Another cheap project I did last summer was my outboard engine hour counter.
I treated "Rockhopper" last summer to a new outboard. Like most of the smaller engines it does not come with an hour meter. So how would I know when to do the next service
I found a simple solution for just over £10 on fleebay: An hour meter that works via induction from the spark plug. No batteries, no complicated connections.
All I had to do was to wrap the induction wire around the wire that goes to the sparkplug inside the engine.
Then fixed the wire with twist ties and self amalgamating tape.
Finally stuck the meter with outdoor double sided tape inside the outboard.