I'm going to make a document of this topic for my class website soon, but I'll give you the run down.

I don't trust spectra, the guys I know who tried spectra broke their traplines. Everybody tell me this stuff is the same as Dyneema, but everybody that I know that hangs of dyneema has never broken a trapline in many years. Hence I trust dyneema and not spectra. I feel that dyneema appears to be alot more shock resistant. Or the friends who broke (all in anglo saxon countries) only have excess to inferiour grade lines. I know you have two choices in 3 mm dyneema. One is cheap 300 kg line and the other is slightly more expensive 500 kg line. You'll want the latter, The first WILL break and sometimes rather easily (as in by hand !) I think the cheap stuff is just, well, rubbish. No way I can pull 300 kg apart.

I have 3 mm dyneema 500 kg break strength. Others and I have dung of that for years and we leave our boats on the beach for 6 months. In full sunlight and weather. This setup is well proven. Several of use just use bowlines to tie them on to the mast shackle and it holds. I used a single line per side (two trapeze lines) that I wrapped around a plastic thimble and stitched into place. I did this to be sure that the other stays at the shackle don't wear down the trap lines at the top where I can't inspect them often.

I found that figure 8 knots don't seem to degrade the lines much so I used on up near the thimble (and stitched the loop in tight overthere. Then I made a figure 8 knot right below I wanted the plastic (RWO) handle to be. This handle rests on this figure 8 knot. Slide the handle on first of course. Then I have a loop on the bottom end (bowline or figure 8 knot loop) and I use this one to sailors hitch a shackle on or whatever. This last bit take the adjuster setup or the trapline to the dogbone or whatever.

That is it. Weight savings are at least 400 gram per couple of 4 traplines = 1 pound. (comparison 3 mm dyneema and 2 mm steel). But the best advantage is the dyneema lines don't wear down your mainsail (pockets) at all and they always hang taught even with very little bungee tension. This allows thinner bungees and other fine-tuning of the systems on board. Overall with the right modifications the new system will just work alot better and nicer.

In my class were we don't rule on details like traplines, I'm seeing D12 line being used as well and I think they are using 2 mm or 2.5 mm. This line is often of a smaller diameter under tension then the specifications; so in addition to weight they are also thinner then steel but with 500 kg break strength.

The dyneema and D12 lines will creep a little at first but after being tensioned a ffew times they are without stretch at all.


Good luck

Wouter