I'm knee deep in the new dinette project and, as with every project, I find you always need a couple of more clamps than you have on hand. In this particular case a couple of four-foot bar or pipe clamps come to mind.
Pipe clamps make the most sense on a boat because you can always, make clamps to fit your needs, dispose of the pipe when you don't need it, and 3/4" pipe is pretty much available anywhere you find yourself.
Listening to Josh Brooks
So it goes...
