How is it done and can it be done to an older boat?

yes it can be done to just about any boat. to do it properly you should be able to access all of the seam from the inside as that is where you can get you best strength. you will need to lay about a foot wide tab around the perimiter on the inside over the seam. you will also need to grind that area to get a good mechanical bond. the outside really depends on the shape of the lap joint as to how you should fair it out. what are you working on?

Thanks Dave. not working on it yet. just future plans. sounds like its a pretty big deal to do and i dont have much of a budget.

probably would cost a few hundred dollars in materials but boat would need a complete (pretty much) paint job after its filled. i always thought it would be pretty cool to do up an old 27 sport magnum like a gladiator.