[Blue197320]

just make sure you have a way to hang the "cable" on the inside top of the ibeams. if you have it sittin on the bottom inside the cable will be sitting in saltwater while your out fishing. the trailer under my 20 has a hole drilled every few feet on th upper inside of the I and i just used a ty-rap thru the one hole and ran it around the cable and back thru. the head on the ty-rap keeps it from pulling thru. been that way for years already.
50' cord should do ya just fine. probably get it for about 10-15 bucks.