Jim, Yes, the load rating is very important. But it is hard to compare load ratings sometimes, because it's not always easy to find the load rating on some rope. Plus, it's hard to guess just how hard each person is pulling when the boat yanks you off the dock. I'm sure you could make an educated guess, and throw in a significant safety factor, but it's still a guess.
Yes, Not only that, but the really strong stuff is the plasma 12 strand which is is more difficult to splice. jim
On our twin rig, we have a closed eyebolt attached to the transom between the two motors. We attach a 10 foot nylon lifting strap to that, with a piece of rope that the observer can pull back into the boat, to hook up other ropes, or trunk lines. We also have three smaller nylon straps about 20 ? feet long. We will sometimes attach the 20 foot straps to the main strap attached to the transom. All the lifting straps, shackles, carabiners, ETC. I believe one of our team members got from a rigging supply company. You might also find lifting straps, and other equiptment from Graingers, or other industrial supply company. Our ropes are just the normal 90 foot pyramid ropes most every team uses.
It's nearly impossible to calculate the exact strength of the rope you need w/o some sort of extensiometer because of the shock/impact of the pull off the dock. Sure, you can simulate the load (weight) of the skiers and the speed of the boat but ropes get old, UV rays make them brittle, just too many factors. I'd say we know enough through trial and error to guess on what kind of ropes you need based on what other ski teams are using, and if it breaks go buy a bigger one!
I think you missed my point. One of the posters complained that the ropes were getting too big to handle. Most manufacturers quote the strength of their products. If you have one that works, then fine. If it breaks, bigger might not be an option. A better stronger one might be. jim
Yes, I may have confused myself. My point to going bigger was in regards to the same style/type of rope used. Choosing a different weave or material could definitely give you a stronger rope in a smaller size.