idea. The retro-styled fencing and stuff would look very neat all polished/painted up. My friend and I together equal a little over the weight of you average 150/175 outboard and with us standing on the farthest tip of the rear of the toons, the "rake" is hardly noticeable. I should also add that I can get it for a pretty fair price.
What do you guys think? Do you foresee any major obstacles going this route?

 

[1983 ercoa 21']

Mine was a 83 and had galvanized cross members which I replaced with aluminum.(added cost)

are them toons steel or aluminum?

you had asked in a earlier post if there was extra cross members added I added three extra at the back and two extra at the front.

 

[1983 ercoa 21']

The diameter of them toons look small here's what you my run into.
mine are next toons which are a smaller diameter and my center toon is a 25" round. I ended up with the center toon 8" deeper than the outer ones. Which causes a little rock from side to side when sitting still and someone walking around but the ride is great

 

[BrianMc]

To be honest, no way I'd hang a 150 on there,transom tube or not. And I'm a speed freak. Lol


Keepseln, that older 135 might only be 120 at the prop. I doubt it would push you up on plane with only center strakes. Adding outer strakes might get you on plane,but your not going to get much speed out of it. There is still a big advantage on ride just being on plane though.

 

[Keepseln]

BrianMc, thanks for you thoughts. I took at look at your build thread and DAAMM that's bada**. My current plan is to pick up the toon as soon as the $$$ is available and then worry about the 200xp upgrade. Even if I don't see any increase in speed the ability to ride comfy and out of the water is worth it.

 

[BrianMc]

I agree with the ride. Question is whether the 135 will plane out on just the center strakes. I think the 200 would,but you won't be up to potential and it'll take more speed to stay on plane. I'm running on roughly a 46" wide planing surface. Mine pops up really easy with a motor that puts out 165,and stays on plane down to 14 mph. You'll be at about 1/2 the planing surface. To give you food for thought......

 

[MaPaHa]

The center toon I added was built out of two new "U" tubes from a guy in southwest Missouri. It was built with a transom designed for 200 HP and was fitted with lifting strakes, a center storage cavity and an in-tube fuel tank. When I originally installed it, the outer toons did not have lifting strakes and it was powered with an old Evinrude 140 HP crank rated motor. It would plane out pretty good but not like it did when I added the outer strakes. When I rebuilt the boat a few years back I added extra cross members to the back because I knew I was going to do something for more power. My rear two cross members are 2" square aluminium tubing x 1/4" thick braced with a 2x2x1/4 angle aluminum for a total of 4" long x 2" tall each. The strakes I installed on the outer toons are from the same place I got the center toon and the best remember they are the same as the G3 boats. I'll send a PM on where I got them because I don't know if I can say it on the forum. The strakes themselves add strength to the outer toons.

As I said before, I had a nightmare when the strakes were added to the old toons. Be sure to flip the boat over for the welder and don't cover up any previous repair spots that have been welded on. I had to remove mine and have the old spots plated over and then re-installed. One of the big issues was the local welder used the wrong machine the first time (spool gun) and pretty much jacked it up when he blew holes in the pontoons behind the strakes.

Brian welded his on himself and can give you more advise on doing it right the first time and has been very helpful to me on getting mine fixed. I think He has the same strakes as I do. Again, I would make it easy on the welder and turn the boat over for them. You will get a better job.

When I put the 150 HP on, I built it with a "Bay" extension making it a XL shaft 25" motor. I install it on a manual 5" or 6" jack plate so I could mess with the motor height.

My steering is a tel-flex anti-feedback unit but it is hard to steer when I'm going mid 30's and higher. I'm going to install the hydraulic steering system I ask about in the thread on this site a few days back.

​Mark