The following safety information has been kindly supplied by RNLI:
In 2010, lifeboats were called out 1,740 times to boats with machinery failure, and 165 times to boats that had run out of fuel.
If your craft has an engine, we strongly recommend that you know the basics of starting, running and maintaining it. Appropriate spares should be carried onboard and fuel use should be calculated on approximately one third for the outward trip, one third for the return and one third as spare. Do not rely on fuel gauges, as these have been know to be faulty.
Where possible, an alternative means of propulsion should be carried. Engine failure alone is not a distress situation; it does not warrant a Mayday call or the use of flares, unless lack of power has put the boat and crew in grave and imminent danger.
The RYA runs a 1-day diesel maintenance course that aims to give boat owners the basics. The ISA also runs a basic marine engine course.