Besides the cost of a replacement, there's tank installation, which can be labor-intensive. Boats with accessible compartments, like those with a deck seam around the console, are obviously easier to work on. On boats without easy access, the deck usually has to be cut to remove the tank. Afterward, the deck has to be reglassed. If internal flotation foam in the hull is soaked with leaked gas, it has to be removed with hand tools since power tools might give off a spark. No matter how you look at it, replacing a tank is not a cheap proposition.