Going back to the portable gogeye, Blazing Penguin is right if only a conventional straight tug is considered but the Conqueror wasn't. The reason why you may have a portable gogeye shown in plan but not in elevation is simply because it was portable and thus wasn't always there!
The 'Conk' as she was known, was an anchor-handling-tug-supply-vessel (AHTS) which sometimes was used for towing/anchor-handling. When used as a supply vessel, the presence of a large forged-steel gogeye (think of an oval fairlead about 3' high) used only when towing etc. and planted in the centre of the deck, would seriously interfere with cargo stowing operations. Thus the gogeye was made to be unbolted (portable) such that it could be moved away from the cargo deck and stowed out of the way. When in use, the tow wire was run through the gogeye. Maersk vessels often used a similar system.
Cement (Barytes) tanks were sealed silos used for the carriage of powder cargos and discharged by compressed air. Liquid mud (cement) if carried, was discharged by scroll pumps. In powder form the barytes was mixed originally with diesel (later on with water when environmental concerns were addressed). The mud was used in drilling operations partly to lubricate/cool the drill bit and partly to fill the well behind/above the drill bit and counterbalance the pressure of any oil entering the well. Calculating the density of the mud was a bit of a black art and performed by so-called 'mud engineers'; we real engineers often took offence at the term and put them in the same category as Drillers and similar riff-raff.
Several of the early Seaforth vessels did have A-frames at the stern but they were all later removed as being of no real benefit.
Hope this clarifies things.
Regards
BarryM