I think that was kinda the idea - war production meant steel was in great demand, and this seemed like a really cheap way to make ships. I wouldn’t want to try sailing one round the Caribbean, but they might have been okay in the north sea, for example. They didn’t work out though, can’t recall why but it’s not impossible that melting may have been a factor!

IIRC this type of thing isn’t new - there was research into the possibility of making ships out of ice mixed with sawdust in WWII.