CruiseLink
Does Bluetooth messaging actually work on a cruise ship?
Yes, with one condition that decides everything: enough of the people you care about have to be carrying it. The radio is not really the problem. Nearly every story of a mesh app failing at sea is a story about there being nobody nearby to mesh with.
This page is the measurements rather than the theory, including the ones that went badly.
The failure first
Before CruiseLink existed, we tried an existing Bluetooth mesh app on a real sailing. It failed.
The reason matters, because it is the reason most of them fail: three people on the ship had it installed, and they were not near each other. A mesh is not a magic radio. It is a network made of other people's phones, and with three phones on a 5,000-passenger ship there is no network to join.
That tells you nothing about steel or batteries. It tells you the thing that actually decides whether this kind of app works, which is whether your group has it. Not strangers. Not the ship. Your group, installed before you sail.
What happened once a real group had it
A family of six spent an afternoon and evening together with no shared wifi — a meal, then an arcade, moving around in pairs and swapping about. One Android phone's own log for those four hours:
| Completed exchanges per hour | Same person re-found every | |
|---|---|---|
| Sitting at dinner, 16:00–18:00 | 90 | 4.2 and 4.4 minutes |
| Walking round an arcade, 18:00–20:00 | 60 | 6.0 and 7.4 minutes |
317 completed exchanges across those four hours, every single one over Bluetooth and none over wifi. Two people were re-reached 35 and 33 times.
The useful detail is the second row. Moving about cost roughly a third of the throughput and about two minutes of gap — it did not stop it. People worry that walking around breaks this kind of app. Walking around is what makes it work, because a phone that moves is a phone that carries messages.
Where steel actually bites
A ship is a stack of steel floors. Radio travels along a deck far better than through one, which is also why walkie talkies disappoint people onboard.
What that means in practice is not "it does not work" but "it is not instant". A message from a top-deck bar to a cabin low down with nobody in between waits until somebody moves between them. On a ship of several thousand people somebody usually does, quickly. Sometimes they do not.
The ship's own network, which nobody mentions
There is a second route, and it is the one most people have never heard of.
On P&O's Arvia, devices on the guest network reached each other across different decks and different subnets — including devices that had not bought an internet package. The captive portal was charging for the internet, not for the ship's own network.
Stated honestly, because it matters: that was one ship, one voyage, one line. It does not prove Royal Caribbean, Carnival, MSC or Princess behave the same way, and a single configuration change would end it. It is a bonus when it is there rather than something to rely on.
So what decides it
- Did your group install it before sailing? This is the whole answer. Nothing installs at sea.
- Are you roughly in the same part of the ship during the day? Families usually are, far more than they imagine.
- Is Bluetooth on and the app allowed to run in the background? It cannot carry anything with the radio off.
Get those three right and it works about as well as the numbers above. Get the first one wrong and it does nothing at all, which is precisely what happened the first time we tried it.
What we will not claim
- Not instant across a whole ship. Anyone claiming otherwise has not measured it.
- Not a tracker. It tells you when somebody was last reached, not where they are.
- Not a way to reach home. Nothing leaves the ship.
- Not useful to one person. It is a group tool and a group of one has nothing to talk to.
Get CruiseLink
Free, no account, nothing to set up beyond your group. On iPhone and Android, and the two work together.
