Book excerpt: Fernhurst Books' compact, handy guides to boat electrics and diesel engines bundled together in e-book form for the first time. The perfect quick reference guides to keep on your phone or tablet, easily accessible when you are on board. They contain all the essential information for when you need it most about keeping your boat electrics and marine diesel engine running. The Electrics Companion covers formulae, tools, anodes, protection, multimeters, soldering, AC power, testing, wiring, batteries, connections and power consumption. The Diesel Companion details the parts of the engine and has checklists for monthly, weekly and daily checks. It outlines what to do if the engine won't start, or stop, if it overheats or there are problems with the fuel system. It tells you about servicing, the electrics and winterisation. This will be a valued companion when the electrics or engine doesn't behave.