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.
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Topic: gog irons on a roller stern tug (Read 136 times)