Rotten Cotton Found

Now google rotten cotton crotch.  You won't be disappointed.

I might have used wrong link.  I got the 120 twine.  It should be more than enough.  It's only meant to hold a side of the trap closed. 

http://www.captkhanhtacklebox.com/Crab-pot-door-kit-89.htm

Here is probably the best alternative I've seen, rather than diy.