I would add a few thoughts about these 'side-mounted' cranes for operations' purposes. Usually these side mounted cargo gear are found on MultiPurpose vessels. Having a side-mounted cargo gear arrangement allows for maximum outreach of the cranes' booms for loading/discharging at docks with insufficient facilities.
To take it a step further, vessel's with side mounted cranes are usually considered Heavy Lifters and work two cranes in tandem to handle very heavy loads which further reduces the booms' outreach (wish I could draw a sketch for you all)! In order to counter for the immense heeling moments when swinging 400 tonnes in tandem lift of the side of a relatively small vessel (say 4,000 light ship displacement), very high capacity ballast pumps which work automatically with gyroscopic controls are usually fitted on the opposite side of the cranes servicing dedicated ballast tanks for these heavy cargo operations.
A final reason for side-mounted cargo gear arrangements is that these vessels usually carry 'project cargoes' such as long prefabricated segments of pipelines, wind turbine components, airplanes, motor yachts, etc. Removing the obstruction of a mast-house and crane structure from the center line of a vessel allows for the loading of these very long cargoes continuously on top of the ship's hatch covers.
Hope this answers a few questions!!!