tips for adding a new center toon to a ponton

[crb478]

I recently won a new never mounted 26.5 inch diameter center pontoon with the motor well on ebay that I still have to go pick up. I plan to mount this to my 1997 Crestliner 24 foot pontoon that has 23 inch tubes.

Plans right now are to remove the engine and then the motor well slide the new center toon in place on the trailer and bolt it in place lining the front tubes up evenly. The new toon is 24'8" long total and has lifting strakes. It has a 2 pieces of channel welded to it length wise for attaching it so spacing is not a problem. The transom is also cut lower so the engine can sit lower in the water, remount the engine and see if I have any improvement. I live on a large lake and hope to get a smoother ride, allow a few more people to sit up front where the go anyway and maybe pick up a couple of mph when running from a storm. Boat has a 115 Yamaha 2 stroke and on smooth water with clean tunes can hit 30mph. Boat has submarined a few times when others have driven it in rough waves.
What type of bolts or fasteners would you use to fasten the toon with? Would using some rubber washer between the cross frames and the toon channel be a good idea? Anything I am not thinking about? 5150abf I know that you probably have more experience with making things work than anyone. Do you see any inherent problems with this? I got the center toon cheap, probably less than or about scrap value so I am not concerned about the money, but I realize that I am not a factory engineer or expert either. Thanks for any advise Carl

 

[figgyb]

Re: tips for adding a new center toon to a ponton

I'm no expert but might worry about about the size difference making you a little unstable?

 

[crb478]

Re: tips for adding a new center toon to a ponton

I am not really worried about the diameter difference. The center tube has lifting strakes so at speed most of the boat weight will probably be on it. If needed I can line up all of the bottoms evenly after I try it out the way it is. I have seen tritoons that had the center tube slightly lower, and ones that have all three even. I have also seen where all three tubes are even at the front and where the center one is slightly ahead of the others.

 

[Todd4]

Re: tips for adding a new center toon to a ponton

One thing that immediately caught my attention - your existing tubes are 24' long. Your new center tube is 24'8". Is the center of your deck cut out in the rear so the motor can tilt up? My center tube is sticks out 2' past the rear ends of my side tubes (there's no cut out in my deck) and all three of my tubes are even in the front.

I'd use stainless steel nuts and bolts to mount the tube and NOT use rubber washers between the tube supports and under deck frame rails. I've never seen that before (maybe just a cloth/plastic strip to separate the two metals). I'll bet your other tubes aren't rubber mounted, either.

You should gain more weight capacity and a better ride in rough water, but I don't think you'll get much (if any) gain in speed. JMHO

As for the larger center tube - manufacturers are doing that these days to increase lean in a turn to make the tune more responsive = no problem here. Will it all work together? Only time will tell.

I hope it works out for you and you achieve all your gains.

Todd

 

[crb478]

Re: tips for adding a new center toon to a ponton

Thanks for the reply, Yes the center section of the deck is is currently cut out and the extra 8 inches should let the motor tilt up better than it does now. Currently it will hit the rear hatch/sundeck lid if tilted all the way up Crestliner put in a metal prop to address this situation. I still have to go pick up the center toon but hopefully I have not overlooked any thing that will keep this from working.

 

[airdvr1227]

Re: tips for adding a new center toon to a ponton

I'd place a wager you will go slower than you did before with the same engine.

 

[crb478]

Re: tips for adding a new center toon to a ponton

It may, but if it will run faster in rough conditions that will be fine with me as the lake is rarely smooth anyway, and when a storm blows up everyone is going as fast as possible to get out of its way making the water rougher. I hardly ever run at 30mph anyway, can't afford the gas at that speed.

 

[Bamaman1]

Re: tips for adding a new center toon to a ponton

Have at it since you've already purchased the third toon.

FYI: Pontoonstuff.com can sell you the stainless screws to mount the toon cheaper than you can buy them locally. Home Depot and Lowes are stainless steel bolt bandits.

You might want to carefully document the performance, before and after. The third toon would probably cost you a couple of mph, but the strakes might give you a net 2 or 3 mph increase. Your project's outcome should be very interesting.

I would think your boat's going to lean into a turn instead of leaning outside a turn. It should also be more seaworthy.

 

[rickdb1boat]

Re: tips for adding a new center toon to a ponton

Here's a good write up of someone putting a 3rd toon on. It's a little more involved than yours would be, since he's adding a fuel tank in the log too, but it might help answer some questions..

3rd toon install

 

[crb478]

Re: tips for adding a new center toon to a ponton

Thanks for the link, I had missed that one. I think that mine will be less involved, or hope so. From the info and measurements I have it looks like I should be able to simply bolt up the pontoon in place and have a 8" set back. The new motor well should fit in the same spot the old one did.

