Sleep Apnea at Sea and What Maritime Medical Fitness Rules Mean for European Seafarers

What a Sleep Apnea Diagnosis Does to Your Seafarer Medical Certificate

A sleep apnea seafarers medical fitness certificate decision is a pause, not an ending. The ILO/IMO Guidelines on the medical examinations of seafarers file the condition under ICD-10 G47 and make you temporarily unfit until treatment has started and worked for three months. You then sail again on a time-limited certificate with six-monthly compliance assessments. Permanent unfitness is reserved for treatment that fails, or for a seafarer who does not comply.

Aviation is a separate chain, so EASA certification for pilots with sleep apnea reads nothing like a seafarer medical. The pages that rank are American, built around waivers Europe does not have.

Those come from on-board polysomnography of merchant navy crew. Of those tested, 73.7% had at least mild OSA (an apnoea-hypopnoea index, or AHI, of 5 or more), 47.4% an AHI of 15 or more, and 15.8% severe disease, with mean AHI 18.2 per hour and snoring at 86.7% (Kerkamm et al., International Journal of Environmental Research and Public Health, 2023). The sample was small: 19 male seafarers across three vessels.

Two Things Almost Every Seafarer Medical Guide Gets Wrong

Flaw one: the advice is written for the wrong regulator

The page that owns this query is entirely United States Coast Guard. It answers sleep apnea in one FAQ line and stops. No AHI threshold, no adherence metric, no MLC 2006 Standard A1.2, no STCW Regulation I/9, and no mention of the fitness categories a European examiner uses.

Flaw two: the pages selling you the medical never discuss the condition

ENG1 booking pages cover price, validity and where to attend. Across that whole cluster "sleep apnoea" appears once, buried in a weight question, with no numbers. They confirm an appeal exists without saying what triggers the failure.

The deeper problem: nobody screens you for it

Neither the ILO/IMO guidelines nor the MCA Approved Doctor's Manual contains any OSA screening instrument. No Epworth Sleepiness Scale, or ESS. No STOP-BANG questionnaire. No neck circumference threshold. Even the handbook seafarer medical examiners use has a chapter titled "Loss of consciousness, altered awareness, epilepsy and sleep disorders" with no obstructive sleep apnoea guidance in it. Detection depends on you volunteering symptoms, or on the doctor routing there through obesity or blood pressure.

The Sleep Apnea Seafarers Medical Fitness Certificate Rules in Plain English

Three documents govern this. The ILO Maritime Labour Convention 2006 (Standard A1.2) and the IMO STCW Convention (Regulation I/9 and Section A-I/9) set who needs a certificate and how long it lasts: two years maximum, one year under 18, colour vision six years. The ILO/IMO Guidelines (ILO/IMO/JMS/2011/12, ILO Geneva, 2011) set the medical criteria. Your flag state administration writes its own standard on top.

The United Kingdom codes this as MSN 1886 item 6.8, using four fitness categories. Category 1 is fit for sea service with no restrictions. Category 2 is fit with restrictions, where a no-watchkeeping restriction or a near-coastal waters restriction gets recorded. Category 3 is temporarily unfit, Category 4 permanently unfit.

Sleep apnea starts at Category 3. It becomes a time-limited Category 1 once treatment has worked for three months with CPAP compliance confirmed, then six-monthly assessments read off the machine's own recording. Category 4 applies only where treatment is ineffective or the seafarer is non-compliant. The ILO/IMO certificate form carries a "Fit for lookout duties? Yes/No" field, so a sleepiness-related restriction is recorded on the face of the certificate itself.

Among 43,758 Norwegian seafarers examined in 2018 to 2019, those given a time-limited certificate had a 2.45-fold higher risk of acute somatic hospital admission at three to 24 months than those given a full one (Gulati et al., BMJ Open, 2025).

One question the guidelines never answer: who pays for the sleep study. Polysomnography, respiratory polygraphy or a home sleep apnoea test runs through your national health system or an employer's scheme, and no maritime instrument assigns the cost. Settle it before booking.

The Three Shipboard Conditions Attached to a CPAP User's Certificate

These conditions decide most sleep apnea seafarers medical fitness certificate outcomes in practice, and no ranking page mentions them. The MCA Approved Doctor's Manual (July 2020, ADG 7, Chapter 4, item 4a) attaches all three to a CPAP user's fitness.

The Same ILO Baseline Produces Very Different National Burdens

Every sleep apnea seafarers medical fitness certificate decision in Europe starts from the same ICD-10 G47 row, then diverges. The flag on the stern changes what you must prove.

Ireland handles the whole condition in one line in Marine Notice 38 of 2014: seafarers with sleep disorders "should have careful assessment: significant symptoms with unpredictable drowsiness will be deemed unacceptable until adequately treated and controlled." Cases needing approval go to the Marine Survey Office, Irish Maritime Administration, Dublin.

The obesity gateway is how most seafarers arrive here

Most crew reach an OSA referral sideways, through weight or blood pressure. Ireland states that a body mass index above 35 is unacceptable for seafaring duties, and resolves BMI 30 to 35 with a Chester Step Test, average or better meaning fit. UK MSN 1886 item 3.5 puts BMI over 35 at Category 3 worldwide until reduced, with a target weight agreed. The ILO/IMO guidelines caution that BMI "should not form the sole basis for decisions on capability".

