It appears that the majority of members on here have never done 'the real thing' in terms of towage, so here we go with terms used in the industry to assist you! Feel free to add others as you see fit.
Bitts - Posts, heavily constructed, used to secure mooring or towing lines.
Bollards - as above but mounted double.
Bridle - Two short lengths of wire or chain formed as an inverted 'Y' and used as the connection between the tug and the tow.
Fairlead - Fittuing in the bulwarks of vessels to act as a guide for wire and rope and which prevents chafing.
Girding - When a tug capsizes during towing. Occurs when the tow is abeam or at 90 degrees to the tug's centreline and the 'capsize moment' happens. Also known as 'Girting'.
Gog / Gob rope - Used in towing and controls the position of the main tow rope against girding. In some parts of the UK it is known also as a gob rope, a bridle rope or a stop rope.
Molgoggers - These are also known, in some parts, as Norman pins or Stop pins. They are steel pins or rollers that are erected in a tugs bulwarks at the after end to guide the towline and preventing it from passing ahead of the beam.
Pendant / Pennant - A short length of steel wire rope / man made fibre rope attached to a main tow line.
Spring - Part of a towline (usually only used on coastal, sea and deep sea tows) which introduces an elasticity in the whole length, and so reduces the loads used in towing. I never saw these used offshore or when towing rigs - but they were always used on the deep sea and coastal tugs I was on.
Tow beams - Also called Tow Bows in some parts of the UK - are protective bars running across the working deck which allow the tow to move without getting caught or 'snagged'.
Towline - The rope or wire that connects the tug to the tow!
We can do parts of a tug at a later date - but some of the terms I have used....oh dear!
Jonty