Author Topic: Strop over Towing Cable  (Read 4124 times)

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Aestus57

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Strop over Towing Cable
« on: May 23, 2009, 07:40:10 »
Hi Everyone,

As an ex Liverpudlian, I often used to watch the tugs at work in the River Mersey, usually the rope came straight off the towing hook, but occaisionally there was a strop over the rope and this was fixed to the aft cruciform bollard.

What is the reason for doing this? Can anyone of you experts enlighten a puzzled land lubber!  ???

Peter

Volker

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Re: Strop over Towing Cable
« Reply #1 on: May 23, 2009, 14:10:02 »
I think you are talking about a gog rope. It is used to control the movement of the main towline. With the gog rope the the towline is held down near the stern effectively moving the towing connection aft. This gives a better control over the tow and prevents the towline from being taken over the beam. It reduces the risk of capsizing. Pulling down the gog rope by hand is only possible with slack in the towline. Later tugger winches were used to do this with the towline under full load. For manoeuvering the gog rope has to be released.
Cheers, Volker

Aestus57

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Re: Strop over Towing Cable
« Reply #2 on: May 24, 2009, 00:01:15 »
 ;)  Many thanks Volker,  that has explained things nicely. :) :) :)

Todd

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Re: Strop over Towing Cable
« Reply #3 on: May 24, 2009, 05:58:05 »
A simple test for the use of a Gog-rope is to put a tack in the centre of a piece of wood (approx ratio 4:1).This will represent the centre of gravity. Float this in water,attach a cord to this and then pull on the cord.This will cause the `plank` to swivel and come broadside to the direction of the towing force and could cause the `plank` to capsize.Now pin the cord to the end of the `plank` and do the same,you will see that the `plank` will follow where-ever the force applied wants it to...thus avoiding the capsize motion. This Gog-rope was used mainly by the tug on the end of the ship where the ship was in effect the `towing` motion and the tug merely acting as a steering mechanism.When the ship needed to changed its Forward/Stern motion the Gog-rope was slacked/removed and the towed tug then became the towing tug.

This system was essential in closed dock systems such as that in Liverpool, where ships entered either bow or stern first and frequently in and out of the branch-layout of the docks.

Hope this helps.

Jim.
Capt Jim

Puffin

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Re: Strop over Towing Cable
« Reply #4 on: May 24, 2009, 07:33:26 »
A simple test for the use of a Gog-rope is to put a tack in the centre of a piece of wood (approx ratio 4:1).This will represent the centre of gravity. Float this in water,attach a cord to this and then pull on the cord.This will cause the `plank` to swivel and come broadside to the direction of the towing force and could cause the `plank` to capsize.Now pin the cord to the end of the `plank` and do the same,you will see that the `plank` will follow where-ever the force applied wants it to...thus avoiding the capsize motion. This Gog-rope was used mainly by the tug on the end of the ship where the ship was in effect the `towing` motion and the tug merely acting as a steering mechanism.When the ship needed to changed its Forward/Stern motion the Gog-rope was slacked/removed and the towed tug then became the towing tug.

This system was essential in closed dock systems such as that in Liverpool, where ships entered either bow or stern first and frequently in and out of the branch-layout of the docks.

Hope this helps.HI ALL ; Out here in the west coast we use towint pins . They used to be two wertical rolller pins on the stern in slots . Now they hydrolic raised into position .                     PUFFIN

Jim.

Todd

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Re: Strop over Towing Cable
« Reply #5 on: May 24, 2009, 07:55:19 »
A simple test for the use of a Gog-rope is to put a tack in the centre of a piece of wood (approx ratio 4:1).This will represent the centre of gravity. Float this in water,attach a cord to this and then pull on the cord.This will cause the `plank` to swivel and come broadside to the direction of the towing force and could cause the `plank` to capsize.Now pin the cord to the end of the `plank` and do the same,you will see that the `plank` will follow where-ever the force applied wants it to...thus avoiding the capsize motion. This Gog-rope was used mainly by the tug on the end of the ship where the ship was in effect the `towing` motion and the tug merely acting as a steering mechanism.When the ship needed to changed its Forward/Stern motion the Gog-rope was slacked/removed and the towed tug then became the towing tug.

This system was essential in closed dock systems such as that in Liverpool, where ships entered either bow or stern first and frequently in and out of the branch-layout of the docks.

hrHope this helps.HI ALL ; Out here in the west coast we use towint pins . They used to be two wertical rolller pins on the stern in slots . Now they hydrolic raised into position .                     PUFFIN



Puffin:that would work only when the lead of the towing gear is downward or horizontal  and not when leading upwards ie: to the deck of a high ship
Jim.
Capt Jim

Todd

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Re: Strop over Towing Cable
« Reply #6 on: May 24, 2009, 17:33:55 »

You will find an example of what can happen when the Gog-rope is not used or has `parted` on........,

<www.youtube.com/watch?v=Qljs9B55N84>

Jim
Capt Jim

Puffin

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Re: Strop over Towing Cable
« Reply #7 on: May 24, 2009, 21:58:23 »


hrHope this helps.HI ALL ; Out here in the west coast we use towint pins . They used to be two wertical rolller pins on the stern in slots . Now they hydrolic raised into position .                     PUFFIN



Puffin:that would work only when the lead of the towing gear is downward or horizontal  and not when leading upwards ie: to the deck of a high ship
Jim.
      HI JIM ;  Out here the pins on the stern have a top plate to stop the tow line coming out . The newer boats have a staple on the deck , and some of thje escort boats tow side ways . Ropes don't work with 80 tons ballard pull .                PUFFIN

Footski

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Re: Strop over Towing Cable
« Reply #8 on: May 25, 2009, 00:19:14 »

You will find an example of what can happen when the Gog-rope is not used or has `parted` on........,

<www.youtube.com/watch?v=Qljs9B55N84>

Jim

Jim,

The link does not work. Youtube says it is not correct..
Barry

Todd

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Re: Strop over Towing Cable
« Reply #9 on: May 25, 2009, 07:51:47 »
Barry I have just been over to YouTube and got the video OK.

The actual written heading is " Melbourne tug boat tips over towing ship and man overboard " maybe this will work.

Another thing I forgot to add that where tugs use a Gog-rope they are almost all Single-screw....In MSC,twin-screw, tugs the stern tug made fast from the bow when guiding in the canal.
With  all the variables available today the Gog-rope is an instrument of the past and I for one would have loved to have seen it happen a lot sooner. The Gog-rope on Alex tugs was usually an 8" manilla and could be a bugger to handle when no capstan/winch was fitted and it was all done manually. (In all weathers I might add...the rope had to be kept as dry as possible otherwise it went as hard as ,,,well you know what ! ! )

Jim
« Last Edit: May 25, 2009, 08:50:30 by Todd »
Capt Jim

Todd

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Re: Strop over Towing Cable
« Reply #10 on: May 25, 2009, 08:48:46 »
I have found this picture of the Gog-rope being used on the `Morpeth` (ex Cock Tug....Heath or West ?)
If the picture comes out OK you can see the wash of the tug bearing in mind that she is being drawn stern first through Hornby Lock,this is when the strain on the Gog-rope is greatest, her `sister` is the push-tug following her through.
Capt Jim

poll

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Re: Strop over Towing Cable
« Reply #11 on: May 26, 2009, 10:10:30 »
Hi Peter, This is a tug that works without a gogrope, It's the Carrousel Tug.  ( Tug on test )
Cheers

John.
« Last Edit: May 26, 2009, 10:14:06 by poll »