How Cruise Ship Stabilisers Actually Work (And Why They Are Important To Me!)

Many people are surprised to know that I sometimes get seasick.

Not just seasick, actually, I get motion sick in general. I can be unwell on long car journeys, on coaches or buses, and even sometimes on VR games.

I never go far without a packet of travel sickness pills in my bag. If I am going on a long car journey, on a cruise ship bus excursion, or if the Captain mentions bad weather, I take some.

Although I never go on a cruise thinking I am going to be seasick, I know if the seas get rough, it is always a possibility.

I wish I was one of those lucky people that isn’t affected by the movement of the ocean. I have never seen my mum or brother feel ill at sea – even when my dad and I feel terrible and are confined to the cabin!

New ships have the most modern equipment onboard and are built with stabilisers to help keep them stable in rough seas.

Older ships can be retrofitted with stabilisers, but somehow these don’t seem quite so effective.

One of the things I think about before I book a cruise is the ship itself. I know that if I am on an older, smaller ship, the risk of seasickness is greater for me.

What Are Cruise Ship Stabilisers?

Stabilisers reduce the ship’s side-to-side movement in rough seas.

On most ships, a gentle rolling from side to side isn’t much of an issue, but on a cruise ship, where guests may be eating, drinking, performers are onstage, and guests are constantly moving around the ship, it needs to be more stable.

No one wants their glass of champagne sliding off the table and into their lap!

How Do They Work?

To feel stable, the ship needs to remain upright in the water, and the waves need to run underneath her rather than rolling with the seas.

The stabilisers fitted need to counter the force generated by the wave.

That force is not constant, though. As the wave hits the side of the ship, the force is at its maximum, and the ship wants to tip over.

As the wave moves under the centre line of the ship, the force becomes far less (nearer zero). Then, as it reaches the other side of the ship, the tipping force becomes a maximum again, but in the other direction.

The stabiliser needs to be able to change the amount of force the wave generates. The amount of force the stabiliser generates depends on the exact position of the wave under the ship.

The amount of force produced by the stabiliser, therefore, has to be constantly changing.

Fin Stabilisers Are Mostly Used on Cruise Ships

There are various types of stabilisers used on ships, but most modern cruise ships use fin stabilisers.

These large, hydraulically operated wing-like structures extend from both sides of the ship below the waterline.

These fins can tilt to counteract the ship’s rolling motion. They are gyroscopically controlled, moved and adjusted to push against the roll, stabilising the ship.

Have a look at fin stabilisers and how they move in this fascinating video by SKF (who retrofit them) below:

Other Common Types of Stabilisers:

• Gyroscopic Stabilisers:
  • These use spinning gyroscopes to stabilise the ship, they are more common on smaller vessels.
    • They work by using a large spinning wheel (flywheel) that counteracts the vessel’s rolling motion by applying force in the opposite direction.
    • This helps to stabilise the ship making it smoother and more comfortable to sail in on rough seas.
• Bilge Keels:
  • These are fixed fins that reduce rolling through resistance.
    • They are often found on older or smaller ships.
    • They dampen any roll and are cheap to install, but because they aren’t adjustable, they are not effective enough for cruise ships.

I took a very rough transatlantic crossing on the last Ocean Liner at sea, Queen Mary 2. She was designed specifically to make these crossings in all sea conditions.

She has four Denny Brown stabilisers, which significantly reduce the ship’s roll. These stabilisers, each weighing 70 tonnes and extending 6.2 metres from the hull, can reduce roll by up to 90%.

This makes her one of the most stable passenger ships at sea. The stabilisers are positioned two on each side of the ship.

Have a look at the rough seas I encountered and how the Queen Mary 2 dealt with them in the short video below:

When Are They Used?

Stabilisers are only effective when the ship is sailing.

They need a water flow across them to work. If the ship’s speed isn’t high enough, they don’t create enough force to counteract the ship’s movements.

Luckily, cruise ships sail at speeds well above the speed needed to make the stabilisers effective.

This does explain why slow cargo ships don’t use fin stabilisers, though.

Do They Prevent Seasickness?

While stabilisers significantly reduce rolling, they don’t eliminate all motion.

If you’re prone to seasickness, taking precautions like choosing a midship cabin on a lower deck and bringing seasickness remedies is still a good idea.

I chose a central, low-down cabin for my transatlantic crossing. My parents had a balcony cabin, high up and at the front of the ship. The movement and noise of the ship crashing through the waves was far, far worse there.

Have a look at that very memorable trip here:

Can Older Ships Be Retrofitted With Stabilisers?

Several cruise ships have been retrofitted with new or upgraded stabilisers to improve stability and reduce roll, especially in rough seas. 

Cruise lines and ferry companies that have retrofitted or upgraded stabilisers on their ships include:

• Fred. Olsen Cruise Lines
• Marella Cruises
• Corsica Linea
• DFDS
• Stena Line:

Have a look at the cruise I took on Fred. Olsen’s Bolette, “In search of the Northern Lights”.

Choosing an older ship to cross the North Sea in February wasn’t such a good idea, with hindsight!

Although Bolette has been retrofitted with stabilisers, the movement of the ship made me very ill.

Find out more about that here:

Downsides Of Using Stabilisers For The Cruiseline

Stabilisers on cruise ships do have an impact on the amount of fuel used by the ship.

Fuel consumption is increased because they add drag to the ship’s hull.

Captains have to balance passenger comfort with fuel economy in rough seas.

Stabilisers are used when needed, primarily in rough seas, to minimise rolling.

Stabilisers are typically retracted in calm waters or when docking to reduce drag and improve the ship’s manoeuvrability. They won’t have the stabilisers out unless it is absolutely necessary.

Before You Go

Find out the best position onboard to book your cabin, if you are concerned about seasickness here:

What is The Best Cabin Location on a Cruise For Avoiding Seasickness? (I’ve Tried Them All!)

My parents got an “upgrade” to a balcony cabin on Queen Mary 2. With hindsight, they would have been better sticking with their obstructed view cabin down on deck 8. Find out more about that here:

Why I Wouldn’t Recommend This Balcony Cabin on Queen Mary 2 (Full Cabin Review)