The OOW (Unlimited) Certificate — Free OOW Unlimited Lesson

Prerequisites

This lesson opens the Officer of the Watch (Unlimited) course. It assumes you already understand how UK seafarer certification works in outline: what a Certificate of Competency (CoC) is, what STCW means, and why an ENG1 medical and the STCW basic safety courses come first. If you have followed the professional pathway lessons, including the Officer of the Watch (Yachts less than 3000gt) lesson, you have everything you need.

You do not need to hold any certificate to read this lesson. It is written for three kinds of reader:

A school leaver or career changer thinking about a deck cadetship.
A deck rating, or a yacht deckhand or bosun, with several years at sea who wants to become an officer.
A yacht officer who already holds the OOW (Yachts less than 3000gt) CoC and wants the unlimited certificate to work on the largest yachts or move into merchant ships.

Learning Objectives

By the end of this lesson you will be able to:

Explain what the OOW (Unlimited) CoC is, which STCW regulation it is issued under, and what it allows you to do.
Describe the three routes to the certificate in MSN 1856: the cadetship, the experienced seafarer route and the conversion for OOW (Yacht) holders.
State the sea service requirements, including the six months of bridge watchkeeping duties, and explain how service is proved.
List the safety and ancillary courses that must be held, and say which need updating every five years.
Describe the written examinations, the changes made by MIN 720 for students starting from August 2025, and the MCA oral examination.
Compare the unlimited and yacht ladders and explain why a large-yacht officer might choose the unlimited route.
Draw up a realistic plan, in time and money, for your own route.

What the Certificate Is

The OOW (Unlimited) CoC is the UK certificate issued under STCW Regulation II/1: officer in charge of a navigational watch on ships of 500 gross tonnage or more. "Unlimited" means there is no tonnage limit and no area limit. The same certificate lets you keep the bridge watch on a 300,000 tonne crude carrier, a container ship, a cruise ship, a cable layer or a 120 m motor yacht.

It is an operational level certificate. The STCW Code (Table A-II/1) sets out what you must be competent in, grouped into three functions:

Navigation at the operational level: passage planning and position fixing, keeping a safe navigational watch, using radar, ARPA and ECDIS, responding to emergencies and distress signals, using the IMO Standard Marine Communication Phrases, transmitting and receiving by visual signalling, and manoeuvring the ship.
Cargo handling and stowage at the operational level: monitoring loading, stowage, securing and care of cargo during the voyage and unloading.
Controlling the operation of the ship and care for persons on board at the operational level: stability, trim and stress, pollution prevention (MARPOL), fire fighting, life-saving appliances, medical first aid, legislation, leadership and teamwork.

The next steps up the same ladder are Chief Mate (Unlimited), STCW II/2, and Master (Unlimited), also II/2. Those are management level certificates.

Why yacht officers care

The yacht certificates (OOW, Chief Mate and Master (Yachts less than 3000gt)) are excellent qualifications, but they stop at 3000 GT and are valid on yachts only. The largest yachts are now well over 3000 GT, and they need officers holding unlimited certificates. An unlimited certificate is also accepted on yachts of any size, so it never closes a door. That is why so many experienced yacht officers convert, and why some young crew choose a merchant cadetship first and move to yachts later.

The Rules: MSN 1856

The UK requirements are in MSN 1856 (M+F) Amendment 1, UK requirements for masters and deck officers. It implements STCW through the Merchant Shipping (Standards of Training, Certification and Watchkeeping) Regulations 2022. Section 3.2 of MSN 1856 lists what you need for an OOW (Unlimited) CoC:

Be at least 18 years of age.
Have the required seagoing service since the age of 16 (it depends on your route, see below), including six months on bridge watchkeeping duties.
Hold the safety and ancillary course certificates listed in section 10.
Complete an MCA-approved education and training programme that meets section A-II/1 of the STCW Code.
Hold a Signals certificate issued within the previous three years.
Pass the MCA OOW safety examinations in Navigation and in Stability and Operations at an approved exam centre (or hold an exemption).
Hold a valid ENG1 medical certificate or an accepted equivalent.
Pass the MCA oral examination.

