Course How To

Expandable Trailerable Pontoon Houseboat

by Gary Severn
(Venice Florida USA)

I designed a Trailerable Houseboat that expands out to 12 feet wide from 8 feet wide. It's basically 3 units, 2 outside units and one center unit.

From the open 12 foot position, the two outside units slide toward one another 2 feet inward on each side until the width becomes 8 feet wide. The pontoons are fastened to the outer units in a fixed position giving the pontoon boat a very stable ride at 12 feet.

The outside units can be moved inward or outward using my patented hydro/electric system. Four simple pins lock everything into position. This is all accomplished in the water prior to loading the boat back onto the trailer.

The overall length can vary from 24 feet to 40 feet. It has 3 foot collapsible side decks with handrails the full length of each side of the boat making the boat 15 or 18 feet wide. (One side can be up when docking on that side).

The top deck is also fitted with a collapsible safety railing system. A collapsible Bimini can easily be raised up on the top deck for sun protection.

The interior has almost everything attached to the outside units so they can freely move in and out without having to detach something to allow expanding.

Powered with two outboard motors (one inboard of each pontoon). The trailer is designed to allow the boat to expand out when using the boat as a Travel Trailer.

All this works similar to 'Expanders/Sliders' on RV Trailers and Motor Homes.

So, what do you think? Want to build one?? Know someone that would like to build it?

Let me know. Thanks for letting me share, Gary

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Reply - Answer
What a great post Gary, sounds like an interesting project. If you're able to send some pictures, I would upload them here, since a picture is worth a thousand words.

IAN - from

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Comments for Expandable Trailerable Pontoon Houseboat

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expandable houseboat and built in trailer
by: Andy

Here is a design for an expandable:

I would love to know if any of you have built one like this? As some have stated, keeping the pontoons from twisting is the real challenge.

Also, does anyone know of a trailer that is built in? Imagine a situation where I have a light weight pontoon houseboat. I put in at the top of the Mississippi river and motor to New Orleans. I then rent a truck and tow it north or to my next destination. Has anyone seen a concept where the trailer is part of the houseboat or can be disassembled and slung under or stowed in some way?

Need to talk to Gary Severn
by: Darrel Clegg

I am definitely want to do see or no how this expandable pontoons work love to speak with Gary if ever possible I'm in the midst of either buying one or making one I would appreciate the help very much thank you.


Great minds think alike.
by: Christina

We came up with this exact idea also, and I was researching weights and fell upon this page. Great minds think alike! Would love to see pictures of the final product!

Sliding pontoon houseboat
by: Anonymous

I am considering building an Aluminum version of what you have described. I was wondering if there are any issues with the two pontoons wanting to twist while in the water.

I came up with almost exactly the same ideas you had independently. It just sounds like the logical solution to having a substantial sized boat that you can trailer to the lake and avoid the overpriced dock slip fees!!

Building an expandable houseboat
by: roger

I to am in the process of building an expandable houseboat. Pontoons are plywood as is most everything else. The boat goes from 8 foot wide for trailering to 14 feet wide at launch.

The boat splits and slides apart and splits at the door at either end of the cabin. The cabin goes from 8 foot to 10 feet. The pontoons split apart by moving the frame apart on the trailer. This is done with 2 small 12 volt winches for 30 dollars each.

I first built a scale model of the boat to make sure everything works. Door frames hinge in to allow for the two foot close up. Two foot strip down entire length of boat are removed in 8 foot lengths. 2 foot by 8 foot sections are removed from outside are removed.

Winches pull trailer bed and boat back to 8 foot wide. Will take one hour to one and a half I am thinking for me by myself to assemble. I have started on the pontoons, 4 foot wide by 2 feet high by 32 feet long.

I had to stop as it is winter here in northern Ontario. My garage is 28 feet and my pontoons are 32 feet. Oh yeah I am on dial up internet, so I will try to keep you posted when the weather warms up in April. Will try to send pictures of model.


Expandable Houseboats - try Travelwave
by: Anonymous

Check out the Travelwave360 for the houseboat that has fold up pontoons. It's manufactured in the USA.

Pictures of Expandable Trailerable Houseboats
by: Anonymous

Pictures would be great.


Any more info about the Expandable Pontoon Houseboat?
by: Dominic

I was interested in more info regarding Gary Severn's article regarding his expandable pontoon houseboat.

His closing remark is to contact him with further interest. Would you have an email address for that author. Thanks,

Reply - Answer
Well Dominic, unfortunately I don't have any contact info for this expandable pontoon houseboat article.

Hopefully the author will come back to share more information about his design.

IAN from

How do we get more info about your designs?
by: Anonymous

Please post more information and pictures if possible, regarding your collapsible - expandable pontoon houseboat.

Patented mechanism for trailerable houseboats?
by: Ray

Gary; I am thrilled at the thought of camping on the water, and then going back to the ranch with my "towable" houseboat. It is the perfect cross over, RV/Marine, concept.

However, if you intend on manufacturing, selling,
buying, or just talking about it your going to give up a little more info..

1. Photos!
2. Price range.
4. Privacy. Can't contact you to place my order.

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