It will almost always be possible to buy a petrol outboard for less. So why did I do it? Well, my motivations were as follows: 1. To keep myself occupied at home, alone, over the long nights of a Scottish winter (over previous winters I’ve constructed a navigation system, an autopilot and solar water heaters). 2. Because I wanted a system that was more powerful than the cheap trolling motors, but much cheaper than equivalent commercial units (an equivalent ePropulsion Spirit currently retails at around £1,500) 3. Because I have longer-term aims of making the system fully remote controlled (essentially a drone, perhaps for wildlife photography), and for that I needed complete mastery of the control system, which is achievable if I build it myself. To embark on a project like this requires a basic knowledge of electronics and mechanics, but should be within reach of most practical people with a willingness to learn. The voltages are low enough that they should not present an electrocution risk but take all appropriate precautions when working with electricity and moving mechanical parts. My project utilised computer control and a lot of new-to-me equipment such as touch screens, ...