There's no great need to dismantle a servo
to get motive power - nowadays you can buy model motor
s that are not much thicker than a typical boat propshaft
, and speed controller
s the size of a thumbnail. Usually for about a pound. These small drones have really helped in this regard. This one, for instance, is 0.6cm diameter by 1.5cm long - https://www.ebay.co.uk/itm/Original-JJRC-H20-RC-Drone-H20-08...
Your biggest problem will usually be rudder
control - there will be little room for a servo
and tiller right at the stern
of small boats. For an EeZeBilt I recommend a closed loop system
which lets you relocate the servo
anywhere convenient - see http://eezebilt
.tk/radio.html The EeZeBilt Terrier below is 10.75 inches long...