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Author Topic: gog irons on a roller stern tug  (Read 297 times)

essexbill

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gog irons on a roller stern tug
« on: June 24, 2018, 12:55:54 PM »

Hello.


I have spent hours looking at photos on line and in books, but I need some help from the Mayhem Folks.


I have a roller stern tug, I know I need a form of gog iron, I have seen photos of what looks like two hydraulic pins coming up at angle.


Other photos show the Karm fork.


I interested in seeing what others have done or suggestions.
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Umi_Ryuzuki

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Re: gog irons on a roller stern tug
« Reply #1 on: June 24, 2018, 08:55:39 PM »

Most modelers that use them either build them in the raised position, on either side of the roller or bulwark, or
they scratch build a powered lift system using either geared motors, or a combination if gear drives and push cables.

Leen Boer is a master at this.  8)
https://www.youtube.com/watch?v=RFQPL0qV7W0
 
https://www.youtube.com/watch?v=pwL9AVeQuh0

https://www.youtube.com/watch?v=6H78gEqnEa8
 
Tom Boere's build up of towing pins.
There is a spiral slot on the side of his tube that makes the pins rotate as they rise and fall.
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Brian60

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Re: gog irons on a roller stern tug
« Reply #2 on: June 25, 2018, 01:02:34 PM »

Karm forks and shark jaws do the same job - trap the anchor chain/cable during recovery or deployment of anchors. The pins raise from the deck to guide said chain or cable during operations, then lower together or individually during operation dependent on what they are trying to achieve.


I have never seen them in use during towing operations either rig moves or other surface craft. If its surface craft I am pretty sure they rely on raised pins atop the cargo rails, if its rig moving, the sheer weight of the tow cable is beneath the surface in a long loop, using the active heave compensation of the winch (usually of the waterfall variety) to keep it in operating boundaries.


See if I can illustrate, firt pic shows the restraints on top of the cargo rails, they stop the tow rope going any further forward (alledgedly)


the second one is sylised towing operation. the space between ship and rig can be 500metres or more, no less than 200metres. The tow cable hangs down (red) below sea surface (blue) in a loop, effectively more than doubling the distance between tow ship and rig, so the weight of the cable really doesn't need the restraint of gog ropes.

essexbill

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Re: gog irons on a roller stern tug
« Reply #3 on: June 25, 2018, 04:48:29 PM »

Wow Umi.
Those working ones of Toms are a real masterpiece.


Many thanks for your comments Brian, the photo gives me some ideas, the picture and description for long line towing I had seen a similar explanation but it is always good to have things confirmed.
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