I found it pretty easily- though a link would be helpful...
http://www.youtube.com/watch?v=PFliNR3wW_wLooks like some sort of plastic covering over the sidebar aluminum.
I have closed-cell foam over mine for padding (matches boat color). Many use neoprene...
I think the usual way to apply (foam) is to use contact cement, which I tried to apply very carefully- and still ended up slopping all over the hull surface. Should use some sort of masking when working with glue on an intact boat...
Anyone know how to remove setup contact cement from gelcoat surfaces?
Based on limited success in gluing foam/neoprene to the rails I have doubts about trying to glue plastic...
But there are discussions of various ways to lead the (elastic) trap lines around the sidebar without damaging the foam. I recently re-grometted my tramp and so put a grommeted hole for accessing the tramp line. It would still be nice to have a turning block underneath but I haven't gotten to that so far...