Buying Spectra

[Shuggy]

I'm just about to rig up a preventer and want to copy one I used last year on a different boat. They had a length of Spectra (unbraided/unsheathed, whatever the technical term is) which was both neat and easy to handle. Trouble is, I can't find anyone selling it. Any tips as to where I might get hold of a 7 metre length of something of a suitable suitable diameter?

Thanks.

 

[planteater]

I think Spectra is the American name for Dyneema. I might be wrong, though.

 

[Georgio]

I think Spectra is the American name for Dyneema. I might be wrong, though.

Yep, I think they are the same also.

Spectra/Dynema is probably way overkill for a preventer, save money and use a regular polyester braid-on-braid that will be easier to handle.

 

[Twister_Ken]

Kinda worried that as Spectra doesn't have any stretch then it might put a big shock load into the boom or deck gear, causing damage, if it prevented a gybe without being bar tight first.

Wouldn't nylon or polyester, with a bit of give in it, be gentler on the rig and hardware?

 

[bobgoode]

3 strand nylon is better than dyneema as you will have more give and hence avoid some of the shock loading. Also the dyneema can be stronger than the fitting!

 

[Shuggy]

Ken/Bob

Having trawled through the 'preventer' posts on here I know there are two schools of thought on this - stretch vs no stretch. However, I do know from having tried one on the same model of boat as we own, that a bit of stretch in the line is not necessarily a good thing - as given the angles involved, it's pretty easy to get the line to stretch and therefore allow the boom to move.

What I liked about the spectra was the small diameter required, the suppleness of the non-braided line (unlike braided Dyneema which I played with in a chandlery last weekend and found to be very stiff) and therefore the ability to keep it permanently rigged without making it too obvious.

FWIW, I would envisage having the preventer fairly taught on a winch when in use so that jerking is not an issue.

So - given that, does anyone know where I can buy what I'm after?

I am allegedly a bit pig-headed!

Thanks.

 

[bbg]

According to one forum on the 'net

In very brief, it's the same basic raw material, turned into fibers via two slightly different processes; Spectra's patent is held by Honeywell International, and Dyneema's patent is held by the Dutch State Mining Co.

I would have thought 4 mm dyneema would be sufficient for your application. Breaking load is 1.3 tonnes - enough to lift my 21 footer. But it won't be very easy on the hands, so you might go for 6 mm or even 8 mm including a cover. You also probably want to incorporate a safety valve into the system - a short length of lower strength line in case the boat broaches.

If you use dyneema / spectra it won't break. The fittings might. The boom might. But the rope won't.

 

[tudorsailor]

My preventer is braid on braid. Coming across Biscay last year with preventer tight on winch, had accidental gybe as there was enough stretch for the boom to come across the midline. Now thinking of making the preventer all dyneema maybe again from Jimmy Green

TS

 

[Shuggy]

Thanks TS - if you work out what kind of Dyneema would work best, could you add a post here please?