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  #1  
Old 06-15-2012, 10:49 PM
rock rock is offline
 
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newb - building a houseboat on a pontoon boat?

I have decided to convert my pontoon to a houseboat. I am sure I'm not the first to have this idea and thought maybe I might get a little insight. There is nothing better than wisdom of those that have been there. Thanks
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  #2  
Old 06-15-2012, 10:58 PM
Mr Efficiency Mr Efficiency is offline
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I 'spose it depends how far/fast you want to go, can't imagine the average pontoon is going to have an underwater shape that is halfways satisfactory.
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Old 06-15-2012, 11:49 PM
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philSweet philSweet is offline
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Don't do it. Unless it's a monster pontoon boat, it won't handle the weight. It will roll over and sink when loaded down. They are designed to carry a certain load. It is printed on the makers plate. You can't build the house in the allowed weight. A pontoon hull is not a very versatile hull. It must be operated in a narrow range of displacements. You'd have better chances with nearly anything other than a pontoon. I've seen a Carolina Skiff converted to a houseboat that survived several hurricanes to everyone's amazement. It was at anchor. If it had been in a slip it would surely have sunk.

You need to figure out what every piece will weigh and and calculate the weight and center of gravity of the final product. There are no shortcuts for this. It is tedious, but it must be done.

for $500 you can buy a decent old sailboat and move onto it tomorrow. Just bring some rags and a gallon of bleach.
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  #4  
Old 06-16-2012, 12:38 AM
SamSam SamSam is offline
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People do it all the time.

Pontoon to Houseboat Conversion
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Old 06-16-2012, 02:07 PM
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philSweet philSweet is offline
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Well, that isn't what I call a house boat. It is a shanty boat. The thing behind it is a houseboat and weighs about 20,000 pounds. It's an old Gibson that used to belong to the company I worked for down there. The Redfish IIRC.

That isn't a pontoon boat either, its a motor catamaran. That is usually a bit better than a pontoon.

It still looks about at it's rated load just sitting there (A friend owned a Landau. Nice boats.)

better to just buy a big tent and use that on it.

I think Busman did a good job of explaining the limitations of his build so I won't go there.

A round pontoon has a higher deck than the Landau boats. Once you get past half submersion at any corner, things can begin to go badly very fast. Cat hulls arn't nearly so squirrelly as pontoons. You tend to adjust your behavior when the floor gets wet. On a pontoon, the roof will likely get wet when the floor gets wet.
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Old 06-16-2012, 02:46 PM
rock rock is offline
 
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Thanks for the replies. Appreciate the input. What I have is a 28' Party Hut with a 90 Merc. I also have a 14' slide in camper that is like new other than some ceiling damage. We used to have a blast in our motor home so we figured a motor home on water could be fun. The plan is to strip pontoon and camper then build a small cabin on the pontoon utilizing what I have. I understand the weight concerns and that is the main reason I am here. Safety is always my main concern. I have no idea how to determine what this current set-up will hold safely. The boat has 2 pontoons 28' long, 21" diameter and one pontoon 16' long, 21" diameter.
I have a performance boat background so this will be new to me. I have a good understanding of both construction and boats. I own a cabinet shop, machine shop, and metal fab shop. I will have room in the boat shop to do the project. Again I appreciate the input and will soak up all the info offered as I have no sperience in this particular field.
I am hoping to build an 8' x 16' with 80" sidewall cabin that will sit 3 1/2' from stern and leave 8 1/2' in front. Ideally I would like to use 1/2" frp. We manufacture cabinets for the mobile service industry and the company that makes the boxes for the trucks can supply me with panels 8' x 16' with a smooth, nearly seamless gelcoat finish. The boat has a structure supporting a roof now that I will keep using the panels for closure only. The other option is to build it like a Class C coach with a 2 x 2 wood frame with possibly corrugated plastic panels. I know this will not look like it came from a factory but I don't want it to look like it came out of my garage even though it will be coming out of my garage.
Just how goofy am I?

