While it’s extremely rare to find yourself completely out of power when out at sea, it’s always a good idea to be prepared, so you know how to react should it happen.

Usually, the cause of power failure is down to the charging system that fails, as opposed to the batteries. In fact, it’s very rare for yachts to only have one battery bank, and to not have a dedicated engine start battery.

If you have a long-distance cruising yacht, then you’ll usually have more than one means of charging a battery – for example, solar, wind vanes or hydrogenerators – that will help to back up your engine.

However, should you experience a power supply failure while out at sea, here is what you should do so you can get back to land safely.

Sort your navigation lights
If you’ve lost power production, then you have to reduce your consumption immediately, so make sure you prioritize what’s most important. Navigation lights should be at the top of your list, followed by a compass light. These are particularly important at night, as steering in the dark is incredibly difficult without it.

Review your batteries
Once you’ve sorted out your navigation lights, charge your engine start battery. If you are able to connect all of your batteries together, you may be able to split them, or use your solar panels or petrol generator to charge your engine start battery. Once it’s fully charged, keep it isolated and only use in case of emergencies.

If you can, do a quick audit all of your batteries on-board to see which are in the best condition. Reduce the number of batteries in your bank, to ensure you don’t run them all to a low level. You’ll need to continuously monitor them to avoid a total discharge.

Make small changes to your daily routine
If you know you are going to be out at sea for more than 24 hours with a power supply failure, then you need to make changes to your daily routine to ensure you don’t use up what little power you have left. For example, cook your evening meal while it’s still light outside, so you don’t need to switch your lights on while you’re preparing the food.

If you have solar-powered cockpit lights, then charge them up in the day so you can use them at night, without having to use your other power sources.

Prepare for the worst
While a total power failure is probably the last thing that comes to mind when preparing for your journey, by taking small steps to prepare for it before you set sail, you’ll be putting yourself in a good position if, for whatever reason, it should happen.

When you’re provisioning your boat, stock up on tinned food, so you’re not relying on food in the fridge alone. You should also bring an ice-box on-board, but only open it once or twice a day. That way, if you were to suffer a power failure, you should still have enough ice to put in your freezer to preserve the food.

Also, if you have a pressurized water system and don’t have a foot pump on your boat, buy a syphon pump too. They’re not expensive, but they’ll really help you out if you suffer from an electric pump failure, as you can pump the water manually.

Most common causes of engine breakdown
There are many reasons why your engine could fail, so there are lots of things you’ll need to check if that happens, such as:

  • Is the air filter blocked? You may need to clean or replace it.
  • Is the exhaust pipe blocked?
  • Is the oil filter blocked? You may need to replace it.
  • Are the drive belts worn?
  • Is the cooling water low?

You can find a full list of things to check here. We’ve also provided guidance of three of the most common causes of engine breakdown while out at sea, and how you can prevent this from happening.

Electrical system failure
Water in the bilge can shut down the engine, so it’s important to keep the bilge dry at all times. While it might take a bit of time and effort to sponge it out, it’s considerably better than having to replace the starter motor.

Running out of fuel
Boat fuel gauges can be inaccurate, so if you’re only a quarter full, rather than assuming you’ll be fine, fill up. Otherwise, you risk being left out at sea with an empty tank of fuel.

For motorboats, it can take 40 gallons to bleed the system before you can sail home, and it’s highly unlikely you’d actually carry such a large amount of spare fuel on-board.

Also, it may sound like common sense – but don’t accidentally fill your water tank with diesel or vice versa. It can be pretty easily done if you’re tired after a long day of sailing!

Battery isolator failure
A failure in the battery isolator can shut down your boat, causing a total power failure. Batteries often fail due to either cells dropping out, or a lack of fluid. Make sure you keep a power pack and a spare battery on-board, so should this happen while you’re out at sea, you can still get back safely.

While it’s very rare for you to endure an engine failure or power supply failure, it’s always ideal to know what to do should such a situation happen.

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