Steve Laume wrote:......The video of the dynamic tests on slings was very interesting but I am not so sure it transfers over to sailing all that well.....
On a boat I suppose you could see forces similar to what you would have in a free fall but it would not usually be the case. As far as generating the kind of shock loading he was showing with that set up, it just wouldn't happen. There is some give in your harness, body and the nylon tether. The biggest shock absorber would be in the jack line material and the fact that the loading would be off to the side. I think it would still hurt bad if you took a really nasty fall but at least it wouldn't cut you in half.....
It doesn't matter if you fall sideways, straight down, onto the deck, or directly into the water.
When your body moves through space, you move at a given velocity, or speed. That velocity/speed will differ based on your body weight plus added weight of clothing and gear. It will also vary based on the direction in which you move (vertically, sideways, etc).
The loads shown in the video were based on a load of 176 pounds falling distances of 2 feet, 3 feet and 6 feet.
According to the maker of the video, a climbing equipment manufacturer in Wales for the last 30 years, a force of 10kN or 2248 pounds, is enough force to cause internal injuries.
According to their tests, a static free fall onto a 2 foot long sling can generate 16.7kN or 3754 pounds.
If you have a 6 foot long tether and you weigh 176 pounds soaking wet in your foulies, and you free fall only the last 2 feet into water after going over the lifelines, how much force could possibly be generated that your tether, harness, and, more importantly, your body, are going to have to try to absorb? Will it be the entire 2248 pounds?
I'm considered "thin" at 180 pounds, plus clothes/gear. I'm guessing that most men are closer to the 200 pound mark, plus clothes and gear. How much higher is that force at the end of a 2 foot free fall with the extra 25, or more, pounds?
Even if the "sailing" version is only half the force shown in the "climbing" test, do you really want self inflicted internal injuries as you try to climb back on board?
If there's a way to mitigate debilitating forces in a bad situation, it's probably a good thing not to ignore.
I'm not trying to pick on you Steve, I just like flogging dead horses. They don't make as much noise.
I'm disinclined to acquiesce to your request. Means no.