Rope for Guardwire securing.

Seashoreman

Seashoreman

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Aldeburgh, Suffolk. River Alde
www.pianotuning.uk.com
I would like to replace the rope at pushpit that secures guardwires.
The original looks like a common braided material, possibly about 8mm.
Not too keen on dynema for this important job as it seems a bit slippery and difficult to tie?
Any suggestions and/or specialist knots?
 
I use thin Dyneema with plenty rounds it’s strong and secure.
I use half hitches around the lashing and secure the end by putting under the last hitches
 
As I understand it, the role of the rope lashings at the ends of the guard wires is twofold. Prevent a complete electrical circuit around the boat and to allow the rope to be quickly cut to permit the guard wires to be removed at the aft of the boat to assist in a MOB recovery situation. Personally, I would therefore use polyester rope as it performs both functions well (and has the benefit of being cheap and so can be replaced at the first sign of wear).
 
Pinnacle said:
As I understand it, the role of the rope lashings at the ends of the guard wires is twofold. Prevent a complete electrical circuit around the boat and to allow the rope to be quickly cut to permit the guard wires to be removed at the aft of the boat to assist in a MOB recovery situation. Personally, I would therefore use polyester rope as it performs both functions well (and has the benefit of being cheap and so can be replaced at the first sign of wear).
Click to expand...

+1

You don't need very thick stuff, after all, 5mm polyester has a breaking strain of around 470kg, so 5 wraps, 10 lengths will easily hold a couple of tonnes, even allowing for the weakening effect of knots and bending.

Just beware of the cheap stuff from the Range and similar, which is polyprop. I used some for a burgee halyard once and it disintegrated after a year. The 5mm polyester I used last time lasted for years until I needed to slacken the guard wires for liftout. The half hitches securing it had tightened to the point where it was going to take too long to undo them, so I had to cut 'em.
 
Pinnacle said:
As I understand it, the role of the rope lashings at the ends of the guard wires is twofold. Prevent a complete electrical circuit around the boat and to allow the rope to be quickly cut to permit the guard wires to be removed at the aft of the boat to assist in a MOB recovery situation. Personally, I would therefore use polyester rope as it performs both functions well (and has the benefit of being cheap and so can be replaced at the first sign of wear).
Click to expand...

The "prevent electrical circuit ..." bit is a hangover from the time when we had RDF sets, and a complete circuit around he receiver could introduce quadrantal errors in addition to the potentail refraction errors that the system already possessed. As the transmitters were mostly switched off 20+ years ago it's not very relevant now.

I got new guardwires from a well known rigger/chandlery that came with thin blue lines already attached to one end. After six months I had to replace them as they were suffering UV "crumbling" - probably polypropylene. I normally use multiple turns of thin 2-3mm polyester.
 
As others have said, as long as it's not polypropylene you'll be fine and tuck the last half hitch in to stop the last hitch undoing. As you say - Some modern ropes are very slippery and half hitches do tend to undo.

As to electrical reasons - I put (non-conductive) rope sections in the guard wires after installing an HF vertical whip antenna on the transom... so the electrical break reasoning can still be true.
 
I use normal polyester 2mm with about 20ish wraps, if you use half hitches around the lot with a few feet of spare, you end up with a decorative "plait"... easy to lose the ends within the whole thing
 
knuterikt said:
I use thin Dyneema with plenty rounds it’s strong and secure.
I use half hitches around the lashing and secure the end by putting under the last hitches
Click to expand...

Exactly what I have had for 6 seasons now.
Will be replacing it by the same this season as a precaution. I had to undo one last year and apart from some discoloration of the outermost turns, it looked perfectly allright. It is 4mm dyneema.
 
While you may not be going racing the OSR rules are a good guide for many things.
3.14.6 d) A lanyard of synthetic rope may be used to secure lifelines provided the gap it closes does not exceed 100 mm (4”). This lanyard shall be replaced annually
**
3.14.6 e) All components of the lifeline enclosure system shall have a breaking strength no less than the lifeline
Click to expand...
 
just out of interest, why one piece wrapped several times, not two or more wrapped to make the same total amount. Just thinking, one snap and the whole lot unravels if it one piece, or is that part of being able to remove fast in a MOB emergency?
 
awol said:
The several turns are used as a purchase to tension the lifeline.
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I gathered that, just wondered why it is all one piece. It would be very simple to add a vertical loop between the upper and lower guardrail tensioners to acheive the tightness required.
I am not being smart, just curious, I am no expert on this matter at all. So please feel free to shoot me down
 
solent clown said:
I gathered that, just wondered why it is all one piece. It would be very simple to add a vertical loop between the upper and lower guardrail tensioners to acheive the tightness required.
I am not being smart, just curious, I am no expert on this matter at all. So please feel free to shoot me down
Click to expand...

I see what you mean. If you want to cut it in a hurry the fewer strands the better. You could get enough tension with a variation of the "lorry hitch", leaving only one or two strands to cut.
 
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