ENG1 vs ML5 vs OGUK/OEUK Medical: Which One Do You Need?
Three different seafarer and offshore medicals, often confused. Here is how to tell which one your role actually requires.
- The ENG1 is the statutory seafarer medical for seagoing ships; it is issued only by MCA-approved doctors and is recognised internationally.
- The ML5 is a lighter, UK-only medical for crew of small commercial vessels operating within about 60 miles of a safe haven; it can usually be done by any GP and is valid for up to 5 years.
- The OEUK medical (formerly OGUK) is an offshore energy industry medical for workers travelling to installations; it is valid for up to 2 years.
- A valid ENG1 can be used in place of an ML5, but an ML5 cannot replace an ENG1.
- A person who both crews a vessel and travels offshore may need both an ENG1 and an OEUK certificate.
- Rule of thumb: going to sea on a ship needs an ENG1; a small boat close to the UK shore may only need an ML5; flying offshore to an energy installation needs an OEUK medical.
Quick comparison
| ENG1 | ML5 | OEUK / OGUK | |
|---|---|---|---|
| For | Crew on seagoing ships, superyachts, cruise ships | Crew of small commercial vessels within ~60 miles of a safe haven | Workers travelling offshore to energy installations (oil, gas, wind) |
| Set by | MCA (statutory, MLC / MSN 1886) | MCA (for restricted domestic operations) | Offshore Energies UK (industry standard) |
| Who can issue | MCA-approved doctor only | Often any registered GP | OEUK-registered doctor |
| Validity | Up to 2 years (1 year if 16–18) | Up to 5 years | Up to 2 years |
| Recognition | International | UK only | UK offshore energy sector (and widely accepted internationally offshore) |
| Typical cost | Up to £115 (capped) | ~£60–£115 | ~£140–£220 |
When you need an ENG1
If you are joining a seagoing merchant ship, a superyacht, a cruise ship, or starting an STCW course or cadetship, you need an ENG1. It is also the safe default — an ENG1 can be used in place of an ML5, but an ML5 cannot stand in for an ENG1.
When an ML5 is enough
The ML5 is designed for masters and crew of small commercial vessels — workboats, small passenger boats, sail-training vessels — operating in UK inshore waters (Area Categories 2–6, up to about 60 miles from a safe haven). It is a lighter assessment and does not carry the colour-vision and full fitness requirements of the ENG1. It is not accepted for deep-sea or international voyages.
When you need an OEUK / OGUK medical
If your job takes you offshore by helicopter to an oil or gas platform, a drilling rig or an offshore wind installation, you will almost certainly need a current OEUK medical (still often called "OGUK"). It focuses on fitness for a remote environment with limited medical access, and often includes spirometry and a Chester Step test. Many offshore workers who also hold a seafarer role carry both an ENG1 and an OEUK certificate.
Not sure which you need?
As a rule of thumb: going to sea on a ship → ENG1; small boat, close to UK shore → ML5 may do; flying offshore to an energy installation → OEUK. If your employer or agency has told you which certificate to bring, follow that.
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