The Four Notice Types — What They Are and When They Apply
The MCA publishes four categories of notice. An examiner will test whether you know not just their names, but their legal weight and practical purpose.
Merchant Shipping Notices (MSNs) MSNs contain mandatory requirements. They have statutory force because they are cited within Statutory Instruments — the Merchant Shipping Regulations. Failure to comply is a legal offence. MSN 1858 is a key example: it sets out the mandatory requirements for the coding of small commercial vessels and yachts. When an examiner asks what makes an MSN different from the others, the answer is simple — it is law.
Marine Guidance Notes (MGNs) MGNs contain official guidance, recommendations and best practice. They are not mandatory, but they represent the MCA's interpretation of how statutory requirements should be met. Ignoring relevant guidance in an MGN will not automatically make you criminally liable, but it may be used as evidence of negligence. Think of them as the MCA telling you how to comply.
Marine Information Notes (MINs) MINs are short-life administrative notices. They carry no legal weight and contain no guidance on compliance. Typical content includes temporary information, changes to fees, contact details, or consultation exercises. They have a defined expiry and are not archived permanently. Think of them as official memos.
Notices to Mariners (NtMs) These are entirely distinct from the MCA series above. Notices to Mariners are issued by the United Kingdom Hydrographic Office (UKHO), not the MCA. Their purpose is to keep navigational charts and publications up to date — new wrecks, buoy relocations, depth changes, corrections to Admiralty charts. They carry no manning or safety management obligations. A Weekly Notice to Mariners updates charts; an MSN updates your obligations.
The Critical Distinction
| Type | Issuing Body | Legal Force | Purpose |
|---|---|---|---|
| MSN | MCA | Mandatory | Statutory requirements |
| MGN | MCA | Advisory | Guidance on compliance |
| MIN | MCA | None | Temporary information |
| NtM | UKHO | N/A | Chart & publication corrections |
An examiner will probe whether you confuse NtMs (navigational) with MCA notices (regulatory). They are produced by different bodies and serve entirely different functions. Equally, conflating an MGN with an MSN — treating guidance as optional when it is actually law — is a common and costly mistake.