Line for preventer?

[Brion Toss]

Hi there,
I used to use Sta-Set for the deck pieces, and Regatta Braid for the boom. The Regatta was the short run, so didn't stretch much, but it had enough give that it could absorb shock loads. The Sta-Set was too elastic, though, so I switched to Sta-Set-X. Now that that is becoming scarce, I might go to VPC or the like. Oh, and nowadays on the boom I use Spectra, but with a short piece of bungy cord inserted, for shock load. The Spectra is much lighter, doesn't soak up water, doesn't hang down so readily.
5/16" for a preventer on a 36ft boat? Way overkill.
As for the weak link question, there shouldn't be one; anything in this system that can be counted on to part in an emergency can be counted on to part when you don't want it to.
Fair leads,
Brion Toss

[JohnV]

I'm confused--if Sta-set is too elastic, then why insert bungy in Spectra for shock loads? Or is the bungy just to keep the Scectra taut when it's not in use?
I'm trying to figure out the best combination for my 33-footer.
John V.

[JohnV]

Wait a minute---(smack forehead)---if you put the bungy inside the length of the 12-strand, then stretching the bungy keeps the line taut. But stretch it more, and the dyneema takes over the load.
Elegant.
Wonder if anybody else has thought of it...
JV

[matt the rigger]

The lower stretch the better. I agree with Brian that there should not be a "weak link". And the shock cord in the line has been done for years.

[Brion Toss]

Originally Posted by matt the rigger

The lower stretch the better. I agree with Brian that there should not be a "weak link". And the shock cord in the line has been done for years.

Yes, true, I have done it for years. The first place I saw it was in a 3-strand mooring line. That would have been somewhere around 1980. You'll find a description in the Apprentice. Since then I've been playing with it in a variety of constructions, currently in mooring lines.
Fair leads,
Brion Toss

[memelet]

Sorry for coming back so late; I did not realized I had my responses.

Originally Posted by Brion Toss

Hi there,
Oh, and nowadays on the boom I use Spectra, but with a short piece of bungy cord inserted, for shock load.
Brion Toss

Hmm, I put in the shock cord but really it seems to only keep the line taught when attached to the boom and not in use. It only takes a couple of pounds before the amsteel takes the load. Am I doing something wrong?

Originally Posted by Brion Toss

5/16" for a preventer on a 36ft boat? Way overkill.
Brion Toss

Did I say 36ft boat? Well is 42, so probably not that much different. The 5/16 is the amsteel on the boom. I used that because I had it left over from the life lines.

So I gather that I should warp speed or something similar for the deck pieces?

[Brion Toss]

Hi again,
You are likely fine; the bungy is just there to dampen things in use, as well as to keep the line snug when stowed. Remember, even a little snubbing action reduces shock loads tremendously. As for line size, by all means use what you have on hand; just know that the breaking strength for that 5/16" Spectra is probably at least 6 tons. Let's just say you have a generous safety factor.
As for the deck pieces, Sta-Set-X (we are having a special on that right now) or VPC would be better choices than Warpspeed, which is a bit too inelastic/spendy for the job.
Fair leads,
Brion Toss

[JohnV]

"Wonder if anybody else has thought of it..." was a try at humor, after I was so slow to figure out what the bungy did--Never mind.

My bigger question is: how much of a handicap would it be to use only one deck piece, turned around a block centered near the bow, say at the staysail tack? Given a cruiser, where speed is less critical, would the added trouble to unclip the deck line from the boom line, bring it around under the lifelines and outside the stays, and re-attach it on the new lee side--outweigh the added complexity and cost of twice the number of side-deck lines and turning blocks?
For that matter, might you make the same case for only one boom piece?

I couldn't find it in "Apprentice", btw. I assume I can stitch the bungy in place by putting a couple stitches through each of the spectra strands?
JV

[allene]

I use a bow cleat for the turning block. I want to add that I think it important that the line be long enough that you can release it at the cockpit and gybe letting the line free so follow the boom over to the other side, then attach the preventer on the other side after the gybe is complete. You could use two lines but you end up with a lot of line in the way of everyone for the lazy preventer.

[JohnV]

Sounds like we're on the same track, Allene.
My tentative plan is to run 50 or 60 feet of 5/16 staset-x from the cockpit through a series of fairleads that are already along the bulwark on one side. I'll double it back through a snatch block by the staysail tack when I'm using it, or else just leave the ends coiled and out of the way when I'm not.
I'll see how I like it with one spectra line on the boom end with the option to mount one on each side later.
John V