About to start building a house boat from scratch!

A few years back I came across a pair of huge fiberglass pontoons that were in pretty bad shape but were difinitly worth fixing. The pontoons are 32' long 3' wide and 3' tall. I picked them up for $500 and I think that I got them for a steal of a deal after looking to buy pontoons to build a house boat and couldn't find anything close to being this big. Right now I'm doing all fiberglass work myself and after I finish the patch work and paint them with gel-co. The next step is for me to design a frame to marry the 2 pontoons to make a very solid structure to start build my house boat on. In my opinion fixing and patching/reinforcing the pontoons and the frame which will be made out of aluminum is the most important task in building this houseboat.

Eventhough I have a design in my head on how I would like this built
I would like your opinion on how you think I should design the frame to marry the 2 pontoons together, the more detail the better. You may think of something I have not. Keep in mind I would like the house boat to be about 40' long and anywhere from 16' to 20' wide after completion. I will be posting multiable pictures of the pontoons for you to fully understand and visualize what I'm working with. Any info would be considered and appreciated. I anticipate on sharing this boat building experience with you all as I build her and I'm glade that I found this forum to do so.

 

search on house boat... there are alot of entry hope u found experience of other who laready on the topic CHAO...

 

I suggest buying a set of GLEN-L houseboat plans. That might save you a lot of headaches, wasted materials and time. The plans should give you enough info to build a well designed and constructed houseboat on your 'toons.

https://www.boatdesigns.com/products.asp?dept=172

Please do post your progress!

 

Your 3' x 32' tubes will support 44,013 pounds (fresh water) each, with them being just awash (pi r squared x the tube length x cu. ft. of fresh water). This of course doesn't count their weight (subtract their weight from the total displacement). To have a reasonable safety margin, you'll want to have your full up, constructed weight, with full tanks and equipment around 1/3 to half of the total displacement of these 'glass tubes. This margin of safety will permit considerable "pounds per inch" of additional submersion.

Aluminum is a good material (if you use a proper grade) in the marine environment, but it doesn't bond well to 'glass. It's also difficult to bolt or screw to 'glass.

If it was me, I laminate large flanges on top of the tubes, which could receive through bolts. A typical ladder type frame could then be attached and more conventional structures built atop.

Weight will be your biggest enemy, so keep the construction light. Typical "platform framing" like used in houses, will be quite heavy. Metal studs would be a much better way to go, as you'll save huge amounts of weight and retain the strength. A composite structure would also be a wise choice, possibly using those laminated aluminum skin over foam panels, currently being put in car port roofs, as your walls (and roof). They're self supporting, rigid and moisture proof, plus very light weight.

I'd be concerned about very much cantilever in the ends of the boat (32' tubes, 40' boat). You can generate huge forces with just a small amount of cantilever, so work out the math and add beef were necessary.

The other main think to work out is the weights balance, so she'll float pretty much where you figure she will, when launched. You can easily have one end sinking lower then the other or one side (list), which isn't particularly comfortable or attractive. If your tubes have been compartmentalized, then you could "counter flood" to balance things out and get her on an even keel. This requires a fair amount of fore thought and planning, which most novice builders lack. So, calculate your building material weights and balance the boat out.

You could do yourself a big favor and run your drawings and calculations by a designer. For a small fee, you'll find out areas where you need substantial modifications, possible other trouble spots, questionable engineering, etc. It can save a lot of embarrassment on launching day, not to mention loads of materials, sweat and effort on your part, building something untested or calculated improperly. This would be especially true if you intend to motor the boat a bit, rather then leave her berthed as a park queen.

Check my gallery for a houseboat around the size of yours, called Belle.

 

To all who replied so far thanks for showing interest and for the info you have given me so far. I did do some calculations awhile back but I misplaced my notebook so I have to calculate again. Thanks par for the mathmatical formula, now I don't have to derive it again from scratch. I was thinking about making my pontoons bigger. When my dad built his 56' x 20' lifitte skiff a few years ago he pop the hull out of a 45' mold which was the largest hull avaliable he wanted his skiff bigger so he added 10' to it by cutting the hull in half and reconstructing another 10' piece in the same mold and joining them together with a few stainless steal plates in statigic places along with added stringers and fiberglassing everything in the general area again inside and out. I was thinking about doing the same thing but to a smaller scale to make my toons a little over 40'...........I will take pictures of my pontoons tomorrow and post them so all can see exactly what I'm working with.......this is fun already and I haven't even started working on this project again..........thanks again

 

The biggest question you should ask yourself is, will the laminate schedule used for the pontoons, be sufficient in supporting the amount of displacement you expect to burden the boat with.

 

here are some pics of the pontoons.................damn it says that my pic's are to many MB for this site.........what do i do?

 

If you have photo editing software you can resample the pics and then save them at a lower resolution. Most all packages will do this pretty easily. Then post them.
~martin