The written exams and the oral must have been passed within the three years before the CoC is issued. If you pass the oral and then take four years to send in the application, you will have to sit them again.

The Three Routes

The diagram below shows the three ways in, and the requirements that everyone must meet at the end.

Three routes to the OOW (Unlimited) CoC: cadetship, experienced seafarer and OOW (Yacht) conversion, joining common requirements

Route 1: the cadetship

A cadetship is the standard route for new entrants. You are accepted onto an MCA-approved programme at a UK nautical college, usually sponsored by a shipping company or a training provider that places you on its ships. The academic award is an HND, a Foundation Degree (FD), an Honours Degree or, in Scotland, a Scottish Professional Diploma (SPD). The programme alternates college phases with sea phases and typically lasts about three years.

The sea service is shorter than on the other routes because the training at sea is structured and recorded:

12 months of approved seagoing service as part of the approved programme, documented in an MCA Training Record Book (TRB) that shows each task signed off on board.
Six months of that service must be on bridge watchkeeping duties.
Up to two months of full-mission bridge simulator training can be credited towards the sea service on a UK cadetship (MSN 1856 section 9 and Annex F).
You need a letter from your college confirming you are on the programme. You send it with your application for a Notice of Eligibility.

Cadets on an approved FD, Honours Degree or SPD can be exempt from the MCA written examinations if they reach the required marks in the degree: an overall average of at least 50%, with at least 65% in Navigation and 60% in Stability and Operations. Students who do not reach those marks must sit the papers they failed to reach. Cadets also cover HELM (Operational) within the programme and need no separate certificate for it.

There is also an approved overseas collaborative programme ("one plus one"), overseen by a UK college. The college letter states the sea service required for that programme.

Route 2: the experienced seafarer route

If you are a deck rating, a fisherman or a crew member with long sea service, you can use the experienced seafarer route:

36 months of seagoing service since the age of 16, of which six months on bridge watchkeeping duties.
Service must be on merchant ships of at least 24 m registered length or 80 GT, proceeding to sea (beyond UK categorised waters, or beyond harbour limits abroad). Service on ships of any flag counts.
You then apply to an MCA-approved nautical college for the approved education and training programme (at HNC level for this route), complete the short courses, and sit the written and oral exams.

You do not need a college letter to get a Notice of Eligibility on this route, but you do need the college's acceptance to study.

Route 3: the OOW (Yacht) conversion

Section 13.3 of MSN 1856 gives holders of an OOW (Yachts less than 3000gt) II/1 CoC a direct route to the unlimited certificate. You must:

Complete 36 months on yachts of more than 24 m registered length or at least 80 GT, with evidence of at least six months on bridge watchkeeping.
Hold a certificate showing completion of the "Underpinning Knowledge for OOW certification" (the HNC listed in section 11.4).
Hold the safety and ancillary courses in section 10, and a Signals certificate from the last three years.
Pass the MCA OOW written exams in Navigation and in Stability and Operations.
Hold a valid ENG1 and pass the MCA oral.

The HNC is the big step. It brings in the merchant ship knowledge the yacht syllabus leaves out: cargo work, ship stability at full scale (large free surface effects, shear force and bending moment), ship construction, MARPOL and merchant ship law.

Sea Service: What Counts and How to Prove It

Sea service is usually the slowest part of any route, so it pays to understand the counting rules early.

The basic definitions

Seagoing service is service on a ship relevant to the certificate, counted from the date of joining to the date of leaving.
Bridge watchkeeping duties (for an OOW II/1 application) means duties on the bridge under the supervision of the master or a qualified officer. MSN 1856 section 9.5 says these duties may include keeping a lookout on the bridge or acting as helmsman. You need a statement from the master confirming at least six months.
Watchkeeping service (needed later for Chief Mate and Master) means time as the duty officer in full charge of a navigational watch for at least 4 hours in every 24 while on a voyage. Do not confuse it with bridge watchkeeping duties.

