The following key advantages of shaft drive propulsion for a global cruising yacht are an important decision factor for anyone considering such a voyage.
Shaft drive systems are much lower maintenance than sail-drives. There is no complicated gearbox that must be serviced, or aluminum housing in the water that is prone to galvanic corrosion.
You don't need to haul the boat for servicing shaft drives. This is especially important for a global cruising catamaran, as haul out facilities can be difficult to find, and expensive.
Best Handling Under Power
By using a shaft drive, the propellers and shaft exits are placed for best handling under power (in front of the rudders) and have minimal drag (at junction where the keel meets the hull at a point where disruption of flow would be minimized). Additionally, the props located deep in the water are not subject to aeration in a heavy seaway and there are no restrictions to the choice of propeller style.
Moving the engines close to mid-ship, provides a favorable wave reaction motion, which results in a more comfortable sail.