dock "line"
George,You could use either 3/8" or 7/16" and be comfortable, I have a 27' and use both 3/8" and 1/2". As far as three-strand nylon line goes, if you mean a three-strand twist, I wouldn't use it to tie off my boat. I use a double braid line, I feel that it handles the load stress better than three-strand.And buy GOOD line, like New England Ropes or Yale. Hardware stores sell rope and belive me the quality is different, go to a marine store, the extra money you spend will pay off in the end.I hope this was helpfullgood luckRichJ