jet fins spring strups - some questions of details

[el-ninio]

I'm building a pair of spring strups for my jet-fins. I have two questions I'm yet to find answers for inthe web.
I'm using the McMaster-Carr # 3932K24 springs, and have size L SP original fins. From the 3 dives I've managed with them so far, it would seem that you have to set the length of the springs to exactly match your foot. not only is this the case, but it seemed that I missed the right size by about an inch in the first mockup.

how did you find the right length for the loop? are the springs colsed all that way when your foot is inside, or do they applay pressure on your foot' pushing it into the socket?

The McMaster springs are 11" long, and the total length the loop is the length of the spring + the two blocks on both sides. the effective block length is should be messured from the pin going through the fin attachment point to the pin gooing through the block and holding the spting's loop. 75-80mm total (both sides) seems to work well for foot size 44/45 (10/10 1/2 US?), but I would love to hear what you found to be right.

the other issue is the length of the restriction cord. I made mine by sowing loops at the ends of a weaved cave line(?), but I don't know what the right length should be. what did you use? if the line is too long, it will not protect the spring, and if it's too short, it will not be comfertable to put them on.

 

[Birdman]

For spring length, I stuck my boot in all the way and then measured from hardware post to hardware post. I ended up taking about 3/4 of an inch off of the measured distance ultimately to get what I needed. It took me one intermediate step to get there (I cut the spring twice). I use boots with a lot of insulation. There is definitely a little tension on the spring with my boot in place the way I have it set up. If you use booties, I would say be careful as I could definitely see how the spring could end up digging into your Achilles tendon.

 

[wetman]

I recently took the restriction cord out of my spring straps and cut another half inch off the springs just to snug them up. They are and absolute joy to put on and off now.

Just try them and if they arent snug enough, take of another half inch or quarter inch or whatever you're comfortable with.

steve

 

[Zerogravity]

I made a set for my force fins, I also have them on my Jets. I had to cut the spring down from 11.5 inches to 8 inches to get the proper fit. All you have to do after that is make a loop on the end you cut, attach your cave line and you're all set. Cut A little off the sprig at a time, or make very sure of the length before you cut so you don't ruin the spring. ZG

 

[klausbh]

I don't use blocks to connect springs to my fins at all. I just hook the spring right onto the original hardware. A small piece of original rubber strap keeps the "buckle" locked closed (back) and prevents the spring from sliding around. Lucky for me, 11" springs fit comfortably without modification.

-Klaus