Allowances

For certificates needing at least 12 months of sea service, MSN 1856 allows up to two months of each of the following:

Standing by a new ship in the final stages of building, or in dry dock, or under repair.
For a UK cadetship's first CoC, full-mission bridge simulator training.
For unlimited certificates, up to one month on vessels of 24 m or 80 GT or more operating in categorised C and D waters.

Yacht service

Yacht service of 24 m or 80 GT and above counts in full towards an unlimited II/1 or II/2 certificate (MSN 1856 Annex F), but it is counted as a mix of three kinds:

Actual seagoing service: the yacht at sea.
Standby service: in port, between voyages, with you on board ready to sail. Standby counted after a voyage may not exceed the length of that voyage, and never more than 14 days in each period. So you can never count more standby than actual sea time.
Yard service: refit time. A maximum total of 90 days counts for the OOW certificate (30 days for Chief Mate or Master).

Yacht service is proved on yacht service testimonials that break the time down into actual, standby and yard days (see MSN 1858).

Proof

Proof is by discharge book entries or certificates of discharge, supported by testimonials signed by the master covering conduct, ability and the service performed. Keep a running record yourself: dates, vessel names, IMO or official numbers, GT, length, and the voyages. Testimonials are far easier to get signed before you leave a ship than two years later by email.

Worked example: counting a yacht deckhand's time

Sam has been a deckhand and then bosun on two yachts, both over 24 m:

Period	Actual sea	Standby claimed	Yard
Year 1 (55 m yacht)	120 days	95 days	60 days
Year 2 (55 m yacht)	140 days	110 days	50 days
Year 3 (72 m yacht)	150 days	120 days	40 days

Sam's standby is less than the actual sea time each year, but each claim must also respect the 14-day cap per period and the "no longer than the previous voyage" rule, so the testimonials must be broken down voyage by voyage. The yard time totals 150 days, but only 90 days count towards the OOW certificate. If all the standby is valid, Sam has 410 actual + 325 standby + 90 yard = 825 days, about 27 months. Sam is still about nine months short of 36 months and must also show six months of bridge watchkeeping duties (for example, as bridge lookout and helmsman on passage watches). A careful count like this, done early, stops a wasted application.

The Courses You Must Hold

The table in MSN 1856 section 10 lists the safety and ancillary courses. The diagram groups them.

Safety and ancillary certificates needed for an OOW (Unlimited) CoC, with those needing five-yearly updating marked

Safety courses (STCW Chapter VI)

STCW basic safety training: Personal Survival Techniques (PST), Fire Prevention and Fire Fighting (FPFF), Elementary First Aid (EFA) and Personal Safety and Social Responsibilities (PSSR). These four are usually taken together in about a week, and most people take them before their first trip to sea.
Proficiency in Survival Craft and Rescue Boats (PSCRB): launching and handling lifeboats, liferafts and rescue boats.
Advanced Fire Fighting (AFF): leading fire parties and controlling fire fighting.
Medical First Aid (MFA): the level expected of the person who gives first aid on board. (Medical Care is the higher course, needed for Chief Mate and Master.)

PST, FPFF, PSCRB and AFF need updating every five years. You must show evidence of the course or its refresher within the last five years for every CoC application, and Port State Control will expect to see it on board.

Ancillary courses (MCA approved)

NAEST (Operational): Navigation Aids, Equipment and Simulator Training. Radar, ARPA, AIS and the conduct of simulated watches in traffic and restricted visibility, applying the COLREGs. If you took NAEST (O) after July 2005 it covers the ECDIS knowledge STCW requires; if not, you must take a standalone ECDIS course.
ECDIS: the generic IMO Model Course 1.27 style course. On board, each ship's ECDIS type also needs type-specific familiarisation, which the company arranges.
HELM (Operational): Human Element, Leadership and Management at the operational level. Teamwork, situational awareness, communication, fatigue, decision making.
Efficient Deck Hand (EDH): practical seamanship, mooring and anchoring, cargo gear, pilot ladders and means of access, safe working practice. It requires a minimum period of sea service before you can sit the practical assessment (check MSN 1862 for the current figure).
GMDSS General Operator's Certificate (GOC): the full radio operator's certificate for ships sailing in all sea areas. It must carry an STCW endorsement.

