HEALTH AT WORK

Industrial Health

Fishing Boat Crew Member Reporting Hearing Loss After Years Sleeping Near Diesel Engine Room

16 October 2026 · Health at Work · AI-assisted draft

Photo: Long Bà Mùi / Pexels

If you are a fishing boat crew member who has noticed that voices sound muffled, that you need the television louder than you used to, or that a persistent ringing follows you off the water and into your bunk, you are not imagining it. Years of sleeping in a cabin located directly above, beside, or below a running diesel engine room is one of the most underreported causes of occupational noise-induced hearing loss in any industry. The hazard is real, the damage accumulates silently over years, and by the time most crew members report symptoms, some of it is already permanent. This article explains exactly what is happening, what the early signs mean, and what both crew and vessel operators must do about it.

Why the Engine Room Below Your Bunk Is a Hearing Hazard

Commercial fishing vessels run their diesel engines continuously for days, weeks, or entire seasons. Unlike a factory worker who leaves the noise behind at the end of a shift, a crew member on a working vessel is exposed to engine noise not only while working on deck but while eating, resting, and sleeping. That continuous, round-the-clock exposure is what makes this hazard so damaging.

Diesel engines on mid-size and large fishing vessels typically generate noise levels between 85 and 105 decibels inside the engine room itself. Structural transmission means that this noise travels through the hull, bulkheads, deck plating, and into adjacent accommodation spaces. A crew cabin positioned one or two metres from the engine room bulkhead routinely measures 70 to 85 decibels even with the door closed. That may sound reassuringly lower, but the critical factor is duration. Sleeping eight hours in a space running at 75 to 80 decibels delivers a cumulative noise dose equivalent to working a full industrial shift at a much higher level. Do this every night for months at sea across a working career and the cochlear hair cells in the inner ear sustain progressive, irreversible damage.

Low-frequency diesel vibration adds a secondary effect. It does not directly damage hearing in the same way high-frequency noise does, but sustained whole-body vibration during sleep disrupts restorative processes, increases physiological stress, and may worsen the sensitivity of already-stressed hearing structures. Crew members in these berths rarely get genuinely restorative sleep, which compounds every other health effect on a demanding physical job.

Who Is Most at Risk on a Fishing Vessel

Any crew member whose sleeping or resting accommodation is adjacent to the engine room is at risk, but the level of risk varies by position on the vessel, role, and career length.

• Deckhands and junior crew are typically assigned the lowest and most forward berths, which on many vessel designs sit closest to the engine compartment. They receive the highest structural noise transmission and often have no choice over their bunk location.
• Engineers who sleep aboard between watch duties may spend extended time in or near the engine room, then rest in an adjacent cabin, compounding on-duty and off-duty exposure.
• Skippers and senior crew on smaller vessels often operate craft with no acoustically separated accommodation at all - the wheelhouse berth may be positioned directly over the engine.
• Crew on small inshore boats face a different pattern: shorter individual trips but years of daily exposure with little protective equipment and no formal noise assessment ever conducted.
• Workers in distant-water and deep-sea fisheries, where voyages last weeks and rotation back to shore is infrequent, accumulate the highest lifetime doses.

Career length matters enormously. A crew member who has worked a fishing vessel for ten years or more and slept aboard for most of that time has almost certainly received a cumulative noise exposure well above what most occupational health frameworks consider safe over a working lifetime.

Early Signs You Must Not Dismiss

The first signs of noise-induced hearing damage from engine room proximity are subtle and easy to rationalise away, which is why so many crew members present to occupational health services with moderate to severe loss already established.

• Difficulty following conversation in a noisy environment - a crowded dock, a busy galley, or a harbour-side pub - while one-to-one speech in a quiet room still seems fine.
• Asking people to repeat themselves more often, particularly when they are not facing you directly.
• Voices on the radio or phone sounding less clear than they once did.
• A temporary muffling or dullness of hearing after arriving in port, which clears after a day or two ashore. This is called a temporary threshold shift and it is a serious warning sign that permanent damage is accumulating.
• Tinnitus - a ringing, hissing, buzzing or tone that persists when there is no external sound. For many crew members this first appears during quiet moments ashore and is initially dismissed as tiredness.

Later-stage signs are harder to ignore but represent damage that is already done: permanent difficulty understanding speech even in quiet conditions, inability to hear high-pitched sounds such as alarms or birdsong, tinnitus that is constant rather than intermittent, and social withdrawal because conversation has become effortful and exhausting.

