dom
Well-Known Member
It avoids the requirement to have the preventer done up bolt tight.
Cimbing ropes for halyards?
- Thread starter lampshuk
- Start date
It avoids the requirement to have the preventer done up bolt tight.
jerrytug
N/A
Why wouldn't you want it bar tight and rigid, set up by swigging the mainsheet? Preventers are long, I have seen a (heavy-ish gaff) boom accidentally gybe as the preventer stretched, and the stretchy preventer contracted after the boom gybed, flicking it over the other way like a Roman seige engine. Must have hurt the shrouds or chainplate fastenings, it made it shocking noise.
Yes the helmsman's mistake, but:
* Rigid non-stretch rope and it could not have happened. *
lustyd
Well-Known Member
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By all means go to the store. Browse the precious things of the shop. Google any and all deals before you buy, it's likely they are pretend offers to make you think you have a good deal when you don't. Best case, you pay retail price. Worst case, you buy cheap **** thinking it's better quality than it is. The reality is that Amazon almost always beat them on price for the same item but you don't get that same retail shopping high
lustyd
Well-Known Member
Trouble is, the boat may still have gybed just that the boom wouldn't have swung across the boat in the process. This would possibly still lead to injury as the boat goes all crazy instead of just the sail. Another alternative ending is that the non stretch rope does its thing and the deck fitting fails due to the excess stress, rips out it's bolts and slaps some unwitting crew in the face with a cleat. Ideally a preventer is just to stop the boom swinging about due to wave motion rather than to actually prevent a gybe - that being the job of the helmsman.
dom
Well-Known Member
Goodness I hadn't heard the term swigging before, but having looked it up what a great word! As for the accidental gybe you describe, that's a good point and if the preventer is attached well forward it would probably not be such a good idea to use a stretchy line. When push comes to shove I would say that the best two options are either a specialist damped boom preventer, or the swigged (?) tight non-stretch preventer you describe.
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jerrytug
N/A
Very true, good points.
You can attach the preventer to the windlass or the stemhead fitting, furthest forward gets the best angle, and bring it back to a belaying point or winch within reach of the helmsman, using a snatchblock, or snap shackle and turning block, for convenience in the event of a *deliberate* gybe.
An accidental gybe on my new old boat could snap the boom I reckon. sorry for the digressions anyway.
oldbilbo
...
I like it.... ( In-joke )
Yottie boom brakes are expensive. Much the same 'strong frictional, slowed motion' effect may be achieved by use of a climbing/abseiling 'Figure-of-8 descendeur' of this type...
This is not a new idea on performance boats. Americans use it, and so do top French racer crews. Here is the item in use....
....with a singled, not a doubled, line.
jerrytug
N/A
Good point about using climbing gear. I have strugged to find good places to tie the ends of a boom-brake line on deck. Too far aft, it fights the sail or topping lift , trying to drag the boom down, but too far forward it does SFA because the angle is wrong. And there won't be any thing to tie it on anyway. I bet those French racers have had massive cleats, or probably deck turning blocks, specially put in, with at least one end led back to the cockpit. Flash so and so's.
temptress
Well-Known Member
to stretchy by far and also not usually able o stand up to use onboard ate use profiles are different. I speak from experience here as I one many moons ago had access to a large amount of climbing rope o all sorts of sizes so I experimented and concluded that I was better off using rope designed for the job,.
JumbleDuck
Well-Known Member
Thanks. They do deform plastically though - that's why the number of falls is limited. Each one puts a bit more permanent extension in the rope.
dom
Well-Known Member
I wonder what would happen if one used such a rope as a halyard: would it find a maximum extension length, or would the core keep on stretching until all of the pressure was borne by the braid which then snapped?
KellysEye
Well-Known Member
I used a halyard for a climbing rope, it doesn't stretch.
jimi
Well-Known Member
few years ago I was foolish enough to use an old climbing rope as a genoa sheet. It snapped half way across Lyme Bay in a F5, presumably because all the elasticity had been removed by being under continuous tension. Conversely using a non stretch rope as a climbing rope has a high probability of causing serious injury if one falls as all the energy will be absorbed by the falling climber rather than by elastic deformation of rope. Simplistically a longer fall on a climbing rope is "softer" than a short fall with a small amount of rope between the climber and the belayer. I used to practise falling off at the indoor climbing wall .. and big falls are definitely more comfortable than short ones,providing nothing is in the way and there's no abrupt stop on the floor.
