Leashes.

[PonoBill]

If your leash is two years old it's marginal anyway. I test all mine to failure each year--if I haven't already done that in the surf. Test day 2018 is coming up soon. You might wonder how many have broken or pulled out the swivel over the years. Three broken, three pulled. Creatures of Leisure leashes often use a pressed in swivel on the cuff with no screw or pin retaining it. Admittedly that sends the swivel the wrong way to injure you but might not do your board much good. I don't know the total number of leashes I've pulled apart with my truck and the post in the middle of my garage, but figure I've been doing this for ten years and it's probably five leashes per year. So fifty leashes, six projectiles. Twelve percent. Don't be afraid of sharks, be afraid of leash swivels.

Maybe I can get Diane to shoot video this year.

[supthecreek]

Question:
After a fall, your leg is underwater
I imagine the volume of coil meets significant resistance from the water...
The “spring back” must be reduced dramatically when interactiing with a liquid.
Would it pose the same tbreat underwater as in the air?

I would never wear a coil in surf for the very reaso that it meers too much resistance when dragging in water, and slows you down. 

[Bean]

I would agree STC.  In that scenario, I would expect that the swivel would be dragged harmlessly through the water.  But what about when you launch yourself off the lip? Huh?

[mrbig]

Waist belt with a half coil works fine for me. Never ever step on it, no drag, and I had one break in OH waves and nothing went whizzing by. I learned to swim. YMMV!

[PonoBill]

Question:
After a fall, your leg is underwater
I imagine the volume of coil meets significant resistance from the water...
The “spring back” must be reduced dramatically when interactiing with a liquid.
Would it pose the same tbreat underwater as in the air?

I would never wear a coil in surf for the very reaso that it meers too much resistance when dragging in water, and slows you down.

My testing of coiled leashes started when I read a post by someone who had a swivel bury in their board. I didn't believe there could be any additional force applied from the leash being coiled. I was wrong, the force is substantial. Having your leash snap back at you is no big deal, until it suddeenly. If that wasn't kind of important we'd still have leashes made like bungee cords, and Jack O'Neill would have had two eyes. The reason leashes are made of urethane cord is that it won't snap back. Modifying the Urethane so that it DOES snap back and taking that into big surf seems a bit counterproductive.

In the most energetic situation, where your board is stuck in a wave and you are being dragged, your foot is near the surface and your board is above it. Having your leash break then is nasty enough without having the leash come at you like a whip. There are a dozen reasons why coiled leashes aren't a good idea for surfing. This is just one more.

[ospreysup]

Coil=Recoil!  If that is what you are looking for great but recoil in the surf just doesn't seem like a good match to me. I know when I get caught inside the last thing I would want is a recoil. The board is attached to you so it is going to recoil at you.  Can't see that being a good thing if you get caught inside.