On small private aircraft the engine is placed at the front of the fuselage, or on the wings E.g. Stationair, Otter
On combat aircraft the engine/s is placed at the end of the fuselage E.g. Raptor, Typhoon
On larger aircraft constructed to carry cargo/passengers the engines are placed on the wings E.g. DC3, A380
The positioning probably has to do with the amount of load to be lifted into the air, and manouverability desired... which seems sensible.
Yet most water-going craft (boats, power-boats, merchantmen, naval craft) have their propellers/push-pull placed at the back of the fuselage.
What is the advantage in placing the driving component for boats in this position in addition to protecting them against damage? Can the propellers on a boat, with adequate protection say- a tubular enclosure, placed alongside the fuselage not drive the watercraft with equal efficiency and power?