Rock
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  #7  
Old 06-16-2012, 02:55 PM
SamSam SamSam is offline
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Yes, but it's not like the OP has offered any clue as to what sort or size of pontoons he has or any indication of what he considers a houseboat, so I figure a blanket statement of "Don't do it, it will roll over and sink" isn't quite right. Busman considers his a houseboat and he also considers it a great success, having owned it for 10 years and having lived on it for months at a time. There's manufacturers of pontoon houseboats...
http://www.nivimfg.com/house8x26.html

GlenL offers plans for their Huck Finn pontoon houseboats.

Quote:
The HUCK FINN CABIN PLANS come in three sizes and are specifically designed for use with our Huck Finn and Super Huck pontoons. The construction methods used in these cabin plans assure you of the lightest weight cabin consistent with strength and simplicity of building. The 8' CABIN can be used on any version from 20' on up. The 12' CABIN can be used on any model from 24' on up. The spacious 16' CABIN can be used on the 28' on up.

Whichever cabin plan you select, you'll get a comfortable cabin arrangement which offers full headroom up to 6'-5" plus lots of light and ventilation. Each cabin plan features a full 3' roof overhang at the front as well as a 4' "porch" both front and rear as a minimum. And on Super Huck versions built to 10' beam, you have a 12" deck on each side. Every arrangement has a control console and facilities for a galley as well.
I wouldn't particularly consider them houseboats either, but it's a subjective term. I would rather stay on Busman's yellow thing than be all squeezed in a small, uncomfortable sailboat.

I've suggested to my wife that we take a tent on our pontoon and just screw it to the deck for a week or two. It would be fine with me but she wouldn't ever be seen on something like that. I think I'll just do it anyway, she can stay home if she wants.
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Old 06-16-2012, 03:55 PM
SamSam SamSam is offline
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We used to have a local source for those semi trailer side panels, 1/4 to 1//2" ply with smooth glass both sides. They were pretty heavy though.

They make an excellent fiberglass flatwork table. I made a real lightweight 8 x 8' panel on that stuff years ago. I made a light wood frame of 3/4 x 1 and 1 1/2" pine like a Japanese paper wall. I filled in the spaces with 3/4" polyurethane foil faced foam insulation from Home Depot. On the flat table (with a cover of polyethylene plastic stretched smooth) I put 1 layer of 1 1/2 oz mat, wet it all out with polyester resin and rolled out the bubbles, put on the frame/foam, put another mat on top and wet it all out, rolled out the bubbles, covered it with polyethylene and vacumm bagged it with an old refrigerator compressor as a vacuum pump. It's very lightweight. Not too strong but much much better than canvas etc., no flapping around. I only have it supported on the edges and its been a carport wall for 20 years with no problems, more intermittent support would help a bunch. A layer of cloth added both sides would add a bunch of strength and not add much weight. One other trick to what I did was every 6-8" or so I poked a 6" strand of fiberglass roving through the foam. That left a solid pillar between the fiberglass mats to resist compression while the extra roving on each side spread out and tied them together to resist peeling. Regular styrofoam would work with epoxy, I would think the blue or pink 2" stuff would be real strong and lightweight. Kind of like an SIP- structurally insulated panel.

I seem to remember elsewhere on this forum someone telling about laminating foam and aluminum sheeting to make lightweight wall panels.
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  #9  
Old 06-16-2012, 04:19 PM
WestVanHan WestVanHan is offline
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Rock..listen to Phil.

Few years ago in my area a guy did what you plan.
A friend was walking by,thought it looked heavy and before he could say anything the guy snarled out " I don't even wanna hear your f'in opinion-I've heard it before".

Month later I was in the area with my friend,he wanted to show me the disaster waiting to happen,and it was dragged up on the river bank,obviously been sunk and flipped. Never heard anything on the news about a drowning,so must have been lucky.

A year of work and $$$$ down the drain,probably in about 20 seconds.
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  #10  
Old 06-16-2012, 06:36 PM
SamSam SamSam is offline
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Quote:
Originally Posted by Jeremy Harris View Post
If you want the relatively low maintenance of an aluminium exterior, then you could look at using an alloy/foam/ply sandwich. I built a big box trailer like this a few years ago, using panels I made up myself and it ended up pretty light. I just bonded 2" foam sheets to alloy sheets, using polyurethane adhesive, then bonded ply sheets to the other side of the foam. The resulting sheets were light and very stiff, so I didn't need as much framing. I built the framing into the sheets at the edges, so it was pretty easy to construct the whole superstructure.

