shock cord fin straps

[seamusv]

So, I was playing around in my basement yesterday, and I came up with these fin straps. They're really simple and cheap(these were free since I already had all the stuff). I haven't tried them out yet. I couldn't find anything similar in the archive. Can anybody think of any issues that might arise? The only thing that occurs to me is that the shock cord will compress at depth. Could it compress enough to slip through the zip ties?

 

[Matt S.]

I use shock cord like that for my compass mount and haven't noticed it compressing at depth.

Not a bad idea... I will be curious how the cord holds up in that application.

 

[redacted]

I used it on a pair of Jet Fins that I just was not ready to commit to spring straps. I have used them maybe 10 times in the last 5 years with no problem. Shock cord (bungee) is rubber & nylon (solids) and does not compress with depth.

 

[Akimbo]

I have been doing some experiments with fin straps as well. You may find using half the clip that connects the strap to the molded post on the fin a more reliable connection on some models. I found it is difficult to get the bungee wrapped around the post tight enough so it will not stretch and pull off under normal use.

 

[seamusv]

Thanks for the replies. Shock cord doesn't compress at all, or doesn't compress a noticeable amount? I would have thought it would compress somewhat if only a negligible amount. Also are spring straps superior to the shock cord ones? If so, why?

 

[redacted]

Gasses compress. Liquids and solids do not. So you should not see any change of volume unless some gas bubbles are trapped in the rubber.

 

[Seraphimx]

The shock cord is made of multiple rubber cords, the spacing between them will become smaller and smaller, until it reaches the "real" size of the cord.
The shock cord will get thinner, but I guess it won't affect it's capacity to hold what you want. It may cause a change of 1/8" or 1/4" (wild guess) but not so much as to change the pressure applied on your boots. Just put them tight, not too tight, at the surface and it could work.

 

[redacted]

The shock cord is made of multiple rubber cords, the spacing between them will become smaller and smaller, until it reaches the "real" size of the cord.
The shock cord will get thinner, but I guess it won't affect it's capacity to hold what you want. It may cause a change of 1/8" or 1/4" (wild guess) but not so much as to change the pressure applied on your boots. Just put them tight, not too tight, at the surface and it could work.

Or would any spacing that might exist between the strands of rubber be filled with water and no volume change would occur?

 

[Brendon]

I agree with Akimbo, go thru the buckle. What you have set up there will likely come off underwater.

 

[Peter_C]

I have seen people use bungee cord with much success for fin straps. Most people use the regular sized bungee cord that is pretty thick. More strands equals more holding power.

In the first picture I would worry about two things. One the shock cord popping right off the pin. If you can attach something to the pin, then attach the shock cord to that, then it is a viable solution. Otherwise lose what you got now for fear of your fin going bye bye. I might even have something from an XS Scuba spring kit if you are interested. The second thing is those zip ties suck. Get the ones from Home Depot or the like with the metal tang. Use the metal tang ones for anything critical, and the cheapo ones for everything else. My preference would be a whipped end though. Thread wrapped around and fed through with a needle would be clean and have plenty of holding power. Either way works though, just use the right zip ties.