[hellosailor]

Marty, do you clip in with one hook or two?

There should be no problem getting past shrouds or anything else. One hook (one snatch hook on your tether) is no loner considered good safety, the modern trend is to ahve two hooks, one short, one a bit longer, so that you use the short tether, and then snap the longer one past an obstruction in order to move past it without needing to unclip. (The obstruction typically being the mast.)

Any safety gear is a PITA, but so is going overboard at sea.

 

[hellosailor]

Marty, anything probably beats nothing. But I'd pass on the twisted line, it is too easy for that to act as a roller and roll your foot off the deck and you with it. The preferred material is tubular nylon webbing--not flat, and not poly. It is readily available, discounted, from webbing suppliers on eBay and other sources. That's also a handy material for many other purposes, so don't be afraid to buy some excess.

The 3-twist...is best for strapping packs on mules, or dock lines.

If your old single-clip line (mines form the same vintage but I've added a carabiner on a second line) is just a plain spring-loaded clip--be careful. It is oddly and easily possible to take a single spring clip and UNHOOK it from the line, just by rotating it against the line.

I found that out when I used them for diving tethers, and couldn't figure out how the tethers were getting unhooked all by themselves. The real one on my harness has one of those safety bars across the middle of it, you need to squeeze it before the main hook can open.

 

[hellosailor]

isus-
As bubb says, bad idea to clip onto the rail. If you have a three foot tether clipped onto the rail, that still allows you to go three feet overboard when the boat tacks and the high rail becomes low side. Better to clip onto something on the centerline.