Also needed

Signals certificate: issued within the last three years. It tests the International Code of Signals, flag and light signalling and the IMO Standard Marine Communication Phrases.
ENG1 medical certificate, valid (normally for two years).

Rule of thumb on ordering

Take STCW basic safety and ENG1 before you go to sea. Take EDH and PSCRB once you have the sea time they require. Leave NAEST (O), GMDSS GOC and ECDIS until you are studying for the exams, so that the learning is fresh when you sit them. But do not leave the five-yearly refreshers until the month you apply: one expired certificate stops the whole application.

The Examinations

The written examinations

The MCA OOW safety examinations are two papers, sat at an approved exam centre:

Navigation: chartwork, tides, passage planning, celestial and electronic navigation, compass work, meteorology, COLREGs applied, and the use of navigation equipment.
Stability and Operations: ship stability (GM, free surface, list, trim, the effects of loading), ship construction, cargo work, and safety and pollution prevention operations. The MCA publishes the syllabus online.

For students who started their programme before August 2025, these are written exams administered by Qualifications Scotland (the body that replaced the SQA, which ran them for many years). Students enrolled on an approved FD or degree before August 2025 keep their exemption from them until September 2029.

MIN 720: the modernised syllabus

MIN 720 (M) Amendment 1 sets out the biggest overhaul of the UK officer syllabus in many years, produced by the MCA's Cadet Training and Modernisation Programme. From August 2025, all new OOW (Unlimited) course starters:

follow a modernised syllabus that goes beyond the STCW minimum, with up-to-date practice and technology, cyber security, more human element skills, and training on alternative fuels and decarbonisation; and
must pass the new MCA Deck Operational Level Digital Assessment: Navigation, Stability and Operations, Operational Level STCW Reg. II/1, which replaces the written papers for them.

If you are starting now, check with your college which version you are on, and read the current MIN, because the transitional dates are precise and can change.

The MCA oral examination

The oral is where an MCA examiner decides whether you can be trusted with the bridge. Before you can book it you need a Notice of Eligibility (NoE) from the MCA, which confirms that your sea service, courses and education meet the requirements. MIN 690 explains booking, NoEs and the online oral process; orals can be held face to face at an MCA marine office or online.

The oral syllabus is published by the MCA (MIN 653 (M) Amendment 1, and the "Oral Exam Syllabuses" section of the MCA seafarer careers web page). It is in two parts: Part A and Part B, with Part A taken online. Check the current MIN for exactly what each part covers and how they are booked. Across the two parts, expect to be examined on:

Watchkeeping: handover, standing orders, calling the master, lookout, fatigue, MGN 315.
The COLREGs, in depth: lights and shapes shown on models or cards, and collision situations explained aloud, including restricted visibility.
Use of radar, ARPA and ECDIS, including their errors and limitations.
Passage planning, pilotage, anchoring and berthing.
Emergencies: man overboard, fire, collision, grounding, flooding, abandon ship, search and rescue (IAMSAR Vol III), GMDSS distress procedures.
Stability in practice, cargo safety, pollution prevention (MARPOL, the oil record book and garbage record book), ISM, ISPS and SOLAS equipment.

The examiner is not looking for recited text. They want to hear what you would actually do, in the right order, and why. A typical question: "You have the 0000 to 0400 watch. Visibility drops to half a mile. What do you do?" A good answer goes: call the master, post an extra lookout, hand steering, start sound signals, safe speed with the engine room warned, radar on an appropriate range with plotting, fix position, and so on. Practise answering aloud with someone who has passed.

If you fail, the examiner will tell you which areas let you down, and you can re-sit after a waiting period. Check the current MIN for re-sit intervals.

