Help with a pontoon type boat

[mac4x4ram]

I am concidering building a pontoon style boat using pvc pipe as the pontoons. I would like to use four 12 ft. by 8 in. pipe as the pontoons. I was thinking about 3.5-4 ft. wide. From there I am not sure. Any suggestions?

[PAR]

Have a good PFD around your neck when you launch . . .

[mac4x4ram]

Originally Posted by PAR

Have a good PFD around your neck when you launch . . .

Is my idea that bad? My calculations come up with supporting a little over a half ton. I am just going to use it as a creek boat possibly powered by a trolling motor. If it is a bad idea then I will just clear my mind of it. Please let me know before I waste my time.

[kapnD]

have looked into the pvc pipe pontoon idea, best I found was corrugated black drain pipe. I found it locally in up to 24" dia, and its very light, at least in comparison to sch 40 pvc. It is thin and resilient, and the corrugations give it great compressive strength. Lighter grades of pvc are available, but not very strong.
My quest is to build a disposable Huck Finn style raft with a small cabin or tent and power it with a 10hp Honda outboard for a summer journey down the Mississippi river.
The craft would be 20' long (one section of pipe)and have 2 or 3 24" pontoons as necessary to achieve flotation
The 1/2" plywood deck would be built on poles lashed to the pontoons(may be necessary to reinforce the pontoons at these points with plywood discs inside, we're open to ideas here!)
The ends of the pontoons can be pinched and sewn together over a 2x4 with the aid of a drum of hot water to make it flexible, then sealed with spray can foam.

[PAR]

I hear about this sort of thing several times a year, mostly during the early spring. Seems the bugs are out early this year.

Having just used some corrugated plastic pipe for a septic repair in one of my rentals houses this week, I can say without question the idea is foolish and most likely dangerous. They have no strength, are as flimsy as a noodle and being PVC can't be glued, other then welding. Filled with foam they may have some strength, but that would be a very large amount of foam, which ain't cheap and attachment is still a problem. Lashing would be the only cheap way to attach anything. The corrugations would serve no good in hull efficiency, a log would be a better choice flow wise, not to mention attachment of parts would be much easier.

The whole idea behind tube construction in pontoon boats is the self supporting tube. If the tube is in need of major reinforcement then you may as well build a hull or set of hulls. A barge hull is quite simple to build, dory hulls with a platform between would serve well also.

Building a long box with a pointy end in the front is the easiest way to go. Build two if you want a pontoon thingie, but the stowage and seaworthiness of a real hull offsets the extra material/engineering needs. There are lots of plans available for this type of craft BUY A SET . . . they're as cheap as the folks trying to do this sort of thing or go a head and reinvent the wheel if you think ya'll are the first to come up with this ridiculousness each year.

[kapnD]

Par, Come on man, take a walk on the wild side! I see that you do boat restorations, possibly this is the reason you're not willing to look outside the envelope? You only wish to deal with the old, tried and true, but where's the pioneer spirit in that? This modern world is bursting with new products, and forums like this can bring them together with ideas...

Look at www.etown.edu/physics&engineering. Click on projects.

[Sketch]

Not that PVC rafts/boats are really my cup of tea, but PVC is pretty strong stuff. Driving a backhoe over a length of sch 40 4" pipe only mildly deforms it - you'd need to mash it up with the bucket to actually break the wall. With regards to the end, why bother with foam and hot water, when you can clean/prime and solvent weld caps on? Even with a PFD I'd steer clear of rapids though...

[Kevin Lester]

As pointed out by Sketch pvc can be glued using 'PVC weld' glue. I've done a lot of plumbing using 100 mm (4") PVC pipes. I've sometimes made a mistake and glued the fitting on at the wrong angle or something and it's impossible to get it off again without destroying the pipe and the fitting. In South Africa we have different colour PVC pipes for plumbing, the white pipes have been formulated for UV resistance and they seem to last many years of sunshine. The PVC is also very tough, I've seen the pipes being abused but I've never seen one crack. I think that it could work for a limited use pontoon.

[Kevin Lester]

If you think the idea of PVC boats is bizarre, how do you like this; once a year the Concrete Society of South Africa holds it's 'Concrete canoe race' (also held in other parts of the world). There are very few rules but the hull must be constructed using portland cement. We take biddim cloth and immerse it in a paste of water and portland cement. The cloth is draped over our mould and allowed to cure. The hull thickness is around 2 to 3 mm (1/8") Strength depends largely on the design of the boat, a deck is essential to prevent the boat from collapsing when the crew climb in. Usually the boat will only last the race day but the event is huge fun for the families of employers that take part. It's surprising the punishment that the 'concrete canoes' can take.

[kapnD]

found these cool pontoons at www.plasticpontoons.com
The 24" model looks to have pretty fair lines.
I was especially intrigued by the modular feature.