I installed a course through the ice in January and will be adding the submersion feature in May. I have 700 feet of 3/32 cable that pulls the course down and is suspended across a valley with matching flotation to keep it from sagging or floating. This is a repeat of a submersible design I did on another lake many years ago that worked well for three decades until we moved to another lake.
In the event someone catches this cable with a boat anchor, I need a break-away feature to keep this from wrecking the course. I intend to put the "weak link" in the middle of the cable.
Normal tension for winding and holding the course down is around 300 lbs. I want the break away to happen around 400 lbs. I have been testing commercial cable ties with a tensile scale. 4 wraps with a 50 pound tie binding 2 stainless steel fittings breaks at 400 pounds. This is consistent with the fact that most commercial ties break at 2x their specified strength.
But I don't think cable ties will be reliable with frequent release and reload cycles that are within 75% of their break point. I think their break point will decline with constant reloading.
Any idea on another material to use as a break-away link that won't deteriorate with load cycles. For example a small high density poly rope that breaks at 400 pounds would probably be better, but I am just guessing.