Time and Money

There are no exact figures that suit everyone, but you can plan in outline.

Route	Typical time	Who usually pays
Cadetship (HND, FD, degree)	About 3 years from start to CoC	A sponsoring company usually pays fees and a training allowance
Experienced seafarer	36 months of sea service, then about a year of college and courses	Usually self-funded, sometimes by an employer
OOW (Yacht) conversion	36 months of yacht service, then the HNC (often part-time or distance learning), short courses and exams	Usually self-funded; some yacht employers help

Costs to budget for on the self-funded routes:

College fees for the HNC or equivalent.
Short courses: NAEST (O), GMDSS GOC, ECDIS, HELM (O), EDH, PSCRB, AFF, MFA and refreshers. These typically add up to several thousand pounds; get current quotes from approved colleges.
MCA fees for the NoE, the oral and issue of the CoC (check the current MCA fee list).
Travel, accommodation and lost earnings while ashore studying.

Many people on the experienced and yacht routes plan their rotation so that study blocks fall in the off-season or between contracts.

Unlimited vs Yacht: Choosing Your Ladder

The diagram compares the two ladders and shows the conversion path between them.

Unlimited and yacht certificate ladders side by side, with the OOW (Yacht) to OOW (Unlimited) conversion

On the unlimited ladder, the next step from OOW is Chief Mate (Unlimited), which needs 12 months of watchkeeping service as OOW, NAEST (Management), HELM (Management), Medical Care, and the Chief Mate written and oral exams. Master (Unlimited) then needs 36 months of watchkeeping service as OOW, reduced to 24 months if at least 12 months was served as Chief Mate.

Point	Yacht ladder (MSN 1858)	Unlimited ladder (MSN 1856)
Where valid	Yachts only, under 3000 GT	Any ship, any size, any area, including yachts
Entry knowledge	Yachtmaster Offshore plus MCA yacht courses	HNC, FD or degree level education
Cargo, large-ship stability	Not covered	Fully covered
Career options	Yacht deck officer to master	Merchant navy, offshore, cruise, large yachts, then shore careers such as pilot, harbour master, marine superintendent
Time to OOW	Often quicker for yacht crew	Longer, but wider

A yacht officer serving on unlimited ships or large yachts and wanting to climb further must, under MSN 1856 Annex F, include in their service either at least six months on yachts of 500 GT or more beyond UK categorised waters (or harbour limits abroad), or at least six months on vessels of 24 m or more on voyages of more than 300 nautical miles.

Worked Example: Planning Two Routes

Aisha, 18, leaving school. She applies to sponsoring companies and joins an FD cadetship in September. Before her first sea phase the college runs STCW basic safety and she gets her ENG1. She spends roughly a year at sea in total, split over phases, filling her TRB and gaining six months on bridge duties. She aims for 65% or more in Navigation and 60% or more in Stability and Operations, so she is exempt from the separate MCA papers (or takes the digital assessment if her course started after August 2025). Final college phase: NAEST (O), GMDSS GOC, EDH, PSCRB, AFF, MFA, Signals. She gets her NoE, passes the oral, and receives her CoC at about 21, then needs 12 months of watchkeeping as OOW before Chief Mate.

Tom, 28, former deckhand, now a yacht OOW. Tom holds OOW (Yachts less than 3000gt) and has 40 months of yacht service with good testimonials. He checks the counting: after capping yard time and standby, 37 months count, with eight months of bridge watchkeeping. He enrols on the HNC by distance learning, studies through two winters, sits the MCA written exams, renews PST and FPFF (both four and a half years old, so close to expiry), books the oral via his NoE, and passes. His new certificate lets him apply to the 4,000 GT yachts that were closed to him.

