Immediate action on a boat
CPR and an AED on board
If someone is unresponsive and not breathing normally, start CPR. An AED on board is used as soon as it is in your hands.
If the person is unresponsive, call for help immediately, then assess breathing. You do not have to confirm abnormal breathing before that call. Ashore, call 999.
At sea, make that call to HM Coastguard on VHF DSC, channel 16, or MF DSC.
Source: Resuscitation Council UK, Adult basic life support guidelines (2025) MCA, MGN 623 (M+F) Amendment 1: Telemedical Advice Service (TMAS) for ships at sea
If they are unresponsive and not breathing normally, start chest compressions. Put the heel of your hand on the lower half of the breastbone, in the centre of the chest. Push down at least 5 cm but not more than 6 cm, at 100 to 120 compressions a minute. Let the chest come fully back up between compressions.
Source: European Resuscitation Council Guidelines 2025: Adult Basic Life Support
If you can give rescue breaths, give 30 compressions then 2 breaths. Each breath should be just enough to make the chest start to rise. If you have not been trained, or you cannot give breaths, do continuous chest compressions without stopping for breaths.
The Resuscitation Council UK 2025 community algorithm shows the same 30 compressions followed by 2 rescue breaths.
Source: European Resuscitation Council Guidelines 2025: Adult Basic Life Support Resuscitation Council UK, Adult basic life support in community settings (2025 algorithm)
Anyone can use an AED. Switch it on as soon as you have it, attach the pads to the bare chest as the pads show, and follow the voice prompts. Nobody should touch the person while the AED is analysing or delivering a shock.
Source: European Resuscitation Council Guidelines 2025: Adult Basic Life Support
If two attempts at a rescue breath do not make the chest rise, consider choking as the cause.
Source: European Resuscitation Council Guidelines 2025: Adult Basic Life Support
Continue CPR until professional help takes over, the person becomes responsive, or you are too exhausted to carry on.
Source: Resuscitation Council UK, First Aid Guidelines (2025)
Get certified
A certificate used for commercial work or offshore racing comes from hands-on training with a recognised provider, for example an RYA First Aid course or STCW Elementary First Aid. This online course does not award that certificate, and it does not name or recommend a training centre.
Check your understanding
You can answer without an account. Sign in if you want the answers kept.
1. How deep and how fast are adult chest compressions in the 2025 guidelines?
2. What is the compression to breath ratio if you are giving rescue breaths?
3. You are willing to help but you have never learned rescue breaths. What should you do?
4. An AED is in the grab bag. When do you use it?