 

[MaPaHa]

Re: tips for adding a new center toon to a ponton

About three years ago I added a third pontoon to my boat and it’s longer than the deck of the boat so the motor tilts up fine. One other thing I added was an aluminum skin underneath to keep the water from slapping the floor joist in rough water and giving the boat a surge (slow down) every time a rolling wave comes underneath. It’s tough to do with three toons because there’s not a lot of room to work, but I feel it was worth it. I bent mine on a sheetmetal break so the sides came down about 8 inches to the actual toons. (You wouldn’t have to bend the 90 angle if yours are “U” tubes). A 90 degree battery drill helped to drill the holes for the aluminum rivets. I started at the back so the water would flow over the joints.

As far as performance goes, here’s what mine did. I originally had just a regular pontoon boat with two 23 inch tubes, an older Johnson 140 HP motor mounted on a custom built heavy duty motor transom. About five years ago I installed a “pontoon water glide” and what a difference it made! I picked up speed, lift, handling and turning. It was like a new boat and the product did everything they said it would do; no question about it. A couple of years later I thought I would gamble on a third pontoon and try improving the overall performance so I replaced the water glide. I picked up some features that had nothing to do with performance because I had an inboard fuel tank installed inside it along with an in-floor storage bin for skies etc. I also built a 24 inch rear deck where my tanks used to be and put a rear swim ladder on the back of one of the toons and built a ski poll and support arms from the center toon. Overall, the functionality of the boat greatly improved with the additional room and features.

Performance wise the boat has much more floatation and rides well even in rough water. Like yours, mine is about 2 inches larger diameter than the outer toons and it came with lifting strakes. I have to go back five years to when it was just a twin tube and say it is an amazing change in lift, handling, turning and just floats better with a crowd than the plain twin tube. Speed wise I actually lost an mph or two from the pontoon water glide but is still much better than the twin tube. So my estimation is you will gain speed as in my case. Last year I went on to add lifting strakes to the other toons to match the center toon and it helped getting on plane and general maneuverability some, but no noticeable top end speed in clear water. It just rides better and probably helps cursing speed and fuel consumption with a crowd and/or rough water. Top speed with a metal top is around 30 mph right now.

I’ll add that I bought a four blade prop from Power Tech that they recommend on pontoon boats (different model than one for a bass boat). I had to have it re-pitched after adding the third toon. If you haven’t planned on a new prop yet then I would. Yours will probably over-rev.

There you have it: An older 140 HP (rated at the crankshaft) on a twin tube boat -> add pontoon water glide (the biggest bang for the buck) -> Replace water glide with third toon with strakes (more features, more $$ and more work) -> add strakes to outer toons (some improvement in take off and general handling).

Next on my wish list is to find a bass boat with a 150 HP (rated at the prop) that I can buy reasonable and swap motors and then re-sell it without too much loss. This should get me 15-20 HP to run a taller prop. I’m 3-4 mph short from the speed I like to ski.

Hope this helps, Its been an on-going project but I’m not in the market to spend 30-50K

 

[5150abf]

Re: tips for adding a new center toon to a ponton

Sorry, don't get on everyday anymore so I am a little late to the party.

You really need to just put it on the boat and see what it does, can't imagine it would do anything weird.

The 2 things that jumped out at me are the diameter difference and the transom, the center tube will act like a fulcrum and the boat may be more sensitive to wake, floppy side to side, since the center tube is lower in the water the up side is it should also bank in turns.

Don't recall which company does it but that was their answer to the banking pontoon was to make the center tube a larger diameter turning the outboard tubes into outriggers so to speak.

As long as you can get the transom line up you are good and make sure you are parallel to the other tubes, get that off and it will always pull one direction or the other.

I would get it lined up and bolt it in the front and rear then do the middle so you are sure it doesn't move and triple check before you start dropping bolts and you are bolting it yes, this is not a job for screws.

I think you will go a bit slower or best case the same speed, you are adding several hundred pounds to the boat and the extra drag of the tube but you have chines which should get it up out of the water a bit so I am calling a slight loss or the same speed wise.

Let us know how she runs or if you have any problems.

