I hadn't really thought before about such a thing as a 'one sided floating drydock', surely the objective of two sides is for capacity to flood down or raise while keeping on an even keel by having tanks in the two sides, whilst also supporting cranes etc.
But a pontoon such as Austin's requiring side access would also need to keep level, so was the water capacity for flooding entirely in the bottom section? If so, then that section would presumably need to be deeper than in a floating drydock with 2 sides, and that would work against the available draught for getting a ship on or off (unless it was in a deep hole!!).
Answers on 2 sides (or maybe 1) please .....