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Old 25 August 2013, 08:17   #1
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What thickness of rope to retrieve a trailer and RIB?

The approach is obscured to the slipway I launch / retrieve from. I plan to use a pulley arrangement and heave out using my car at a right angle. What thickness of rope would you suggest for this?
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Old 25 August 2013, 08:32   #2
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have used 12mm braid on braid, breaking strain 3T.

That could be over kill.

On the other hand if the trailer gets stuck (rock under wheel) would your car have enough pull to break the rope? Flying rope is never good... If trailer was already part way up slip rolling trailer back towards passers by is also not good.
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Old 25 August 2013, 08:33   #3
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10mm multi would work well. or you could try one of those small detachable from tow bar winches.
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Old 25 August 2013, 10:31   #4
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Don't forget to make sure the pulley is up to muster as well!!

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Old 25 August 2013, 11:53   #5
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I like to use 12mm min for anything heavy I might have to use my hands to handle - more to grip and less risk of cutting into my hand. Will ultimately depends on the total weight you're handling.
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Old 25 August 2013, 12:01   #6
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Hi jlang

Sounds like hauling a boat up the slip that way..could be a waiting for an accident to happen.

When I was in the same situation with my heavy harshell boat.. I fixed an electric winch to the trailer drawbar. The winch was on a plate that I just slotted over a couple of pins welded to the trailer. Very easy to attach or remove.

Attach the end of the winch to where you are thinking of attaching the pulley.. winch to there and chock off the trailer wheels so it cant run backwards. Re attach to your car towbar and winch to there..hook up and drive off safely.

Alway keep a chock at hand ..so if you think something is not going right..you can chock of the front jockey wheel ..instantly. I even replaced the wire with a winch tape as I didnt like to think what would happen if the wire broke.

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Old 25 August 2013, 12:32   #7
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Thanks chaps, sounds like 12mm will be easier on the hands and give a bit of margin for error.

Gurnard, neat solution! But what's unsafe about using a pulley, provided it's up to muster as CJL suggested?
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Old 25 August 2013, 12:45   #8
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Perhaps its just me being over cautious Jlanng.

I launch and recover on my own..so would always want to be beside the trailer and not sitting in the car where if something goes wrong..I have no control.

I guess if you are confident the rope wont break..the pulley wont break .. where the pulley is attached wont give way and that nothing else will give.. then its safe to do it your suggested way.

How do the other folks do it at this slipway ?.. they will be in a far better position to advise than people who can only surmise the situation...they will be able to advise on the thickness of rope required too.
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Old 25 August 2013, 12:53   #9
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You need to make sure the pulley or block you are using is at least rated for three times the load you know is going into it as when you deflect a line through 90 degree you are increasing the load by up to 75%.

You also need to consider what you are attaching the block to and what with, this can be the weak link!!

The diameter of the rope you are using depends on what the material of the rope is s all the different materials have different swl.

If to are using a polyester braid on braid then I would use min 12mm this has a rough swl of 2500 kgs, but does have a fair amount of stretch / creep in it so be prepared for the rope to have some give it in.

Also if you tie a knot in the rope this will weaken the rope as knots are not good for rope, in an ideal world all loops should be spliced into the rope...

Hope this is helpful.
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Old 25 August 2013, 13:02   #10
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on trips away we used to get our club fishing boats off remote beaches with a pulley and rope and it worked fine. Pulley attached to ball hitch of one car on grass at top of beach, rope from another car thru pulley at about 90 degrees to boat on beach- From personal experience of seeing one break and do a fair amount of damage make sure the rope or whatever you hang the pulley on is strong enough. The rope on this one that someone had made up snapped and pulley flew thru the air until....well never mind until what Depending on the angle at the pulley there can be a considerable load on it.
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Old 26 August 2013, 01:16   #11
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Another thing you may like to consider is type of rope - the more it stretches, the more it'll fly back if it were to snap. I had a rope break while trying to pull a trailer out of soft sand and it flew back with enough force to take the mudguard off the trailer and break it in two. Thank god it didn't hit anybody. After that I got a dyneema winch rope, the point being that although it's massively stronger than needed, it's very low stretch means it doesn't have enough stored energy in it to fly around in the same way if something does let go -which is why it's used on winches. Of course the low stretch also means that if the trailer suddenly jams on a rock or something things will tighten up fast but assuming you're going slowly anywhere things aren't obviously clear that should be manageable - again, better than a big bungy loading up behind you
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Old 26 August 2013, 02:28   #12
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Depending on the length you need you could consider a certified webbing sling, they're readily available in 3000kg SWL and up to 10m length.
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Old 26 August 2013, 02:54   #13
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What ever method you use be careful!
If it is a public slip, and other people are around, you cannot vouch for what they do, and they could get in harms way.

I like the method proposed by Gurnard, but you can also get tow hitch mounted winches these days. A couple of big heavy duty connectors (anderson connectors IIRC) and put thje winch on the tow hitch, connect it up, and pull away. you could google the winches I think.

