Re: Double or single lifelines?
Yes, any line of any material is weakened if it's bent around a radius smaller than what is recommended. For instance, most rope manufacturers suggest an 8:1 ratio. So for 1/4" line you need a 2" sheave, thimble, whatever. I can tell you that you probably won't need to worry about it breaking. The stanchions will absorb a lot of the shock load. I just splice mine to the ring on the pullpits or lash them there. I'm using 1/4" line which works really well. 8600 lbs breaking strength is a little much and I'll probably drop it to 3/16 when I replace it. But the stuff is cheap and easy to splice, it's not like it takes 1/2 a day to change them out, or longer like it would w/ steel.
I use spiderline for lashing. Dyneema core with poly cover. You can use "Lash-it" as well, but it's more expensive and doesn't hold knots as well. I would change out the lashing every year as cheap insurance. A mini spool is only $16.
Merit 25 # 764 "Audrey"