guard wires

[emearg]

Just been on cruising lea lea utube channel and I noticed that instead of wire guard wires he has replaced them with rope, I thought this was a better idea than using wire because:-

1. It can be replace easy on a diy basis
2. In the event of man over board it could easily be untied to get casualty back on board. You could make your own system to suit you.
3. It would also be kinder to crew ...ever seen a wire rope bruise.
4. Perhaps not quite the same in loads bearing capacity but then it you require that amount then perhaps you should lose a few pounds

Does any body have any idea why I shouldn't replace mine with rope as I need to replace a stantion and this would make it easier for me.

........just thought............. it would chafe if you didn't have suitable stations to run it through ie it wouldn't work with hollow stations but it would work with solid stations.

Graeme.

 

[Nigel-in-Oxford]

I had rope on mine, but the surveyor said I should change them back to wire, no reason given.
However I have now removed my stanchions altogether as I have narrow walkways and I was always snagging on the things.

 

[Jaguar 25]

If you use Sta-Lok fittings you can do it yourself. I have recently done this and used releasable snap shackles (??) at the cockpit end in case of MOB.

Rope is OK if you use Dynema.

 

[jamesjermain]

Guard wires must be very strong and very tight. This simply cannot be achieved with rope unless you go down the Spectra/Dyneema route and even then I would worry about chafe. Wire guard wires need replacing at such infrequent intervals I don't see the need to have them made up professionally as a problem. Guard wires should always be secured and tensioned at one end by several turns of line which can be cut in an emergency or an easily released pelican hook with plenty of spare threat to adjust it.

One other thing with wire, plastic sleeved wire can corrode under the cover without you being aware.

 

[Georgio]

Guard wires must be very strong and very tight.

Hi James,
I agree they should be strong but I'm interested in why you believe they should be very tight, I'm not saying you are wrong I'm just interested in the reasons why.

I then to have mine a little loose, mostly because of "wobbly ladder syndrome" - It goes like this - the way to stop people falling off ladders is to make them wobbly because the user of the ladder holds on tighter and is less inclined to lead out too far, the ladder itself is no more of less safe but the risk of falling off is made more obvious to the user. I would rather people sailing on my boat hold onto the firmly bolted coach-roof handholds that are further inboard than the slightly wobbly guard wires, but the guard wires are still there to do their job if needed.

Be interested to know your and others thoughts on this.

Sorry thread drift.

 

[Deleted member 36384]

Don't assume that the reason the person falls off the ladder is because they were not holding on tight. You sound like an accountant who justifies buying cheap wobbly ladders.

 

[Rigger Mortice]

"wobbly ladder syndrome" .

That sounds like the idea that putting a hefty spike on steering wheels would improve the safety of drivers.

 

[Jaguar 25]

Guard wires must be very strong and very tight.

Keeping guard wires tight will put an unnecessarily high loading on the stanchions, which is undesirable. I would have thought that they needed to be firm but not tight.

Then again, some say that the main function of guard wires is to ensure that you fall in head first!

 

[mjcoon]

Guard wires must be very strong and very tight.

Keeping guard wires tight will put an unnecessarily high loading on the stanchions, which is undesirable. I would have thought that they needed to be firm but not tight.

Surely the guard wires change direction by only a small angle at each stanchion, so the static loading on them is not great. On the other hand if the load of someone falling against a guard wire is "undesirable" then better not to have any!

Mike.

 

[jamesjermain]

Well, one reason to have them very tight is that the ORC special regulations require it. I guess you just don't want the wire to drop 20cm when you lean on it

 

[jamesjermain]

The change of direction as the wire goes through a stanchion is very small and the load insignificant - also they are designed to take the load. Almost all the load is taken by pushpit/pulpit and these are certain stressed to take the loads

 

[Ludd]

I replaced my port side top gaurdwire three years ago with Dyneema. Worried about UV damage (I know it's supposed to be UV -resistant) I fixed a separate length exposed to the weather as a test. Tested that each year, with a 1 ton pull---no problems so far. As required, I will replace the rest with Dyneema.
I used a carter's knot to tension it.

 

[Georgio]

Don't assume that the reason the person falls off the ladder is because they were not holding on tight. You sound like an accountant who justifies buying cheap wobbly ladders.

Nope, people fall off ladders because they over stretch, thinking their ladder is secure, having a slightly wobbly ladder makes the risk of falling seem more apparent therefore users tend not to over stretch. I wish I could find the paper about this because it was a fascinating study into the way the brain works and assess risk.

 

[sarabande]

The change of direction as the wire goes through a stanchion is very small and the load insignificant - also they are designed to take the load. Almost all the load is taken by pushpit/pulpit and these are certain stressed to take the loads

I'd agree with JJ, and defer to his great experience, but there are some easy maths involved here.

A lifeline (guard wire) does bend in two directions. There is little change in the height from bow to stern, but the horizontal change to accommodate the vessel's beam can be as much 15degs (just from looking at one deck plan) .

The pic shows how much extra 'load' is placed upon a sling (and, by direct analogy, upon the pulpit and pushpit securing points) by having a wide angle under load.

View attachment 43169


Typically, for a very flat angle, the horizontal load is multiplied 6 times.


This load acts through the stanchion, which is why any very tight lifeline will impose severe leverage upon the stanchion, even to the extent of loosening adjacent ones out of the deck. We have all seen what happens when a non-sailing person tries to clamber on board by holding tight to the lifeline.

