You can get high strength dyneema webbing from McMaster - 1" wide rated at 7000 pounds breaking strength. It's not cheap but dyneema is UV resistant, salt water resistant and is considered abrasion resistant. If you set it up running longitudinally on your boat then the lack of stretch is not a problem. The geometry gives enough shock absorption coupled with your tether itself to not be a problem.
I am a firm believer in having everyone on board walk through how to move around on the boat tethered in before shoving off. I've yet to see a boat with a "perfect" tether system where you don't have to switch connection points at some point. Walking through the whole system usually a couple times working out all the details of where you do what I consider very useful. I also test to make sure my tether system at no point allows me to be thrown outside of the lifelines at least at critical locations - especially working at the bow or mast. On my boat I have granny bars at the mast which are really nice but I've been on plenty of boats that don't have them.
It can take a lot of planning to get tethers placed to make their use both simple and such that you can't go over the lifelines.
In my opinion, it's especially critical for solo offshore sailors to have tether systems very well designed and built. All the electronic gizmos aren't doing much to keep you alive if you are more than 200 nm offshore. All they really do is make finding your dead body easier. The probability of another boat being close enough to reach you in time to save you is very small. At 200 NM offshore, it will take a minimum of 48 hours for SAR personnel to reach where you are. The probability of surviving for that time frame is extremely low, even less so if you are sailing in higher latitudes.
It seems to me that currently we spend a lot of time "shopping" for safety instead of designing and building for safety. I'm not opposed to all the electronic gizmos, but I feel the focus should be on designing and building a system, or systems, that simply keep you on the boat - and knowing how to use them.
In my opinion, the primary focus needs to be making sure nobody can fall off the boat. Get that down first, then work on the backup systems for the location of a MOB. It sure feels to me the focus today is flipped with "let's get all the electronic gizmos" - then let's talk about keeping people on the boat. Well at least we are talking about keeping people on the boat - although a bit superficially. However, the problem with going deeper than that is it becomes boat specific.
dj