 

[arntarchie]

Re: tips for adding a new center toon to a ponton

I added mine 3 years ago best thing I ever did.I dont have strikes but I did gain 3mph with the same 115 and flotation was a huge plus (about 1500 LBS up front ) my big change is in handling. old logs are 24' and the motor pod set back was 12",the new log is 25' that pushed the motor out 24" from were it was and put 40gal of fuel and or 280lbs down in the log instead of up on the deck with that new leverage and better center of gravity she banks real nice in the terns.
Sadly my changes dident stop there with the motor 24" farther back and all that fuel back there I had to move the axles of my trailer back to get it to road again

 

[crb478]

Re: tips for adding a new center toon to a ponton

MaPaHa, Thanks for all the info, I am looking for similar results to yours. My boat is a prop rated 115 Yamaha and I have already considered that I may need a new prop as well as possibly a longer steering cable. I currently have a four bladed prop and love it, especially when backing. I am not gaining any storage, but if it will allow me to run faster in rough seas I will be fine loosing a few mph, but keeping up the speed would be great too.

 

[crb478]

Re: tips for adding a new center toon to a ponton

5150abf I understand about not checking in everyday, When I retired I suddenly was too busy to get on line much go figure. Right now I am just planning on putting it on with the fronts even and let the motor set back 8" from the other tubes. Does this sound like a good plan of attack to you? I will be sure it is centered, I will probably make some jigs to hold it the same distance from the other pontoons, and yes I plan to use stainless bolts. I of course hope for the best, but as I said before if I can run it faster in rough water I would much prefer that to being able to run 30mph on smooth water. When the waves get up I am usually only running 15-20 mph and have to back off to keep from swamping the boat when the big cabin cruisers and cigarette boats throw out 3-4 foot wakes.

I borrowed a pontoon trailer to make the trip tomorrow, but that has been put on hold. After repairing the lights and wiring, and greasing the bearings I found that the wheels are dry rotted on the sides. So much for that trailer. I have a regular boat trailer I may use and bolt some 2x4's in a v to support the center pontoon.

 

[crb478]

Re: tips for adding a new center toon to a ponton

I added mine 3 years ago best thing I ever did.I dont have strikes but I did gain 3mph with the same 115 and flotation was a huge plus (about 1500 LBS up front ) my big change is in handling. old logs are 24' and the motor pod set back was 12",the new log is 25' that pushed the motor out 24" from were it was and put 40gal of fuel and or 280lbs down in the log instead of up on the deck with that new leverage and better center of gravity she banks real nice in the terns.
Sadly my changes dident stop there with the motor 24" farther back and all that fuel back there I had to move the axles of my trailer back to get it to road again

I hope that I have similar results to yours. I am hopeful that the extra 8 inches of set back will help keep the motor in better water. I am not worried about trailering as I don't have a pontoon trailer and my boat stays in the water year round. I am mainly looking for stability and handling as well as increased floatation when anchored.

 

[WaterDR]

Re: tips for adding a new center toon to a ponton

With the strakes and larger size, I wonder if it might tend to flop back and forth. But agree with everyone else, this si sort of an experiment.

BTW, one thing that seems sort of funny to me, the Pontoon companies have really marketed A LOT of engineering into their toon designs with all sort of fancy names and ideas. Crap, I remember years ago when "U" shaped tubes was some sort of amazing breakthrough. With all the hype and engineering at the end of the day, a pontoon is nothing more than a deck with logs. I don;t think your results are gonna be that much reduced from from others have achieved.

 

[crb478]

Re: tips for adding a new center toon to a ponton

I will try the pontoon at the set depth first, according to the measurements I have gotten that should put the center log 1 3/4 inches lower than the outside two, so I think that there will always be some part of the outer pontoons in the water. If needed I can modify the top mounting bracket and make the bottoms of all the pontoons the same depth. I have less than the scrap metal value in this so I the money is minimal. I just need to dive 300 miles or so to pick it up.

 

[crb478]

Re: tips for adding a new center toon to a ponton

Well with a little prompting I thought I would update where I am now at with the center toon. I borrowed a friends single axle pontoon trailer and fabricated a cradle made up of 2x4's and u bolts and put it in the enter of the trailer. Basically it was just a center set of bunks that supported most of the length of pontoon. About 30 inches was hanging off of the back and maybe 24 inches was unsupported in the center.
We loaded the toon by hand and pushed it all the way forward and then I hooked it to the winch strap in front and strapped the back down using the trailer frame and the rounded area of the motor well. I then strapped the center of the toon with 3 additional straps. These 3 straps crosses the top bracket used to mount the toon to the floor. In retrospect I should have used duct tape to cover the edges because on West Virginia's roads I broke all 3 straps at one time or another. I would stop tie them back together and then tighten them back down. The winch strap and strap on the motor well never had any problems, but the other three were all ruined. I believe the trailer spent more time in the air than on the ground in W Virginia! I drove about 385 miles each way and it took me about 12 hours to get back home, just stopping for gas. It only took about 30 minutes to get the tune loaded and to get back on the road.
Now that it is home I am waiting on another friends trailer to be free so I can pull my pontoon out and get the process started. His trailer will fit my 8 1/2 foot boat, the other trailer was welded at 8 foot.
Right now my plan is to center some 2 in aluminum angle under my boat where the new toon will mount. bolt it in place and then push/jack the new toon up to it. Make sure it is still centered and then drill holes and drop in 3/8 inch bolts with nylock nuts and washers. These have been ordered. Will update as soon as I have more.

