How can a boat motor cause fatal injury, and how can owners reduce the risk?
I use a petrol outboard on our family motorboat, and the children often swim from the stern. Which motor hazards can be fatal, and what should I check or change before our next trip?
Answer
A boat motor can kill through propeller strikes, entanglement, carbon monoxide poisoning, fuel fires, electrical faults or loss of control leading to collision or drowning. Check the engine-stop system, steering, fuel system and exhaust first: reliable starting tells you nothing about dangerous faults in these systems.
Keep clear of the propeller
A rotating propeller can inflict deep wounds and fatal bleeding within seconds. Anyone falling overboard can also be struck by the boat or drawn into the propeller's path, particularly when the driver turns back towards them.
Electric propulsion demands the same precautions. A silent motor can remain enabled and produce thrust as soon as someone moves the throttle.
- Stop the motor before anyone swims near the stern, uses the boarding ladder or handles anything around the propeller.
- Remove the ignition key, magnetic emergency-stop chip or equivalent enabling device. Neutral alone does not prevent accidental engagement.
- Count everyone aboard and check the water around the boat before restarting.
- Wear the kill-switch lanyard, attached securely to your clothing or lifejacket, following the manufacturer's instructions.
Test the kill switch using the handbook's procedure, with cooling water supplied and everyone clear. Detaching the lanyard should stop the engine. If it does not, have the switch repaired before use.
Before clearing fishing line or removing a propeller, isolate starting and propulsion power as specified in the manual. Torqeedo Travel and Ultralight instructions also require you to stop the motor and remove the magnetic chip before tilting it out of the water.
Keep carbon monoxide out
Petrol and diesel engines produce carbon monoxide, an invisible, odourless gas that can kill without obvious warning. Exhaust can collect beneath bathing platforms, under cockpit covers and inside cabins. An engine running normally does not make these areas safe.
Check exhaust hoses, clamps, joints and outlets for damage, looseness, soot or leakage. If the installation has a waterlock silencer, inspect that too. Fit a carbon monoxide alarm approved for boat use in each relevant occupied space, following its positioning instructions. Check its test function and replacement date.
Never run an engine or generator in an enclosed boathouse. Keep swimmers away from exhaust outlets. Act immediately if anyone aboard develops a headache, dizziness, nausea or unusual drowsiness: stop the exhaust source if safe, move everyone into fresh air and seek urgent medical help.
Exhaust can also be sucked back aboard while underway, particularly behind a broad, abrupt stern or with cockpit covers erected. Volvo Penta's D6 guidance identifies speed, trim, loading, wind and openings as contributing factors. Opening forward hatches can increase this suction. If fumes enter, get people clear, stop the source when safe and investigate the airflow and exhaust installation before continuing.