It’s the middle of July on the last day of a wonderful week long cruise along the West Coast of Scotland in your 1991 flybridge cruiser.

The skies are blue and you’ve been enjoying the sun up on the flybridge as you cruised to your designated anchorage for a bite to eat before completing the final leg back home. The weather is set fair for the next 24 hours and you and your partner are due back to work the next day.

The time is 2pm and you are about to up anchor after lunch, and start the journey back to your berth 90 miles away. You settle down at the inside helm seat and go through your usual starting routine. The port engine fires up as normal but when you try to start the starboard engine nothing happens. All the normal ignition lights are on but there’s no sound of a starter motor turning.

Your engines are standard non-electronic diesels with cable control of the throttle and gears. Each key works very much like the one in your car except that there’s a spring-loaded position to the left of ‘Off’, which you use to shut down the engine. You have a push the button on the dash that says ‘Battery Parallel’, which you have never previously had to use. Somewhere in the depth of the lazarette is a pair of car ‘jump leads’ that you inherited with the boat.

On two engines you can cruise at 28 knots. On one engine you can make only ten knots. The final stages of the route require some tricky pilotage and you do not fancy having to do it in the dark. How would you go about tracing and curing the fault? And what if you couldn’t?

Email your answers to paul_ashton@ipcmedia.com