What Vessel Operators Are Required to Do

Under most occupational health and maritime safety regulations, employers who operate vessels with crew accommodation have a duty to assess and control noise exposure, and that duty extends to accommodation spaces as clearly as it does to working areas. The fact that crew are sleeping rather than working does not remove the employer's obligation - continuous exposure is continuous exposure, and regulators in most jurisdictions apply the same action thresholds to cumulative daily dose regardless of whether it occurs during a work task or a rest period aboard a vessel.

Vessel operators are expected to conduct a noise risk assessment that maps measured levels throughout the accommodation, not only in the engine room and on deck. Where measured levels in sleeping areas approach or exceed the lower action values recognised in most frameworks, operators must introduce controls. Relying solely on handing out earplugs and sending crew to bed does not discharge this duty - crew cannot be expected to sleep in hearing protection, and 'administrative controls' that require crew to manage their own exposure while asleep are not considered adequate.

Operators must also provide audiometric surveillance - regular hearing tests - for crew who are exposed above recognised thresholds. These tests should be conducted before first exposure, repeated at regular intervals during employment, and offered whenever a crew member reports symptoms. Records must be retained for the duration of employment and beyond.

Controls That Actually Work, in Order of Effectiveness

The hierarchy of controls applies aboard a vessel just as it does in any industrial setting, and the order matters because the lower down the hierarchy you go, the less reliably the control protects crew.

The most effective approach is to separate accommodation from the engine room structurally. On vessels being built or substantially refitted, this means locating crew berths as far from the engine room as the vessel layout allows, with acoustic insulation built into the bulkheads and decking between the engine space and the living quarters. Floating mounts that isolate engine vibration from hull transmission are standard practice in well-designed vessels and significantly reduce both noise and vibration transmission to accommodation spaces.

For existing vessels where relocation is not possible, secondary acoustic lining of the engine room bulkheads facing accommodation - dense mineral wool or mass-loaded vinyl - can reduce transmitted noise meaningfully, though rarely enough on its own to bring levels in berths down to safe limits if the starting level is high.

Quieter engine and generator sets, or fitting silencing to existing engines, address the source directly and are more effective than treating the receiving end. Where a vessel runs a separate harbour generator rather than the main engine while at berth, ensuring this is used whenever the vessel is stationary reduces the crew's exposure during the periods they are most likely to sleep for longer stretches.

Hearing protection is the least effective control for this specific hazard because it cannot realistically be worn during sleep. Earplugs should still be available and should be provided for time spent in or near the engine room during working hours, but they do not address the primary exposure route for sleeping crew.

What an Affected Crew Member Should Do Now

If you recognise any of the early signs described above, the first step is to report it clearly and in writing to your skipper or vessel operator. Do not wait until your next scheduled medical. Request an audiometric test - a formal hearing assessment conducted by an occupational health professional or audiologist, not a self-administered online check. This test will establish a baseline or, if previous tests exist, show whether your hearing has changed.

If you have already been experiencing temporary threshold shifts - that muffled sensation after time at sea - you need audiometric assessment urgently, because this pattern indicates that permanent loss may already be developing. An occupational health professional can assess your total exposure history, interpret your audiogram in context, and advise whether further specialist referral to an audiologist or ENT clinician is warranted.

Keep a personal record of your sea time, vessel types worked, and any symptoms as they develop. This record matters if you later need to demonstrate the occupational origin of your hearing loss.

What People Get Wrong About This Hazard

The most damaging misconception is that sleeping 'near' the engine room is meaningfully safer than working in it. It is not, once duration is accounted for. An eight-hour sleep at 78 decibels delivers more cumulative energy to the cochlea than a two-hour watch in the engine room at 95 decibels with correctly fitted hearing protection. The maths of noise dose is unforgiving and does not distinguish between work time and rest time.

A second common error is treating tinnitus as a nuisance rather than a symptom. Tinnitus following noise exposure is the auditory system signalling overload. Crew members who experience it regularly and do nothing are allowing damage to compound. There is no treatment that reverses cochlear hair cell loss once it has occurred - but there are measures that stop it progressing, and taking action while the loss is mild gives far better outcomes than waiting until it is severe.

Finally, vessel operators sometimes assume that because their crew do not complain, there is no problem. Crew on fishing vessels work in close communities with strong norms around toughness and self-reliance, and many will not report a hearing problem until it is impossible to conceal. Proactive audiometric surveillance, not waiting for complaints, is how this damage is caught early enough to matter.

Health at Work provides occupational health assessments and audiometric surveillance programmes for maritime and industrial employers. If you operate a vessel with residential crew, or if you are a crew member concerned about your hearing, contact Health at Work for a professional assessment tailored to your exposure history.