It seems like every week there’s another cruise ship breaking free from the dock – and passengers are left wondering how on earth these floating hotels manage to slip away like runaway balloons.
Well, I’ve spoken to a real port pilot to find out exactly what’s going on behind the scenes. Let’s break it down.
It’s Windier Than You Think
When cruise ships dock, they’re secured with a very specific arrangement of ropes (called mooring lines). But even with multiple lines holding them in place, a sudden gust of wind can push with tons of force. Literally.
“The pressure on the side of the ship rises exponentially with wind speed,” the pilot explained.
To calculate this, crew members use a formula that estimates the force based on wind speed and the size of the ship’s exposed side. While the formula itself is precise, the windage area (the total square metres exposed to the wind) often has to be estimated, especially when exact dimensions like air draft aren’t available.
Here’s a rough idea of how much force the wind can apply on a huge cruise ship like Icon of the Seas (365 metres long):
- Force 3 (Gentle Breeze – 8 knots): 21 tons
- Force 6 (Strong Breeze – 25 knots): 128 tons
- Force 8 (Gale – 37 knots): 449 tons
That’s right — a bit of extra wind can turn into hundreds of tons of sideways force. The bigger the ship, the bigger the target for the wind.
The size of the ship makes a bit difference too. Take a look at this table which shows how much more pressure is placed on bigger cruise ships compared to smaller ones…
| Ship | Gentle Breeze (Force 3 – 8 knots) | Strong Breeze (Force 6 – 25 knots) | Gale (Force 8 – 37 knots) |
|---|---|---|---|
| Icon of the Seas (365m long) | 21 tons | 128 tons | 449 tons |
| Serenade of the Seas (294m long) | 13 tons | 128 tons | 284 tons |
| Silver Moon (212m long) | 8 tons | 79 tons | 174 tons |
As ships have grown bigger, the forces involved have grown too, making even a short burst of wind enough to overwhelm carefully planned mooring setups.
Recent Scary Incidents
Let’s take a closer look at some of the incidents we’ve seen recently…
Celebrity Edge — Juneau, Alaska (16 June 2025)
Severe weather hit as passengers enjoyed their port day in Alaska. Gusts of up to 60 mph snapped the mooring lines, and Celebrity Edge drifted into open water. The crew quickly regained control, but not before giving everyone a good scare.
MSC Seascape — Ocean Cay, Bahamas (31 May 2025)
MSC Seascape faced its own drama while docked at Ocean Cay, MSC Cruises’ private island in the Bahamas.
A sudden squall snapped the lines, dropped the gangway into the water, and injured a guest who was disembarking. Thankfully, they were treated onboard and rejoined the cruise shortly after.
Norwegian Epic — Catania, Italy (30 May 2025)
In Sicily, strong winds ripped Norwegian Epic’s mooring lines free, sending parts of the dock flying. Two passengers fell into the water when the gangway collapsed, but were rescued quickly with only minor injuries.
Westerdam — Ketchikan, Alaska (30 May 2025)
Westerdam broke loose in Ketchikan after sudden 60-knot winds caused the ship to shift dramatically. Passengers caught the moment on camera as the gangway dangled before plunging into the sea.
How Do Ships Normally Stay Tied Up?
Here’s a super simple version of how cruise ships stay put:
- Headlines & stern lines: these pull the ship forward and backward to keep it snug against the dock
- Breast lines: these hold the ship close to the dock sideways
- Spring lines: these prevent the ship from surging up and down along the dock.
“A typical big cruise ship might use something like six or seven lines forward, six or seven lines at the stern, and two or three spring lines at each end,” the pilot told me. “We always err on the side of caution, especially with larger vessels.”
So with all these lines in place, how can things still go wrong?
It’s All About Balance
For mooring lines to do their job, the tension needs to be perfectly balanced. If one line takes too much strain, it can snap. And when one line goes, the extra load shifts to the others — which can also fail in quick succession.
“Lines are most likely to break if they are not tensioned evenly – and sometimes it’s obvious when that happens,” the pilot said.
It’s not just about the ropes either. The metal posts on the dock where the lines are secured (called bollards) also have their limits.
“I’ve seen bollards rated up to 200 tons, but many are much lower,” the pilot added. “That’s why we always try to spread the lines across multiple bollards.”
The Equipment Matters Too
Most cruise ships use drum winches, which require the crew to manually adjust line tension. Some cargo ships use self-tensioning winches that automatically adjust as tides rise or winds shift.
“Self-tensioning winches are very effective – but even they can be overwhelmed if a sudden squall hits and the wind pressure exceeds the setting,” the pilot explained. “That’s when you see them paying out – and that’s when you lose your gangways.”
In other words, even the best equipment can’t always keep up when Mother Nature throws a tantrum.
“Tending the moorings whilst a ship is alongside is vital,” the pilot stressed.
The crew monitor the tension continuously, making adjustments as conditions change – but some storms escalate so fast that there’s little time to react.
When It’s Just Too Dangerous
When bad weather is forecast, captains and port pilots have tough decisions to make. Sometimes that means calling in tugboats to push the ship against the dock. Other times, they may choose not to dock at all.
“In extreme cases, if offshore winds are forecast, we’ll employ tugs to push up,” the pilot said. “But sailing early or aborting the call completely is often the safest option.”
The Bottom Line
Cruise ships breaking free from the dock might seem like freak accidents, but there’s a lot of science behind why it happens. When strong winds hit these giant floating hotels, even dozens of heavy-duty ropes and powerful winches can struggle to keep them in place.
So next time you’re relaxing on board in port, spare a thought for the crew – and the port pilots – who are constantly watching the skies, calculating forces, and making sure your cruise ship stays exactly where it’s supposed to.
Related Posts:
- How Ship’s Pilots Guide Cruise Ships In And Out Of Port
- How Much Money Cruise Captains Make
- The World’s Most Dangerous Cruise Ports: Revealed
Jenni Fielding is the founder of Cruise Mummy. She has worked in the cruise industry since 2015 and has taken over 30 cruises. Now, she helps over 1 million people per month to plan their perfect cruise holidays.
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