Do I need Turnbuckles

[sarabande]

can I make an urgent plea on behalf of the Federation of Mistreated Ropes and Lanyards ?

If you use a plain small shackle where the pin is the same or less diameter than the line, the line will be reduced in diameter (and thus working load) when under strain.

In very general terms, a rope (cable, sheet or line) should be led through a block, the diameter of whose sheave is a minimum of 5 times the diameter of the rope.

Now there may be space to argue that modern ropes allow a different rule of thumb, but I have had for many many years a eufroe (or jungfrau) from a shipwreck off Beachy Head. In the pic, I have put a standard cotton reel to show how the lignum vitae has been bored and eased to allow the cordage to pass easily through 180 degrees without being nipped and losing strength.

I'd love to experiment with a load cell, some dyneema, and a few shackles, and see what happens when multiple turns are put round a shackle pin of a similar dia as the rope, and then see what happens when a proper turning radius is used.

It seems to me that a prudent sailor would use a thimble or a large shackle to mitigate against an obvious point of potential failure.

 

[sarabande]

Messrs Colligo, who know a thing or two about rope rigging, have a hightech, and probably expensive solution. Yet it illustrates how they make the dyneema turn gently over a large radius of curvature.


Compare and contrast it with the pic which Twister Ken has used to show a shackle pin being used to torture the rope.

 

[prv]

I have had for many many years a eufroe (or jungfrau) from a shipwreck off Beachy Head.

That's a deadeye, surely?

I understand a euphroe to be a rectangle or flat triangle of wood, essentially something much longer than it is wide or thick, and used either to suspend an awning (especially on warships) or to combine the sheets of a junk sail.

</terminology_pedant>

Pete

 

[wklein]

If the shrouds are 5mm there will be about an 8mm hole for the turnbuckle, if you use a 8mm shackle and 5 complete passes of 3mm dyneema, in a perfect world that gives you a breaking strength of 9T. Compare this to 2T for the wire then that leaves you with much more than enough strength once the tight turn is taken into consideration.

 

[sarabande]

I've always used the term for that piece of kit and other similar ones afloat.

However, I have just looked it up in my Admiralty Manual Of Seamanship (1937 !!!) and there is a diagram using the term "euphroe" as you suggest. My Lords Commissioners do, however , use the word in connection with a "whip" (of 2 and 1/4" wire ), so it may be the word has been extended.


Searching further through the web, PRV, I am convinced you are right, and my use of the word has been erroneous for over 50 years ! I blame CPO Blazer (long departed) and to whom I owe many blisters for seizing and parcelling

 

[jwilson]

the value of your answer hinges upon your definition of small

Dylan

About the size of a Liberty/Minstrel or smaller. Small bottlescrews are horribly easy to bend. By the time you get to a heavyish displacement or beamy 26-footer you might think about bottlescrews as better, but even then lashings can be strong enough, as long as you have big enough and smooth enough fittings on wire and hul to tie them round. As others have said some very large boats have used bits of varying sizes and types of string to hold up the rig.

The "fashion" for bottlescrews is racing-derived - as it makes it easier to adjust tensions more precisely.

 

[Yantlet]

Seems to me much is being made of a simple problem ,if indeed there is a problem!
Can't say I see many sailing craft using rope other than for the forestay down my way.

 

[dylanwinter]

ahh

Seems to me much is being made of a simple problem ,if indeed there is a problem!
Can't say I see many sailing craft using rope other than for the forestay down my way.

ahh....is glory of sailing.

It offers simple problems and simple solutions

it is so unlike realy life which offers complex problems that seldom have good solutions

I am going to start with shackles and string

Dylan

 

[VicS]

ahh....is glory of sailing.

It offers simple problems and simple solutions

it is so unlike realy life which offers complex problems that seldom have good solutions

I am going to start with shackles and string

Dylan

What fiddle-arsed way of doing things compare with simple bottle screws!

If they come untied like my shoelaces always do you'll soon be at the bottle screw counter in the nearest Chandlery

Thought of trying Velcro ?

 

[Gwylan]

Posh string

what string

and around what

is a shackle good enough

what should the shackle be made of.

I fancy two bits of string with separate knots.

I bit of string eight times up and down

or

two bits of string four times up and down

Dylan

Google Ropeloft and ask them.
Seems to know what they are doing and do not use the phone book to prepare their prices.
Done some good work for us in the past and hopefully in the future.

 

[lw395]

Could you use a dinghy-style pair of plates with holes in at 1/2 inch intervals? Then just tension the rig with the forestay?
Or do you need to apply tension using these lashings?

I think the lashings will be fine, provided they are not chafed by anything. But you may get some corrosion on the metal parts due to being wet and fretted by the lashing?

 

[dylanwinter]

I like the simplicity of rope.

Could you use a dinghy-style pair of plates with holes in at 1/2 inch intervals? Then just tension the rig with the forestay?
Or do you need to apply tension using these lashings?

I think the lashings will be fine, provided they are not chafed by anything. But you may get some corrosion on the metal parts due to being wet and fretted by the lashing?

I like the simplicty of rope

I can see when it is getting tired

Aesthetically I think I prefer it

when dropping the mast it seems much better than bendable turnbuckles

it is a gunter rig so it will not be running under much tension _ I assume

Dylan



Dylan

 

[maxcampbell]

I use shackles & string - I know I should be kinder to my string, and if I find something suitable I will use it, but as for the string, let me put in a plea for matt polyester - it holds knots superbly well.