Thanks for the kind words Vinny........ You know, there's different UV ratings for different vinyls. Automotive vinyl has a rating of 300 hours. Vinyl used in spa covers is typically rated at 500, 1000 or 1500 hours. Ok, so how this rating actually relates to how long vinyl will last, I don't have a clue (not really, just not enough to try and explain it). However, the higher the rating, the longer the vinyl will resist sun damage. I've seen covers 2 years old starting to show sun damage, and I've seen 6 year old covers where the vinyl looks fine (all in direct sunlight).
Can you explain this more? When I initially came up with the Blanket Leash I did have concerns about the strap pulling through the blanket. In an effort to prevent this, I fought hard with my partner to go with the biggest (and of course most expensive) plastic (actually PVC) washers I could find for the backing. I figured bigger would spread the strain over a larger area eliminating, or reducing, the possibility of it pulling through. But, apparently, for some people it isn't working as well as planned. As you may recall, I got this free spa I put at my GF's house. I'm planning on using it, among other things, for experimenting (I might even experiment with some spa stuff 
). hmmmm, I wonder if something more cup shaped, concave (or is it convex?) would work better as the edge wouldn't be in direct contact with the foam when the cover is opened? I tend to think that the most strain is caused when the cover is initially opened, and the foam has to be pulled free from the suction of the water....Or, do you think the beginning of the tear was caused by the shaft of the rivet?
Doc,
The best I can explain it is the foam has no structural integrity. The stress on the area being lifted by the spa leash rips through the foam. Water does have an adhesion property and the foam you use seems to get "adhered" to the water along with the weight of the blanket (and the little bit of water) itself. I put a patch of 5"x5" duct tape on the upper side of the blanket with the rivet in the center. I believe that the duct tape with it's cloth backing gave enough structural integity to allow the washer not to rip through. I also only used 2 leashes and not the three that caomes in the pack ... the more spots for lifting the less stress on each area.
Personally, I don't think any shape will stop the pull through. I think it needs something large to either distribute the weight further or somehow give the blanket structural integrity (hard foam has some integrity I believe). I also thought of gluing velcro to the ends of the leash and to the blanket and see if that works any better.
Honestly, the blanket that I have now would not be able to handle the leash.
