Catenary and coiled rope - for dummies.

  • #1

Main Question or Discussion Point

situation: boat moored at the dock

fact (so to say) 1 - why the longer the rope and his catenary shape the stronger it will become? assuming it is true.

fact 2 - why a man can keep a heavy boat stopped with just a coiled rope in the mooring?

ps..if theres a better place to put the thread please advise...
 

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Answers and Replies

  • #2
is it just me? i don't understand the phrasing no matter how many times i re-read it.



a boat can be moored w/ a rope because the boat is supported by the water.. the rope and anchor system is a positional fixer, working against the current and wind. i think, is that what you're asking?

moored boats are ones at anchor, as seen in a bay, w/ those bouys. At a dock, the boat is slipped, or "tied up".

Sometimes, care must be taken because if the dock is fixed and doesn't rise/fall with the tide, the tide will go out and the boat is going to be suspended in the air. Well, it ususally just tears the cleats out from the dock and smashes about on stuff.

i boat a lot, and so I replied, hopefully you can clarify what you're asking, i'd like to help if possible.
 
  • #3
i wil try to refrase it later.

But my main concern is about the geometry of the rope which will result in exploring is strength.

1- catenary

2- the way the rope is coiled aloes a single man hold a heavy boat.

I hope this clarifies
 
  • #4
Well, i'm not sure i understand what you're asking about, but that's ok, just try to rephrase it later on..

I can tell you in general, that caternary curves, aka cat curves, are employed in sails and tents because they distribute stress more effectively than other shapes. Search the website backpackinglight.com for info catenary curves and you'll find more than you'd ever want to know about them. Those people use them all the time for making tarp-tents and have great tutorials for some Do-it-yourself action.

Rope design, is a fairly complicated field. I'd check out "rope safety mountain climbing" or similar google search.. this doesn't have much to do w/ cat curves tho, .. unless I'm missing something. At a dock, the ropes are slack and appear catenary if gravity is the dominant force on them. When they're taught, it's because wind/current/motor is acting upon them.

Coiling rope, like coiling an electrical cord, has a technique to it to 1) not damage the rope components and 2)no tangles on deployment. I do not see how a coiled rope allows a single man to hold a heavy boat. What specifically does coiling it have to do with it?
 
  • #5
ok! thanks a lot for your help!

i will do better than refrase it, i will draw something to express what i talking about.

i wil now check the link you kindly propose.
 
  • #6
Jasongreat
I do not see how a coiled rope allows a single man to hold a heavy boat. What specifically does coiling it have to do with it?

Coiling a rope around something, such as a pole, creates more friction area, allowing a small man to to hold a large load. Each time around adds a mechanical advantage, kind of like going threw a bunch of pullies. If that is the type of coiling being discussed?
 
  • #7
Coiling a rope around something, such as a pole, creates more friction area, allowing a small man to to hold a large load. Each time around adds a mechanical advantage, kind of like going threw a bunch of pullies. If that is the type of coiling being discussed?
That makes sense! and yes it is the type of coiling being discussed.

But let me ask ...
The catenary curve described by the rope will "strengthen the system"?
Or bigger the distance between boat and pole stronger is the effect?
Can we take maximise ropes strength with larger distance?

Anyway Jason, thank you for your reply!
 

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