I would definately think about going for dyneema, Spectra rope, as it has very high strength and very little strech meaning it does not recoil very much if at all.

I have 12mm spectra on a winch, and it has a MBL of over 10 tonnes.

Also consider using a heavy winch blanket or similar whatever method you use, as it helps to reduce whiplash.
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Old 26 August 2013, 03:49   #14
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Try Marlow ropes: http://www.marlowropes.com/winch-lin...coverline.html or similar from their range.

I see no problems with the concept of a right angled pull through a pulley block. Just make sure all the attachments are up to standard. For extra security if you have a braked trailer tie a second smaller rope on to the brake safety cable on the trailer and have an assistant keep this from getting slack, if the main winch line fails the trailer will roll back and the trailer brake will be activated.

It is also a useful way to recover a boat where the slip is steep or slippery and you can't get traction on it. Keep your vehicle on good flatter ground and use a block and tackle to get the pull to where you need it.
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Old 26 August 2013, 05:17   #15
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Quote:
Originally Posted by Impulse View Post
I see no problems with the concept of a right angled pull through a pulley block. .

Yup..I do agree ..there is no problem doing it.. after all .. cranes have pulleys on the end of their jibs and lift huge weights without a problem..its the same idea.


IMO ..The biggest problem is not really if the rope breaks .. because if it does, it will fly back in a straight line.. and if it was going to cause damage..it would be to the car pulling the rope..or to the boat and trailer ..where hopefully no one is standing ready to apply the brake or a chock under the wheels to save the boat rolling back down the slipway. They could be injured by flying rope if they were.


However if the pully broke ..or its mounting .. then anything or anyone in the area of the 90 degree pull will probably be damaged or ..if a person .. injured or killed. Think of the strong rope for extra safety .. as a huge catapult..powered by the weight of the boat trundling down the slip.

No matter how careful we are..accidents do happen. Thats why we are taught to do risk assesments..to reduce risks. Putting a pulley in the system and pulling at 90 degrees greatly increases the area of risk. Pulling in a straight line keeps the risk to a minimum and thats what I try to do.

The pulley at 90 degrees also increases the risk of the rope breaking as more force is required.


Using heavy rope..and non stretch winch rope..all reduce the risk of accidents happening if things do go wrong..so that is good.

Can you pull the boat up by a 180 degree pulley pull..ie drive your car down the slipway to pull the boat up. That will reduce the area where damage can occur to a straight line again.


Its also good to have a back up plan..in case something does go wrong.. as someone suggested..a secondary rope to apply the brake..or a blanket over the winch rope as it will reduce the risk of it flying back at speed.


As I first mention.. if nothing gives way.. then it is perfectly safe way to recover the boat.

If something goes wrong ..... I wonder if insurance will foot any bills ?
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Old 26 August 2013, 18:29   #16
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Yup..I do agree ..there is no problem doing it.. after all .. cranes have pulleys on the end of their jibs and lift huge weights without a problem..its the same idea.
mmm... cranes go through huge amounts of testing (both at design stage and regularly throughout their life). So I am not sure it is the same.

Having seen a metal cable go "pop"* as a tractor tried to pull a pontoon up a beach I wouldn't assume it will go straight, or that low stretch = almost no recoil.

If the general public are in the vicinity I would say its a definite no-no. They are incredibly stupid, and walk between car and trailer or behind trailers on a rope nonchalantly oblivious to the risk they are at. IF you confuse them with a 90 deg bend and a pulley they are probably more likely to congregate to see what you are doing.


* Actually it was WAY louder than 'pop'.
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Old 27 August 2013, 02:37   #17
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Where are you intending launching/recovering from?
Have you looked at the methods used by other people?
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Old 27 August 2013, 03:10   #18
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mmm... cranes go through huge amounts of testing (both at design stage and regularly throughout their life). So I am not sure it is the same.

Having seen a metal cable go "pop"* as a tractor tried to pull a pontoon up a beach I wouldn't assume it will go straight, or that low stretch = almost no recoil.

If the general public are in the vicinity I would say its a definite no-no. They are incredibly stupid, and walk between car and trailer or behind trailers on a rope nonchalantly oblivious to the risk they are at. IF you confuse them with a 90 deg bend and a pulley they are probably more likely to congregate to see what you are doing.


* Actually it was WAY louder than 'pop'.
+1
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Old 27 August 2013, 03:19   #19
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Unless this slipway was at the bottom of my garden, I'd be looking to use a different one......
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Old 27 August 2013, 04:35   #20
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No advice on the recovery, but the safety angle: The general public, in fact, everyone I've ever seen, are incredibly unaware of winching risks. I have to do long line launch and recovery regularly and people in the vicinity ALWAYS try to step over the line when it's under load. That's a line that's bowstring taut with a ton and a half of boat and trailer on the end. Right below their nuts. I explain the risks and they say that I shouldn't be doing something as dangerous as that!
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