On board, the confined spaces are called enclosed spaces, and their geometry is what makes them different from shore-side vessels: vertically layered, served by a single hatch, poorly ventilated in the dead corners, with residue in the bilge generating gas continuously. The workable approach is not to place a detector at every hatch but to link detection, ventilation, attendance and entry control into one chain.
Which spaces on board count as enclosed spaces
Cargo holds, ballast tanks, fuel tanks, sewage tanks, cofferdams, pump rooms, machinery space bilges, double bottoms and pipe ducts. Nobody enters them in normal operation, yet cleaning, repair and hot work all require entry — which is also why they are a standing focus of maritime inspections.
Three things the equipment has to watch
Gas. Test oxygen, toxics and flammables before entry. The common yardsticks: oxygen not below 19.5%, carbon dioxide not above 2%, flammable gas not above 1% of the lower explosive limit, toxics against the applicable exposure limits — then continuous monitoring while the job is under way.
People. Who went in, and how many are still inside. This is the link that breaks most often when contract crews board for repairs: neither side is familiar with the other’s routines or permit process.
Ventilation and attendance. In machinery space bilges and cofferdams, concentrations rebound once ventilation stops, so the attendant stays at the hatch for the full duration of the job.
The unit at the hatch does more than the unit inside the tank
Data displayed only inside the tank is data nobody can act on — and an attendant leaning into the opening to look is itself a violation. The fix is to bring the data to the entrance. The LSM3000 confined space monitoring station splits into internal and external units: the external unit mounts at the hatch and shows concentration curves, the headcount inside and live video, while a gas detection ball and smart wristbands collect the readings inside.
What the equipment covers — and what it cannot replace
Equipment covers the seeing and the watching that people cannot sustain. Permit approval, forced ventilation, toolbox briefings and emergency drills remain mandatory, and GB 46768-2025, the technical code for confined space operations in force from 1 May 2026, sets requirements for testing, attendance and record-keeping. One rule admits no exception: if a person has collapsed inside, never enter to rescue without a self-contained breathing apparatus.
Can shipboard equipment be the same as shore-side?
The principles carry over; the difficulty is geometry. Hatches are small, spaces are deep and the layers are many, so the equipment has to pass through narrow openings and reach the far end of deep compartments.
Configure for the chain, not the hatch count. Tell us the vessel type, the compartments and the work pattern, and we will propose the sensor, entry control and attendance layout that fits the way your crews actually board and work.