Prop Shaft Systems
It is easy to connect an electric motor to a normal prop shaft. Install a generator to boost energy supplies..
Electric motors are now less expensive than a marine diesel of equivalent power. They can usually be connected to the existing prop shaft. However they do need significant battery power and the means to recharge those batteries. In most cases that means including a small generator as part of the overall package.
Prop shaft systems are better suited to sailing yachts where speed is not a factor. However most cruising sailors expect to be able to motor for 8 hours. With a 38Kw motor and at half throttle that means over 150Kw of electricity requiring battery capacity of at least 80Kw and a generator producing 20Kw - a sizeable beast!