After having the sail cleaned over a year ago I am finally attempting to re-install it onto Cay Cat for our Fall sailing season. I am perplexed by the part of the gaff halyard that slides on the mast. It has a three inch long pin with an eye on it that appears that it should be pointing upward. Is this where the main sheet connects to the sail and gaff halyard? It doesn't look robust enough but perhaps the gaff sheet takes most of the true load?
The 1/4" pin with eye is where you connect the throat halyard. The main sheet connects to a bail about mid-point on the boom or at the end of the boom depending what set-up you have. Look up Catboat Guide and Sailing Manual on goggle and this should answer most of your questions.
ROGER