Common Mistakes

Confusing bridge watchkeeping duties with watchkeeping service. For OOW you need six months of duties on the bridge under supervision; later certificates need time as the officer in charge.
Over-claiming yacht standby and yard time. The 14-day and 90-day caps are applied strictly. Break testimonials down voyage by voyage.
Letting a five-yearly certificate expire. PST, FPFF, PSCRB and AFF must be in date at application.
Forgetting the three-year windows. Signals certificate within three years; written exams and oral within three years of CoC issue.
Studying for the oral as a memory test. The examiner asks "what would you do?" and follows up. Practise thinking aloud.
Assuming the old rules still apply. MIN 720 changed the assessments for August 2025 starters. Always read the current MSN and MIN, not a forum post.
Leaving testimonials until later. Get each one signed by the master before you leave the vessel.

Summary

The OOW (Unlimited) CoC is the UK STCW II/1 certificate for officers in charge of a navigational watch on ships of any size, in any area. It is the gateway to Chief Mate and Master (Unlimited), and it is valid on yachts of any size.
MSN 1856 Amendment 1 sets the requirements: age 18, sea service, approved education, safety and ancillary courses, Signals certificate, written exams (or exemption or digital assessment), ENG1 and an MCA oral.
Routes: cadetship (12 months approved service with a TRB), experienced seafarer (36 months), and OOW (Yacht) conversion (36 months on yachts of 24 m or more plus HNC). All need six months of bridge watchkeeping duties.
Required courses include STCW basic safety, PSCRB, AFF, MFA, NAEST (O), ECDIS, HELM (O), EDH and GMDSS GOC; four of the safety courses need five-yearly updating.
From August 2025, new starters follow the MIN 720 modernised syllabus and take the MCA Deck Operational Level Digital Assessment.
The oral needs a Notice of Eligibility and is in two parts. Expect practical, sequenced questions on watchkeeping, COLREGs, equipment, emergencies and stability.

Check Your Understanding

Under which STCW regulation is the OOW (Unlimited) CoC issued, and at what level?

Answer: STCW Regulation II/1, officer in charge of a navigational watch on ships of 500 GT or more. It is an operational level certificate.

What sea service does a cadet need, and how is the onboard training recorded?

Answer: At least 12 months of approved seagoing service as part of an MCA-approved cadet programme, including six months on bridge watchkeeping duties, recorded in an approved Training Record Book.

A deck rating has 30 months of service on merchant ships. Can they use the experienced seafarer route yet?

Answer: No. The route needs 36 months of seagoing service since the age of 16, including six months on bridge watchkeeping duties.

A yacht officer claims 120 days of yard time in their application. How much counts towards the OOW (Unlimited) certificate?

Answer: A maximum of 90 days of yard service counts towards OOW.

Name four safety courses that must be updated every five years.

Answer: Personal Survival Techniques, Fire Prevention and Fire Fighting, Proficiency in Survival Craft and Rescue Boats, and Advanced Fire Fighting.

What is the difference between "bridge watchkeeping duties" and "watchkeeping service"?

Answer: Bridge watchkeeping duties (needed for OOW) are duties on the bridge under the supervision of the master or a qualified officer, which can include lookout and helmsman. Watchkeeping service (needed for Chief Mate and Master) is time as the duty officer in full charge of a navigational watch, at least 4 hours in every 24 on a voyage.

What changed for OOW (Unlimited) students starting in August 2025?

Answer: Under MIN 720 they follow a modernised syllabus (including cyber security, human element skills and alternative fuels) and must pass the new MCA Deck Operational Level Digital Assessment in Navigation, Stability and Operations instead of the old written papers.

What document must you hold before you can book the MCA oral?

Answer: A Notice of Eligibility (NoE) from the MCA, confirming that your service, courses and education meet the requirements.

You passed the MCA oral three and a half years ago but never applied for the CoC. What happens?

Answer: The exams and oral must be passed within the three years before the CoC is issued, so you would have to pass them again.

Give two reasons a large-yacht officer might convert to the unlimited certificate.

Answer: The yacht certificates are limited to yachts under 3000 GT, so yachts above that size need unlimited officers; and an unlimited certificate is valid on any ship, opening merchant, offshore and later shore-based careers.

The OOW (Unlimited) Certificate: Routes, Sea Service and Exams