Well....if you towed straight off the hook and the job got too far off track and got alongside you a bit, theres a real danger of capsizing the tug...or 'girting' as its sometimes called.
The gog eye is length of cable with an eye on, or a fitting on deck that effectively moves the point of effort much further back, hence removing most of the capsize risk. Modern towing practice uses wahst called 'indirect towing' to use the boat itself as a sort of paravane to enhance the stated bollard pull of the tug, towing the the twoed vessel left or right of her line making much more versatile control.
The point at which shes 'gogged down' is very important as if done too far aft of the turning point of the rudders, the tug will lose some of her own steerage, a movable gog would mean that she could adjust the length of cable with gog eye on the end, giving the best of both worlds. A portable gog would would be either in position... or not!
I think Conqueror may wekk have whats called 'Karm Forks' though, these are raised up from the deck when required, or retracted when not......any help?