An idea of renovating a scrap/disused ferry or large boat, for renovation into a house. How could I find these kinds of scrap boats.?

I am not clear if you want to make a houseboat out of it or use it on land. I saw the pilot house of a Great Lakes ship was used to make a house on land, very cool. Check out this link. http://1800recycling.com/2011/01/recycled-ship-houses/ Finding one may be harder, but they are out there. Look in a publication called Boats and Harbors.

Have you got a boatyard? How's your welding. The cheap ones need lots of plating. Really hard work.

Richard C has it right . Most people use old steel cargo barges , things like Thames Lighters , but the problem is often that they are corroded underwater and very thin , very knocked about , and the effort of hauling them into a yard , cutting out the scrap plating and then getting new plates made and welded in is more trouble than the thing is worth . They are disused junk for a reason . The concrete barges mentioned by adaviel were a wartime expedient to save on scarce shipbuilding steel and shipyard labour and shipyard space , built on a steel rebar mesh frame these were cast by labour unskilled in ship / boat building in moulds on any handy hard surface near a waterway , Many have lasted far longer than was intended , but you'd be hard put to find one in fair condition today . Interestingly many were the product of the Marley Tile Flooring Company in the UK , only God knows what desperate expedient of beating ploughshares into swords brought them into the barge building profession . As you basically just want a big steel box built for you , I'd suggest you talk to a local shipyard about the standard sizes ship building plates come in from the manufacturers , and prices , then pencil sketch your box around those ( aiming for the minimum amount of cutting , bending and lengths of welding needed ) Work out your maximum weight of what you want to put on it , times that by 2 to allow a healthy safety factor , and then ask them to price the job for you . Let their designer go over your plans, and ask if their foreman welder would please look at your ideas and suggest any savings , short-cuts and so on . Dont forget you need a lot of fittings ; -- like ladder "loops " for climbing up out of the water , mooring bollards , railings sockets , upstands to fix superstructure to , Boarding gangway frame and hinged deck-edge attachment points , loop " eyes " for tying stuff to , all around the deck edge , fender tying eyes around the waterline , and heavy duty towing points . Design most of that from simple scrap plate / bar / strip / tube offcuts kicking around their scrapheap ( or fossick around a local scrapyard to find suitable scrap stock , and make everything Brick-Sh*thouse strength , because you have the luxury of not having to skimp on weight or strength . I say ask a shipyard , because then you will get it built in inch thick shipbuilding plate on bottom and sides , and NEVER have to worry about " remaining hull thickness " ever again , nor minor collisions , and so you will sleep soundly at nights .

My cousin did that. He got a WW2-era ferrocement barge from somewhere - I'm not sure of the details. Anyway, the thing's grounded in a river estuary in Britain and he cut a doorway in the hull. There's a few other "properties" nearby like that; I think they have some kind of legal loophole that means they don't count as houses and have to pay tax.

Relatively large ferro boats can be had cheaply sometimes. Just learn to survey them. They are subject to galvanic corrosion just like steel boats, but it can remain hidden in the mortar. The basic rule of thumb is that the engine compartment and any other place where oil can come into contact with the mortar should be epoxy coated. The rest should not be epoxy coated. Go around the water line and scrape off the paint in several places and it should still look like good fresh plaster. Not spider webs or anything else weird. Check the lowest points in the hull for holes (because that is usually the first place to go with corrosion). Also scrape and inspect around any bronze thru hulls (or any thruhulls for that matter, because a nylon one might have replaced a bronze one). A good in-build survey can be very valuable. They usually include test lab results of mortar strenght from every pour. Ferro is an awesome material once one learns its "warts" and workarounds.

Well unless you have a few hundred thousand to spend this will never float! The Ferro cement barge sounds like pure fantasy as barges were metal except the old wooden hulled sailing barges! Try Applloduck but it will not be cheap!