Float for houseboat

[Johnny5]

Hi all
I'm not sure if this is the right place to post but I'm hoping someone can help
We currently have a small cabin cruiser on the river and to be honest we mostly use our dinghy for short river trips so the boat is no more than a floating caravan
This is just a plan in our minds at the moment but we are thinking of selling the boat and building a pontoon houseboat a few others have done this along the river
I can't find much information online about the floats etc to make the base we are not talking to big maybe 10ft wide by about 25ft long ?
I was thinking about getting a couple of long steel airtight boxes made and building a frame across to support the floor etc
Any advice or a link to information would be helpful
Also advice on stability at this size ?

 

[benchmark]

There is a program series on NationalGeographic channel called ‘floating homes’ , it’s full of build inspirations from cheap build to floating mansions. You can see the episodes on the internet if you do a google search. Personally I won’t bother risking an attempt to make floating base without any hydroengineering experience, I would buy a decommissioned barge, ferry or boat that is already professionally designed to properly float in a balanced fashion, then I will build my own superstructure on that base.

 

[savageseadog]

Most I've seen appear to be reinforced concrete

 

[Plum]

Hi all
I'm not sure if this is the right place to post but I'm hoping someone can help
We currently have a small cabin cruiser on the river and to be honest we mostly use our dinghy for short river trips so the boat is no more than a floating caravan
This is just a plan in our minds at the moment but we are thinking of selling the boat and building a pontoon houseboat a few others have done this along the river
I can't find much information online about the floats etc to make the base we are not talking to big maybe 10ft wide by about 25ft long ?
I was thinking about getting a couple of long steel airtight boxes made and building a frame across to support the floor etc
Any advice or a link to information would be helpful
Also advice on stability at this size ?

I was going to do something like that a few years ago but never went through with it. However, I was going to buy an old "project boat" 9m Catalac Catamaran which gives you a very large "platform" with a lot of instant accommodation, then build an additional structure with standing headroom over the cockpit.

www.solocoastalsailing.co.uk

 

[prv]

Personally I won’t bother risking an attempt to make floating base without any hydroengineering experience, I would buy a decommissioned barge, ferry or boat that is already professionally designed to properly float in a balanced fashion, then I will build my own superstructure on that base.

Thing is, if you build a completely new superstructure, and make changes like removing engines and other machinery, you'll be completely changing the weights and balance of the boat anyway, and the professional engineering on that subject that went into the original design becomes largely irrelevant. It may no longer "float in a balanced fashion" when you build a big shed on the afterdeck, put a 2000l water tank in the bow, and install a 110cm cast-iron kitchen range on the port side.

Depending on what's available an existing hull might be a quick and cheap way to get a lot of structure to start from, but if it doesn't need to move efficiently through the water or survive offshore conditions, and you're going to completely throw the designer's weight-and-balance calculations out of the window with your rebuild, then I don't think the original naval architecture is of that much value to you.

Actual pontoon parts seem like they might not be a bad starting point for a stationary houseboat?

Alternatively, your 10' x 25' sounds a lot like one of those ugly "pontoon boats" used on American lakes - worth looking at one of those for inspiration (or even a donor boat if you happen to find one this side of the pond!). I believe their floats are made from sheet aluminium welded into tubes, like extra-long oil drums, then they use lots of aluminium box-section to form the deck frame and other structure. Then they add a shuttering-ply deck which is often completely untreated on the underneath and covered in synthetic carpet on top, and tends to rot out after a few years.

Finally (and at a price, I'm sure!) you could have a look at https://www.marinaboats.co.uk/ . There's a guy living in one, full-time as far as I know, in Shamrock Quay marina in Southampton.

Pete

 

[fisherman]

https://www.findafishingboat.com/multi-float-modular-pontoons-available-for-sale/ad-89571

https://www.findafishingboat.com/aqua-dock-modular-pontoons/ad-89687

or try Woods of Crediton

 

[NormanS]

The Scottish salmon farming industry has recently changed from using mainly rectangular flotation chambers, to circular tubular cages. The rectangular, polystyrene covered in a plastic skin, are/were readily available.

 

[Tranona]

Finally (and at a price, I'm sure!) you could have a look at https://www.marinaboats.co.uk/ . There's a guy living in one, full-time as far as I know, in Shamrock Quay marina in Southampton.

Pete

That is the original, built for the father of one of the owners at a cost of £160k if memory serves. Featured in a TV programme earlier this year.

The OP could look at using old marina pontoons or walkways. A couple of 8 or 10m sections would do.

 

[mikehibb]

https://www.gumtree.com/p/boats-kayaks-jet-skis/steel-pontoon/1322043247

 

[ningcompoop]

Much to my family's great annoyance, I've watched the whole two series of 'My Floating Home'. The range of floatation used includes, from memory, reinforced concrete "bath tub" bases, specially constructed steel boxes, sealed-up lengths of large diameter plastic pipe, large expanded polystyrene blocks and large logs. I was quite surprised to see both the logs and the polystyrene blocks used (in the US) for large, expensive constructions as I would have thought they wouldn't guarantee long-term stability due to water ingress, but both methods seemed very popular. I'd suggest watching a few episodes - https://www.channel4.com/programmes/my-floating-home - if you've never watched it.

 

[prv]

I was quite surprised to see both the logs and the polystyrene blocks used (in the US) for large, expensive constructions as I would have thought they wouldn't guarantee long-term stability due to water ingress

Raw logs surprise me a bit too, though I guess it could be ok with a knowledgeable selection of the species. The "pontoons" in the Kiel Canal lock when we went through in 2001 were just baulks of timber floating directly in the water, and they looked like they'd been there a good long time without any deterioration.

As for polystyrene, that's what the vast majority of pontoons in the UK use, albeit with a thin rendering of cement. I don't think they absorb water at all - the main problem is that if one gets bashed it releases quite a bit of pollution in the shape of tiny polystyrene beads.

Pete

 

[savageseadog]

Raw logs surprise me a bit too, though I guess it could be ok with a knowledgeable selection of the species. The "pontoons" in the Kiel Canal lock when we went through in 2001 were just baulks of timber floating directly in the water, and they looked like they'd been there a good long time without any deterioration.

As for polystyrene, that's what the vast majority of pontoons in the UK use, albeit with a thin rendering of cement. I don't think they absorb water at all - the main problem is that if one gets bashed it releases quite a bit of pollution in the shape of tiny polystyrene beads.

Pete

I think bits from Holyhead Marina will be floating around the World's oceans for hundreds of years

 

[cherod]

Johnny,, whatever you are making it out of i would doubt that a 10' beam is sufficient re practical stability .

 

[William_H]

I think your basic catamaran hull will be best. ie twin floats. It is just a matter of what you can find at a suitable price consistent with ease of attachment of the deck. I think plastic probably like polypropylene would last longest. I googled floating platform found www.gmpoly.com.au/poly-products/pontoons-floatation-platforms in Oz who seem to think this is the way to go. Might give you some confidence or ideas and I am sure there must be someone closer in UK. ol'will

 

[fisherman]

You can do a lot with ladders with 200litre barrels lashed on. Glue the stoppers first.