TheEcho
Well-Known Member
The fall test for climbing ropes makes the rope break after multiple large falls in quick succession. If you gave the rope a day off to recover between such falls, it would take more falls before breaking - so it recovers and shrinks a bit if you let it. A climbing rope that is on its way out will feel stiff to the touch and be awkward to knot. Before it snaps there will probably be flat spots indicating core damage which you can feel if you run your hands through the rope. The core and sheath can slip a bit in relation to each other,not a problem, but I have never heard of one stretching more than the other.
alteredoutlook
Well-Known Member
Don't fall on it then; it might snap!
dom
Well-Known Member
Interesting; I've seen climbers at my local gym doing practice falls and you're right, in fact one can visibly see the absence of a snatch stop. As an aside I think climbers are extraordinarily fit, one of them shot up my mast with some ascender duberrys in what seemed like about 30s! He only wanted to have a look around!!
alteredoutlook
Well-Known Member
Do a Google search on 'caving supplies' and you will find several caving shops on line selling you static ropes. Prices are around £1/metre - considerably cheaper than yottie rope. Searching the manufacturer's website will give you the rope properties and comparison with yottie stuff will show they are probably similar.
Caving rope doesn't generally come bigger than 11mm in diameter (11mm is enough to climb on and the thicker it is the heavier it is - especially when wet - have you tried hauling 150metres plus of wet rope through caves???)
Another thought is that caving rope doesn't come in the same number of colour combinations as yottie stuff (.....and after a few caving trips it all becomes brown!).
Another is that splicing can be difficult - but then again some of the modern yottie stuff can be.
If I had a smallish boat and was on a budget I'd seriously consider caving rope. But like all rope - consider its handling ability what you are using it for.
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TimBennet
Well-Known Member
All depends on the fall factor - a 100 foot fall on 100 foot of rope is the same as a 2 foot fall on 2 foot of rope: Both are Fall Factor 1.
The most you can have is Fall Factor 2 when climbing, and that is if you fall while lead climbing and have no gear placed. For instance you could have lead out 10 foot from a mid stance (not the ground) and have a 20 foot fall on the 10 foot of rope in use. Same loads as if you lead out 100 foot and have a 200 foot fall.
If you go on the DMM website they have lots of video of different fall factors being arrested by both dynamic and non dynamic (static) ropes and slings. The most static type of slings are made of Dyneema (Spectra) and you can see that a 80kg person will break a 2.2 kN (2 ton) sling with a Fall Factor 2 drop of only a couple of feet. It's put a stop to people using them as 'cowstails' thinking that Dyneema is 'strong'. But strong is not all there is to it.
Even with leading on a climbing wall, you can not get Fall Factors 2 as you will hit the ground as there are no (precious few) intermediate stances. As you go up the wall the Fall Factors rapidly decrease. On the mainwall at Kendal, if you were 3/4 the way up the at 20 metres and fell whilst try to clip a bolt above your head, you would have 20 metres of rope out plus 2 metres of slack trying to clip, so 22 metres of rope in use and you would fall the metre above the previous bolt (X2 plus the slack) which is a 4 metre 'whipper'. Divide 4 metres by the 22 metres of rope and you have a Fall Factor of less than .2 (dramatic but hardly testing the system and almost unnoticeable on your waist and thights).
The other factor which determines the load actually experienced by the climber, rather than absorbed by the system, is the thickness and make up of the rope. All residual loads are now quoted for every rope. Thinner ropes are usually more gentle but more prone to sharp edge cutting and stone fall, whereas thicker beginners ropes are more durable, tough but less shock absorbing.
jimi
Well-Known Member
I did prefix my comments with "simplistically" as the intention was to explain different rope characteristics not provide a detailed technical explanation of climbing falls!
.. and you are not necessarily correct! You can have higher than a 2 fall factor if someone falls directly onto the belay but the belayer has gathered in some slack, or if he had let some slack go then that would have decreased it to less than 2. But thats a completely separate discussion, probably more suited to a climbing forum.
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TheEcho
Well-Known Member
Ascending a rope is about technique more than fitness. I have tried ascending a free hanging rope and was agonisingly slow because the sit harness kept positioning me in a sitting position with legs out to the side so it was hard to make upwards progress. With some more practice I am told you can keep yourself more vertical and put the load on the leg muscles so you are effectively going up a staircase where you choose the height of each step, but it is in some sense easier than a staircase because you push down with both legs at once rather than one at a time! Having a mast there helps with stability compared to free hanging.
People always assume climbers have strong arms - yes, top climbers have very strong arms, but at a regular level someone with strong arms who uses them all the time will climb worse than someone with arms like noodles who has learned to use their legs instead.