Water ballast is no longer the preserve of ocean racing yachts, it can now be found on performance cruisers and smaller racing boats. Pip Hare shares her top tips for using it


No two water ballast systems seem to be the same, but the principles for use and troubleshooting remain the same. Here are some guidelines for success.

Filling ballast

The ballast is filled via a scoop in the bottom of the boat, which is like a ‘reverse snorkel’. The snorkel is pushed down with the hole forward to fill the ballast, when the hole is facing aft the tanks can empty. To seal the system the scoop is retracted into the hull, leaving a flush finish.

A single scoop will be situated on the centreline, while twin scoops are placed outboard, so the leeward scoop must always be used for filling. When the scoop is pushed down, providing water is moving over the hull it will start to fire water into the boat. Filling can be achieved through continued forwards motion although this can take a lot of time so a pump is often used to accelerate the process.

Before pushing down the scoop, ensure all valves are in the correct position – this takes concentration if you’re not familiar with the system. Check:

  • Valve to leeward scoop is open.
  • Valves to leeward tanks are shut.
  • Valves to water pump is open.
  • Valves out of water pump are either directing towards windward tanks, or open on windward and closed on the leeward side.
  • Correct windward tanks are selected – you can fill multiple tanks at the same time.

Once the valves are in the correct position push the scoop down then turn on the ballast pump. Once water is overflowing from the breathers on deck, first close the tank valves, then shut off the pump and retract the scoop.

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If you’ve been running the ballast pump but the tanks are not filling then look for air in the system. Airlocks are a common problem with a pump and can be tricky to remove. Start by identifying where the lock is; transparent pipes are helpful. Then your objective is to flood that part of the pipe.

Every system will be different but things that can work include turning off the pump, rotating the scoop aft to empty for a few seconds, then face it forward and turn on the pump again. Or try changing the angle of heel to flatten the boat momentarily.

If all else fails, changing tack but leaving whatever ballast you have on the same side might shift the air. Tack, then tack back and try the whole process again.

Transferring ballast

Any manoeuvre involving transferring ballast is going to take time and it’s important to factor this into your planning and make sure you have enough ‘runway’ to complete your manoeuvre. For example, if you know it takes 140 seconds to drop the ballast and you’re sailing upwind at eight knots you’ll need one third of a mile to complete the tack from the moment you open the valves.

Use the time it takes for the ballast to transfer to get set up on deck for tacking and to move the stack to leeward (if allowed). Remember the trim of the boat will change while the ballast drops, so ease the mainsheet or traveller to control excess heel and feather the boat into gusts.

The process for transferring ballast is simple:

  • Check scoops are retracted and valves closed.
  • Open leeward tank valves, open transfer valves, open windward tank valves.
  • Once all water has transferred, close all valves.

The most common mistake is to close the valves and tack before all the water has run down. Sight glasses can help but they often don’t go to the bottom of the tank. Try putting your ear close to the windward transfer pipe, you should be able to hear water running through; if there’s no sound then the tank is empty. Water will rush out of the deck breathers on the leeward side but this may happen before the windward side is empty.

Always check the leeward side after a manoeuvre and empty out any water that’s left. Expect to top up the windward side over time.


Deck-mounted control rods can open or close the ballast transfer valves. Photo: Jean-Marie Liot

Dropping the ballast

There are no tricks to emptying the ballast, other than adding a little extra heel towards the end of the process. The routine is:

  • Push the leeward scoop down and turn it to face aft.
  • Double check leeward tank valves are closed.
  • Select the tank you wish to empty and open all valves between that tank and the scoop.
  • When finished close the valves and retract the scoop.

Management and maintenance tips

  • Put luminous tape on the scoops so you can easily see which way they’re facing in the dark.
  • Check inspection hatches and seals regularly. These hatches are a constant pain and expect them to leak. If going on a longer voyage, then take plenty of spare hatch seals and a couple of spare hatches.
  • Try very hard not to step on ballast pipes or valves.
  • Check both tank levels regularly. It’s not uncommon to lose water from the windward tank or for the leeward tank to start to fill over time.
  • Check all valves, particularly gate valves, are closing fully and also check the leeward deck breathers are not letting water into the tanks – which can happen if sailing with the rail constantly underwater or if the breathers are damaged.

First published in the May 2020 edition of Yachting World.