France runs seafarer fitness through a state health service, with data held in the national Aesculapius database. Permanent unfitness is rare: 2,392 French seafarers were declared permanently unfit between 2005 and 2016, below 1% of those examined (Loddé et al., Journal of Occupational Medicine and Toxicology, 2021). Fishing accounted for 67%, and small fishing vessels are where a private berth, stable power and spares are hardest to arrange.

Sleep Apnea Seafarers Medical Fitness Certificate Compliance and Running CPAP in a Cabin

Nobody tells you what number the download has to show. No maritime instrument names a threshold. The clinical literature does use one.

In an individual-participant meta-analysis of 4,186 patients with OSA and cardiovascular disease, mean CPAP adherence across the trials was only 3.1 hours per day. Intention-to-treat showed no benefit, while good adherence of four hours or more per day was associated with fewer recurrent major adverse cardiac and cerebrovascular events, hazard ratio 0.69 (95% CI 0.52 to 0.92) (Sánchez-de-la-Torre et al., JAMA, 2023). Four hours a night is the cut-off that evidence anchors; no maritime rule offers a competing one.

Why the margin is thinner at sea

You start from a sleep debt before the mask goes on. In the same shipboard study mean total sleep time was 323.2 minutes, about 5.4 hours, and 283.3 minutes among watchkeepers; the arousal index was 29.4 per hour against 14.5 in the normal population. Increased daytime sleepiness on the Epworth Sleepiness Scale (ESS above 5) affected 61.1%, and 16.7% had excessive daytime sleepiness (Kerkamm et al., 2023).

Rostering runs on hours of rest under STCW and hours of work under MLC 2006. A field study of 63 UK ferry workers found on-duty sleepiness at Karolinska Sleepiness Scale, or KSS, 7 or above in 27% of shifts. Its authors recommended avoiding split shifts and concluded that current regulations are insufficient to manage fatigue effectively (Sjörs Dahlman et al., Chronobiology International, 2026).

Five cabin problems to solve before you sail

1. Power. Check shipboard voltage and frequency, whether a 24 V DC outlet exists, and whether cabin sockets switch off at night.
2. Water. A heated humidifier needs distilled water and almost no vessel stocks it. Carry your own or run dry.
3. Condensation. A hot cabin plus a humidified circuit means rainout in the tube. Insulate the hose or lower the setting.
4. Noise. Mask leak, not the blower, wakes a bunkmate. Refit the cushion and test the seal ashore.
5. Continuity. Auto-CPAP, or APAP, travels well but still fails. Spares are a certificate condition, not a preference.

Those constraints make travelling with sleep apnea away from a fixed home setup hard, multiplied by a four-month contract.

Your First Ninety Days, and What Happens If You Fail

Treat the three months as a project. The clock runs from treatment working, not from diagnosis.

1. Declare it at the medical. No screening net catches it for you, and sleepiness affecting watchkeeping duties is a safety matter, not paperwork.
2. Book the study in week one. Polysomnography, respiratory polygraphy or a home sleep apnoea test, whichever your system uses.
3. Start treatment and log from day one. The review should read a full compliance download, not a fortnight of it.
4. Fix the shipboard conditions by month two. Berth, spares, crew and Master informed, agreed in writing while ashore.
5. Bring the data, not the story. Six-monthly assessments read the machine recording, so the recording is your evidence.

This sleep apnea seafarers medical fitness certificate route has no waiver in it. A UK seafarer found unfit or restricted receives an ENG3 Notice of Failure or Restriction, then has one month to request referral to an MCA Independent Medical Referee. The referee's decision is final. Ireland routes appeals through an independent medical referee appointed by the Department of Transport. Anyone coached by an American page will spend that month hunting a mechanism that does not exist.

What a Nasal Stent Can and Cannot Do for Your Certificate

Straight answer: a nasal airway stent cannot satisfy a maritime CPAP compliance requirement. The regulation is written around a downloadable machine recording, so any treatment producing no adherence data cannot generate the evidence your examiner must read. The same limitation applies to a mandibular advancement device, an oral appliance and positional therapy. This is a rule about data, not efficacy.

The evidence is real and narrow. In a prospective study of 71 patients with mild-to-moderate OSA (AHI 5 to 20 on polysomnography), a nasal airway stent significantly improved AHI, supine AHI, respiratory disturbance index (RDI), oxygen desaturation index (ODI) and snore volume (p < 0.001 for AHI), with 25% showing a complete AHI response and 10% a partial response at one month (Ohtsuka et al., Respiration, 2021). Around 30% did not tolerate it.

Back2Sleep is a CE-certified Class I soft silicone intranasal stent that keeps the nasal airway open during sleep, sold without a prescription, with four sizes in the starter kit. Its shipboard advantages are specific: no mains or 24 V power, no distilled water, no tubing, no mask noise in a two-berth cabin, nothing needing a spare. It suits the seafarer who snores badly and disturbs a shared cabin without having a diagnosis.

It is not a route to a sleep apnea seafarers medical fitness certificate, and it does not treat severe OSA. For a fuller picture, read our guide to sleep apnea alternatives to CPAP with evidence behind them.

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