I use rubber "o" rings and camping hooks. The "O" rings are from a 5" ceramic sewerage pipe. Tie them to the trailer and experiment a touch to get the right tension. I use gal "S" hooks on the "free" end and simply hook it to a chain link welded to my trailer.

It is very fast and easy and I don't have to worry about over/under tightening of the straps if somebody else ties it down. I have towed my boats all over Australia with that setup that works well <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Tiger Mike