dividing pontoons into 4 per side, is this a terrible idea?

hey, guys. i've been reading through many multihull designs here, and all over the internet, and i want to build a portable plywood pontoon boat with 6-8 (36x12x12) pontoon sections that will arranged 3-4 per side inline with spacing somewhere between 3-12 inches between each pontoon. the pontoons will be rectangular, but with rounded corners, and only slightly rounded bottom. i know it will float, but i don't know how it will move considering the pontoon shape and the gaps between them.

i'm new to boats and building them, but i like making stuff, and the challenge of this project. i know you guys are the people to ask, you've been very helpful in me getting as far as i have in my design.

 

Having spaces between the segments is a no-no. If you do it that way the boat will have unreasonable drag, make a lot of turbulent waves and it may splash or spray a lot.

You can build in segments, presumably for ease of storage. If segments, then they should be carefully matched at the connections and have no space between the connections.

 

thanks, that's what i thought. the current design is more of a raft or floating dock, i guess. my ultimate goal, which may not be doable, is to make a roughly 12 x 7 modular platform boat that i can break down into about 40-50 cubic ft of space, the back of a hatchback or small wagon with seats folded down. the deck will break down to 6-8 interlocking panels or folding pairs of interlocking panels. i want each pontoon to be hollow, with a locking watertight top, so i can stack them inside each other.

would making the front (and possibly back) of each pontoon V shaped improve hydrodynamics much at all?

and would i be better off with more space between each section or less, in regards to turbulence?

 

if it makes any difference, it should weigh around 200lbs and trolling motor or outboard up to 5hp max. for propulsion.

 

An inflatable gives maximum compactness for storage/transport and light weight.
There are large inflatable pontoon boats, sounds like what you want.

You did say you want a 36ft boat to fit into a hatchback, right?

 

Couple of thoughts FWIW. Assembly/disassembly will take a considerable amount of time, so I wouldn't want to do it very often.
Many years ago, there was a company that made a cat sailboat design where all pieces fit inside the two hollow hulls. The 2 sealed covers were at the stern. There are also nestling kayak designs without the covers.

Raft type designs would appear to be the least efficient as far as propulsion energy required, better to go with pontoons unless you need a very short and wide raft. Inflatables would be the way to go as has been pointed out. If it has to be solid, maybe a telescopic construction, assuming the seals can be worked out, would cut assembly time...

Pon

 

i only want it to be about 12 ft or so. the 36 was inches in length of each pontoon segment.

one disadvantage to inflatables i've seen is cost. i want to build this whole thing for under $500 including a motor of some variety. I originally wanted an inflatable, then was drawn to the coroplast boats, then homemade pontoons and catamarans.

what i want to build is the eco power cat, but i don't have a trailer, towing vehicle for that weight, or the money to build it.

regarding the time to assemble/disassemble, i agree. the plan is for a weekender (possibly even camper on land), so one set-up/break down cycle over a weekend isn't bad. the whole idea of a modular design appeals to me enought that i am willing to invest the time in designing and operating it. there's something about having something do things or go places that they're not supposed to. you're not supposed to be able to put a pontoon boat in the back of a hatchback. like rooting for the underdog, you just wanna see it happen.

i'm just gonna lay it all out as well as i can, and i feel like that is with the pictures that are inspiring me. basically, i want all of these designs merged into one. in my head and on paper, it seems do-able. i wanted to use rows of rubbermaid roughneck 95qt storage containers for flotation locked into rails like the patent below, on a plywood/wood deck with a folding cabin on top much like the car-top camper, and with the over all aesthetic of the eco cat. i still want to do all of this, but i think i can make the hull sections out of coroplast over plywood ribs. if so, it will be lighter and even more flat-pack. the car-top camper is practically the same overall shape as cabin of the eco cat.

thanks for your replies. any thoughts and advice are greatly appreciated.

 

Under $500 including a motor and batteries is not really going to happen if you use new materials. A small open boat, ok, but not like you show here.
My question is are you just looking to get a boat as described, or interested in learning and building something, and particularly something different? You would need to understand how UV destroys lots of things so something like a tote will crack and fail after a short time outside,
and also how strong water pressure is to collapse anything not solid.

A small car can tow a boat on a trailer very easily if the boat is not heavy,
500 lbs jetskis are towed by small cars all the time.

One can find old trailered monohull boats for very cheap, even free,
for the really low budget this is the way to go.
Get one and modify it to be lightweight, as old solid fiberglass boats are very heavy.

My current jetboat project I bought for ~$500 and sold the motor for ~$300 and the outdrive for ~$400, so I started the project with $200 and a boat and trailer.

