We were just talking last night about the flooring we are using in the house. We think it could be a great option in a narrowboat. It's actually from a UK company called Karndean. The boards are vinyl and just get laid straight down onto the level surface beneath. The product is called Looselay. At first we were a bit skeptical about the idea of it not all being glued down but having seen it successfully used in a commercial environment we were sold. The perimeter of the room does get stuck down and in our case we need to use a special two pack adhesive in the bathroom and laundry to comply with wet area regulations. The rest of the house the boards can be lifted back up and replaced or swapped around if necessary.
It has turned out to be a pretty easy installation with very minimal waste. They told us to allow up to 10% wastage when we ordered it but it won't be anything like that. We have been using the off cuts from one row to begin another row so that the joins will be staggered. The only time an off cut can't be used is if it has been cut by us at both ends. It needs to be the perfect factory edge that meets the next board. We have about half a dozen pieces left over like this now (halfway through the job) but even they won't be wasted. We figured we can use them under the feet of the bed or other furniture that might mark the flooring.