 

[crb478]

Re: tips for adding a new center toon to a ponton

I now have the 3rd pontoon mounted and on the boat and the boat back in the water. First off I would like to state that this was a lot of work, so if you are considering doing this don't take it lightly.

I started this by putting my pontoon on a friends trailer and then took several measurements to make sure that the center pontoon would fit without raising the boat. It would but not by much. I got what I believed to be the center of my pontoon boat and marked that location front and back. Then I measured the distance between the center pontoons mounting flanges (16 1/2 inches I believe) and bolted 2 short pieces of 3 inch aluminum angle iron to the bottom of the boat towards the front. They were spaced about 8 1/8 inches from the center line. I thought that this would help me center the 3rd pontoon, but it turned out to be more trouble than it was worth and I had to remove one of the pieces of angle to get the center pontoon in place. The mounting flanges like to spring in so maybe it would have worked with a looser tolerance, but I really do not think it is needed. I removed my motor and the old motor well as well as about 6 feet of underskinning that was already on the back of the boat.

I pulled the center pontoon to the back of the boat and picked up the front end of it placing it on the rear cross bar of the trailer. I hooked the front winch to the front ring of the center pontoon and then winched it forward slightly. I picked up the back of the center pontoon with my tractor and slowly winched it forward constantly moving the tractor until it was in position. I used vise grips to hold the center pontoon near the center of the boat and then cut a 3/4 x 3/4 inch stick to the approximate length of the distance between the pontoons. I went back and forth several times tweaking the center pontoon side to side and cutting new centering sticks. I finally got the tolerance on both sides even and between a snug fit up to about an eighth inch of looseness. I realized early on that none of the pontoons ran exactly true nor are they perfectly round close, but not perfect.

On my boat I ended up with the center pontoon about 1 1/2 inches in front of the outside ones and the backs about even. It fit between the cross braces better at this location. I then started drilling 3/8 inch holes through the center pontoon mounting flange and cross braces of the pontoon. I had to use a right angle drill attachment with a stubby 1/8inch bit to start it and the switch to a step bit to get the 3/8 inch hole. It worked fine but I wore out the right angle attachment and it is a pain working between the 3 pontoons especially with it on a trailer. I put bolts with lock nuts on at every cross brace and doubled them up when I got to the flange that started the motor well.

I cut down and reinstalled the back 6 foot or so of underskinning that I had and remounted the motor after drilling the holes in the center pontoon motor well. I initially installed it in the lowest hole, but ended up raising it two holes as it was running to deep.

With the boat in the water the rear of the boat now sits 2 to 2 1/2 inches higher than before and the front is probably sitting 4 inches higher. Testing the boat out with somewhat dirty outside pontoons the boat rides much better and dryer. I need to clean the pontoons for a better evaluation but with clean pontoons on the old pontoon I could hit 31 gps mph on smooth water. Today with the Tritoon I only hit 25 gps mph on smooth water. That was with the old solas 4 bladed 13 pitch prop which was over revving at about 6200 rpm, and with my old spare prop which is a Turning point H2 1315 3 bladed prop that is 13 3/4 x 15 that is still slightly over revving at about 5700 rpm. My WOT range is 4500 - 5500. Right now I am running the Turning point but may try another solas 4 bladed 15 pitch prop for it in the future as the four bladed prop runs noticeably smoother and backs up better.

As far as cost well I figure I got a deal, I only paid $400.00 for the center pontoon, spent about $125.00 in gas to go get it, and spent about another $75.00 for bolts, lock washers, and flat washers of which I still have nearly 1/2. Throw in another $18.00 for a right angle drill attachment and who knows how much money in advil and bourbon to take care of the end of the day pain. It still needs some tweaking to optimize the set up but it is much improved except for speed. While it was on the trailer I also changed the water pump, cleaned both carbs with new kits, changed lower unit oil wired in new navigation lights and added new docking lights and housings for both, and a bunch of other routine items that needed to be done.

I also need to add underskinning to the rest of the boat since there is a wall of water coming off of the pontoons and soaking everything. Hopefully with the underskinning and by cleaning the pontoons I will be able to get about 3 or so mph back, but so far I consider it a success. The ride is much improved and I can actually go faster in rougher water than I could before. It also lets more people sit to the front before I have to make someone move to the back