Lines must be pragmatically tight, otherwise one cannot rely on them for a firm hold while moving for'd and aft, or bracing feet against them while changing a sail, for instance.

 

[KellysEye]

>This load acts through the stanchion, which is why any very tight lifeline will impose severe leverage upon the stanchion, even to the extent of loosening adjacent ones out of the deck. We have all seen what happens when a non-sailing person tries to clamber on board by holding tight to the lifeline.

> any very tight lifeline will impose severe leverage upon the stanchion

It doesn't the wire goes through the stanchion and the load is taken by the pullpit and pushpit which are designed to take the load, as said earlier in the thread.

'even to the extent of loosening adjacent ones out of the deck' If that happen the boat has been badly/cheaply made.

>what happens when a non-sailing person tries to clamber on board by holding tight to the lifeline.

I've never seen anything happen, if it does refer to above.

 

[Deleted member 36384]

Nope, people fall off ladders because they over stretch ……

Yep, amongst other things, but you miss the point regarding guardrails. They are not just handholds, they also stop one from falling over if you fall against them and if correctly tensioned, contribute to supporting a MOB above the water if hanging by a lifeline.

Regarding wobbly ladders: if one always uses a wobbly ladder, then the perception of the likely hood of the risk happening reduces. It is driven by cognitive biasses which are mental models that we develop to risk, typically due to ignorance, complacency (familiarity) or even arrogance; it is a complex subject within Cognitive Psychology. The wobbly ladder is still dangerous but some may lean out and wobble with it, others may go up and down the ladder often moving it each time to do the required work, others may refuse to get on the ladder and some will climb the ladder and fall off because it wobbles. It is also why Volvo drivers at 30 mph cannot brake and stop the car without hitting a polystyrene wall, when others in 2CVs and open top sport cars can stop.

The problem of course is that the ladder is a tool to do a job. If the person understands the job and the risks associated with the job, then they will use a safe ladder, complete the job and usually will be more productive, thus loss will be avoided to the employee and employer and results are as expected.

Safety isn't rocket science, it is far more complex; trying to change humans who are generally predisposed to taking shortcuts by weighing up risks to always working in a safe manner takes considerable effort. A large part of my job involves this sort of stuff.

 

[ripvan1]

Guardrails, invention of the devil - jackstays and handholds concentrate the mind on staying on board - guardrails for us 6 + footers just the right height to trip over if hit broadsides by a rogue - don't ask how I know.

 

[Wooden Boat Fittings]

I agree entirely with Mr Winkle. I was in the process of replacing the lifelines' pelican hooks on Sanderling when I came to the conclusion that I'd be better off without any lifelines at all, and removed them. If you know there are none, you're more careful (just as you are if you know the ladder's wobbly). A pulpit's a useful thing to have if you're working up in the eyes (and also to have somewhere to lash a handed jib), and I suppose a pushpit is useful for hanging your barbecue on if nothing else... But lifelines encourage thoughtlessness and so become an unwanted source of danger. In my opinion, a jackstay down the centre of the deck with a clip-on harness always in use if you're outside the cockpit is the best way to go.

But if you insist on having lifelines, have them at a decent height, use un-plastic-coated wire, don't over-tighten them*, and put a pelican hook at each end for quick release if required.

Mike
* I once saw a fence-post pulled straight out of the ground when a new high-tension wire in the fence was being strained. Sarabande's vector diagram repays studying.

 

[John the kiwi]

First up, no reason not to use dyneema for guard wires. Size for size is about as strong and a lot friendlier.
I have spent an hour or two threaded through dyneema guard wires on the rail of a racing yacht.
Takes a while to become confident that something that is about as thick as the good old fashioned brown string is actually OK in the situation.
Just watch out for UV damage over a period of years...

As regards the thread drift on safety and perceptions thereof. What a fascinating subject this is!
When ABS braking was becoming more common, insurance companies noted that cars with ABS brakes were experiencing higher crash rates than those without. Seems that people do drive to perceived risk and believed ABS reduced the risk a lot more than it actually does.
On that basis replacing airbags with large visible spikes and removing seat belts so that instant death was the certain outcome of a crash would probably reduce the road toll dramatically!
Funny things people......

 

[johnphilip]

I'd agree with JJ, and defer to his great experience, but there are some easy maths involved here.

A lifeline (guard wire) does bend in two directions. There is little change in the height from bow to stern, but the horizontal change to accommodate the vessel's beam can be as much 15degs (just from looking at one deck plan) .

The pic shows how much extra 'load' is placed upon a sling (and, by direct analogy, upon the pulpit and pushpit securing points) by having a wide angle under load.

View attachment 43169


Typically, for a very flat angle, the horizontal load is multiplied 6 times.


This load acts through the stanchion, which is why any very tight lifeline will impose severe leverage upon the stanchion, even to the extent of loosening adjacent ones out of the deck. We have all seen what happens when a non-sailing person tries to clamber on board by holding tight to the lifeline.

Lines must be pragmatically tight, otherwise one cannot rely on them for a firm hold while moving for'd and aft, or bracing feet against them while changing a sail, for instance.

Either I am misunderstanding you or you are misreading your own diagram. The diagram is showing that to lift the one tonne load flat slings would be subject to a 6 tonne tension. Your lifeline would need a 6 tonne tension to exert a 1 tonne sideways force on the stanchion.
More realistically a more sensible 300KG tension in the guardwire would exert a 50 KG sideways force on the stanchion. If it cannot stand that then throw the stanchion away.