Using "dynamic" rope as a safety line

[allene]

I got the bright idea of getting some mountain climbing dynamic line to use as a safety line when climbing my mast. I like the idea that I can have this little gizmo that I put a carabiner on and it just follows me up and will grab me if my main setup fails without cracking my ribs from the lack of give. (I pull myself up without anyone on deck). But I find that this line has something just under 10% stretch against just my weight. So if I want any protection when at the top I run it up the mast, through a block, and back down. Now I have 80 feet of line which will stretch 8 feet if I just hang on it. I would guess I could get reasonably high and yet still hit the deck if I fell. But if I use a single section, there is no stretch when I am at the top. OK, so I could tie two lines together and have some low stretch line that I actually put the ascender on and have a 40 foot section of the dynamic line going up to attach to that line at the top. That gives me a constant amount of line I would be falling against.

Does anyone have experience with this kind of line and if so what is the correct way to rig it for this application?

Here is a picture of the little ascender. When you pull up, it freely goes up the safety line without having to take your hands off the main line. I really like that part of the setup.



Allen