Stopper knot in Amsteel

[dmonn]

I posted this on the climber's forum, but thought splice guys might be interested in chiming in.

I've got a sailboat application for this thread. I want to use a stopper knot (jam knot) for a single strand of 5 mm Amsteel. Two questions:
1. Does a stopper knot weaken the line?
2. What's the best stopper knot to use for amsteel? Burying the tail may not be an option due to the size of the hole.

For the application there might be 500 pounds of mostly static force on the Amsteel shared between two stopper knots.

TIA

Don

 

[evo]

Knots severely weaken amsteel. The only times I’ve ever seen it break is when a grapevine (double fisherman’s) knot was used on a chipper winch line. I don’t know what the max pulling power of the winch is but it’s well under the working load limit of the line. It almost always broke at the knot!
It’s also a very slippery fiber, knots will compress ALOT! Or the tail will pull though.
500# isnt a lot though. And I’d guess if you stay within a comfortable WILL it will be just fine. The biggest risk would be cyclical loading
Can you splice some kind of toggle on the ends? Or shackles?

 

[Brocky]

 

[dmonn]

Thanks. I've tied it enough for today to be quick and confident. We'll see how I do with it tomorrow. I assume it's like a button knot or diamond knot where you want to dress and set it pretty hard before using it, mostly to prevent roll-out and give it strength. True?

I'll leave some tail on the knot, and do a smoothed fuse of the end. For 5 mm cord, do you think 15 mm of tail would be enough?