Hi Ibwet, yes I would have thought being towed rather than towing.
I have no argument with this other than to mention that if you have the power and steerage, then a tug finds it most useful to have the centre of towing somewhere centre midships.
Anyway, I seem to recall it being called a Sampson post and whilst its is easily associative witha strong post and thus samson who was the strong man in the Bible, but I doubt it has any association.
Term: king post (maritime)
Definition: A strong vertical post used to support a ship's windlass and the heel of a ship's bowsprit. Also called a sampson post.
[Source: "Glossary." Wisconsin's Great Lakes Shipwrecks (http://www.wisconsinshipwrecks.org/)]
An important thing about this is that I believe for a rib you will not use the transom post other than to tie off the bitter end of the Tow rope with it having been taken through a "fairlead on the bow and made off low on the lower bow eye to keep the bow from dunking....
Dont get me wrong, you can call it what you like, I have no doubt that it is no more than the difference between Colour and color.
I seem to recall it being built into the Centre Backbone of Boat whatever they call it and thus it pins own a Bowsprit. so be careful if you add one that it can take the same strain...
The other important thing is that people involved in tow situations should be aware of hawsers breaking and decapitating people. In heavy seas where the period of the waves causes a jerking movement between tow boat and boat being towed (mainly in heavy displacement boats) versus the wave period, the strain on the tow line can be too much as in Jerk break with dangerous results. So dont worry what its called, you shouldnt have to use one in RIB.