Jeremy
Quote:
Originally Posted by SamSam View Post
Are there different kinds of polyurethane, like different kinds of glue? What kind did you use? How did you go about making the panels? Did you have to clamp or apply pressure?
Quote:
Originally Posted by Jeremy Harris View Post
I built panels that were 8' x 4', with built in framing that was the same thickness as the foam, 2" but only an inch wide, for lightness. The glue I used was ordinary polyurethane construction glue, the light brown treacly stuff that cures by absorbing water from the atmosphere, a bit like Balcotan (but cheaper!).

I found that to keep the alloy sheets flat I needed to build the panels by laying the alloy sheet on the workshop floor (on top of some ply sheets to avoid scratches). I just roughed the alloy sheet up with coarse abrasive, smeared the glue over it, then laid the foam sheet and wood framing on. I used a few bricks to weigh the sheet down whilst the glue cured. As soon as it had, I glued and pinned (to the framing) the inner plywood skin to the foam. I used a few bricks on it to keep it flat.

The one important lesson I learned was to mark where the timber internal frame members were on the skins, so that I could find them later. I made the panels with an overlap on the outer alloy skin, and when I bonded the panels together (using Sikaflex polyurethane sealant/adhesive) I made sure that the lapped joint was well-bonded. If I'd thought about it, I'd have used a joggling tool to created the lapped joint in the alloy skin more neatly, but it worked OK without this, as the outer skin was thin, just 18g.

Despite the thin skin, the finished panels were very stiff and solid. I'm reasonably sure I didn't need as much internal framing as I used, but it was better to be safe than sorry.

Jeremy
Houseboat design...

This here doesn't look like a good thing...

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  #11  
Old 06-16-2012, 08:44 PM
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PAR PAR is offline
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The bottom line Rock is the pontoons and the rest of the boat need to be sized appropriately or ugly things can happen. The average pontoon boat is built very lightly and doesn't hold much up, by way or superstructure or weight. The pontoons are sized properly for this loading situation. If you over load the pontoons, you'll have major concerns to address. You can add a third or even a forth pontoon to address the weight issue, but now you're going to be into more effort and money, volumetric and hydrodynamic considerations aside.
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Old 06-16-2012, 10:02 PM
SamSam SamSam is offline
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Roughly figuring 63' of 21" pontoon submerged halfway comes to 4500# of displacement. That's what you've got to work with as far as the total weight of everything, boat, people, supplies, engine, fuel, beer, pets, food, toys, etc.

That's taking 3' off the pointy end of each pontoon and figuring fresh water at 60# a cubic foot. I have no problem with others rechecking my figures, in fact I feel better if they are so go ahead and re-cipher them.

Pontoons are not a good starting point to begin with, and 21" ones are small, but it's what you have, so you go from there. 4500# submerges your pontoons halfway. That's the perimeter of what sort of accommodations you can make. Some people make do living in a cardboard box, some people need marble pillars supporting their entryway.
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Old 06-17-2012, 12:58 AM
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PAR PAR is offline
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I got 151.593 cubic feet of volume for a 63' section of 21" pontoon. Times 62.4 pounds for fresh water equals 4,729.7 pounds half immersed. Considering the size of the proposed houseboat, this isn't much to work around, without some serious efforts to keep it light, such as composite walls and roof and light, spartan furnishings. There's a reason they build these things from aluminum Rock. 1/2" GRP panels will be ridiculously heavy and not a reasonable consideration for this project, given this volume to work with.
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Old 06-17-2012, 02:29 AM
SamSam SamSam is offline
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That's right, I was thinking 60 & 62 for the water weights instead of 62 & 64. So Rock, how much does the pontoon boat weigh?
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Old 06-17-2012, 06:26 AM
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Yep, that would be the first thing I would do, weigh the boat/trailer combo, then launch the boat and reweigh, just the trailer. Some simple math and you know what you have. I think you'll find you don't have much margin for adding stuff, after you count the engine, tank(s), steering, controls, crew and usual supplies and other equipment.

62.4 for fresh and 64.1 for salt Sam.
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