A new junior stew decants an unlabelled acid rust remover into an empty bleach bottle because it was the only container to hand. Two days later, someone else uses that bottle in a small, poorly ventilated laundry, believing it is bleach, and mixes it with a hypochlorite product. That is a chlorine gas incident in a confined space, in the middle of an ocean, with no shoreside emergency service.
COSHH and the SDS
COSHH (Control of Substances Hazardous to Health) is the UK framework, and its logic is the international standard for handling chemicals aboard: assess, control, inform, train, monitor.
Every chemical carried must have a current Safety Data Sheet (SDS) — the 16-section document supplied by the manufacturer. The sections a steward(ess) actually uses:
| Section | Content | Why you need it |
|---|---|---|
| 2 | Hazard identification | GHS pictograms, signal word, hazard statements |
| 4 | First aid measures | What to do in the first sixty seconds after a splash |
| 7 | Handling and storage | Segregation, temperature, ventilation |
| 8 | Exposure controls / PPE | Gloves, eye protection, respiratory |
| 10 | Stability and reactivity | What it must never be mixed with |
| 13 | Disposal | MARPOL-relevant; what may not go over the side |
Keep the SDS file in the laundry, current, complete and accessible — not on someone laptop. Assessors and Port State Control both ask for it.
Storage rules
- Original, labelled containers only. Never decant into a food, drink or other product bottle.
- Store low down and secured — in a seaway, a chemical shelf at head height is a chemical shower.
- Segregate incompatibles: acids away from bleaches (chlorine gas); oxidisers away from flammables and organics.
- Cool, dark, ventilated. Peroxide and percarbonate products degrade with heat.
- Keep quantities minimal. A yacht is a confined space; a season worth of chemical is a hazard, not a saving.
- Spill kit, eyewash and correct PPE (nitrile gloves, splash goggles) present and known.
Never mix
| Combination | Result |
|---|---|
| Chlorine bleach + acid (rust remover, limescale) | Chlorine gas |
| Chlorine bleach + ammonia (some glass cleaners) | Chloramine gas |
| Chlorine bleach + hydrogen peroxide | Violent reaction, oxygen release |
| Different brands of concentrate | Unpredictable; never assume compatibility |
Onboard Notes
- Deliver a toolbox talk on the laundry chemicals to every new stew on their first day, before they touch a bottle, and record it. As a senior, that training record is your protection as much as theirs.
- Chemical waste and rinse water are governed by MARPOL and the yacht garbage management plan. Nothing goes over the side because it is convenient.
- Dilution is not a control measure on its own. Dose with a measure or an automatic dosing system, not by eye.
- If someone is exposed: SDS Section 4, then the medical officer, then log it as an incident. Do not wait to see if it settles.