 

i want to build this as close to my idea as possible. of course i would like to learn in the process and apply that to make this something unique. well, as unique as it can be combining other people's designs and technology.

under $500 is going to be tough, i know, but i can go over. i don't want to buy a boat. i found a nice old 60's aluminum boat with trailer for $250 on craigslist. i know they're out there, but i have a Golf, a Jetta station wagon, and a Civic and amazingly NONE of them are even rated to tow anything.

if i use coroplast for hull skins, it's so cheap that even with UV degradation, replacing all hull surfaces might cost as little as $50.

i have freeship and blender installed, but i'm more familiar with graphics and video editing software than CAD, so i plan to build a couple of physical models to better illustrate my idea for myself and others.

 

can a moderator change this thread's title to "Folding camper boat (dividing pontoons into 4 per side, is this a terrible idea?)" please?

 

Modular/folding/nesting/etc.

I am also thinking about making a plywood boat that can be easily transported (and stored - I live in an apartment). Pontoons were an early idea for me, and I thought about 55 gallon (or smaller) poly drums (each one floats 441 lbs. minus drum weight, http://www.usplastic.com ), buoyancy tanks (a 2' by 3' by 12" floats 313 lbs.),nylon ratcheting straps, wood frames, etc. Not sure a trolling motor or small outboard would move it much, and the boat would not be that easy to store or transport (but fairly light and good capacity).

Then, for a while, I got into Ken Simpson plans (look him up at portable boats for some great ideas). Paul Elkins has coroplast folding boat plans that fold into a Honda CRX (the tiny hatchback), and he's got great ideas about everything. Lewis Boats has a cool nesting apartment jon boat. Not your pontoon boat, but at least check it out.

Personally, I've decided on a 15'4" by 4' jon boat that folds in half (heavy duty hinges at "transoms" 7' 8" in from bow and stern) to make a kind of enclosure/trailer top that will sit on a cheap Harbor Freight 4' by 4' trailer. I got the idea partly from an old 14' folding punt page (at Bateau's site, I believe), and partly from a folding Camper boat at Simpson's portable boats. Under 200 lbs. with 3/8" ply everywhere (except for transoms), and with no rocker at stern, a 40 lb. trolling motor or 3 h.p. outboard should move it along. Easily enough capacity for me, my wife, and my 2 young kids at 4" draft, and I either park it as a trailer or keep it inside the bed of my truck. Easy for you to tow with a small car.

 

correction

sorry, not Bateau's. It was Clark's at http://www.clarkcraft.com/cgi-local...d66b30995&type=item&categ=016&item=1039528499

also, there are some great tiny houseboat pages out there, including ones that used 18 wheeler inner tubes, etc.

 

If you want to be 'eco friendly', then I really suggest starting with an old fiberglass boat and modifying it, because otherwise they just end up in the landfill and don't decompose.
Aluminum boats can be recycled, and wood boats decompose, but fiberglass boats last 'forever', which is why they are so often free, it costs $50 to take them to the landfill here.

Using materials that won't last is also very non-eco-friendly as it just adds more to the waste stream.

I suggest you find one you can convert into a catamaran like the one shown,
chop it in 'half', etc, that sounds like a fun project.
Here is one in atlanta asking $400.

Picture this boat cut in half, now you have two pontoons..

Here found another one that looks better to hack on, this 10ft one is $150,
perhaps you can cut it up and make it so it bolts back together.



BTW, here is a 10ft inflatable boat for $129 so these chinese inflatables are not expensive.

http://rubberboats.com/product/new-inflatable-boat-excursion-5.html

 

Dachs; Coroplast??? That is the stuff that election campaign signs are made of. The Coroplast that I know is what it says it is: corrugated plastic as opposed to corrugated kraft paper. It has little impact resistance, little structural strength when compared to conventional materials like plywood.

Please tell me things that I do not know about this material. Yes it is water proof, more or less. Seems to me that the cells could easily become mini water tanks. Not a pleasing prospect.

I suspect that a more feasible, cheap, and probably safer structure could be made as skin on frame with nylon or polyester but not with plastic cardboard for a skin. SOF would be lighter too. I'd opt for ply not SOF.

A light boat of the size that you describe will be no problem for the VW or the Honda Civic. I pull a lightweight 16 foot boat behind my Honda Element with no trouble at all on extended trips to wherever my fancy leads. The fuel mileage diminishes by only about one mile per gallon. Way back when I was a crazy kid, I trailered a 14 foot outboard runabout all over Florida with my motorcycle.

Build a lightweight boat of conventional material and design, get a small trailer and save a ton of grief, money, and disappointment while upgrading the convenience quotient by a large margin.