Anchor line or tiedown line??? - you imply it's anchor line, yet you suggest it won't scratch the car - dual purpose???
If you use poly line to tie down over hood and trunk of car, put down 'chafing gear' underneath. Either nylon or poly over paint should be chafe protected; an old cotton towel, expanded foam pipe insulation, whatever you think suits your needs.
Nylon line should be rinsed if you don't want it to stiffen up from salt exposure, and it ought to last a good while. It might hold sand and crap in it's fibers more so than poly if you drag it around, etc.; poly doesn't rot, but is prone to UV dryness and damage, as well as less resistance to fraying over time, etc., blahblahblah.
I own and use both types; hauldowns on the truck are nylon (it runs thru eyes more smoothly) and I don't have roofracks, so it's all tensioning and placement. Poly gets similar rough treatment. Your mileage may vary.
P.S. - poly doesn't float with an anchor on the end unless you lose it overboard altogether, then it'll float in a relatively straight line upward.
Last edited by DFix; 04-10-2002 at 12:11 PM.