When Is a Ship Legally Required to Adjust Its Magnetic Compass? SOLAS Chapter V Explained

Of all the words in SOLAS Chapter V, two do a surprising amount of work: properly adjusted. The convention does not merely require a ship to carry a magnetic compass — it requires a properly adjusted one. That single phrase turns compass adjustment from a piece of good seamanship into a standing legal obligation, and it is the reason a vessel can pass every other check yet still pick up a Port State

Control deficiency over a compass nobody has touched in years.

This guide sets out exactly what the rules say, when a compass must be adjusted, who enforces it, and where the responsibility sits. It is written for the people who actually carry the obligation — owners, fleet managers, DPAs, and masters — rather than as a textbook on magnetism. If you want the underlying concepts of deviation and variation first, our explainer on True North versus Magnetic North covers those.

What SOLAS Chapter V actually requires

The core rule lives in SOLAS Chapter V, Regulation 19 — the carriage requirements for shipborne navigational systems and equipment. In paragraph 19.2.1.1 it requires every ship, irrespective of size, to be fitted with:

a properly adjusted standard magnetic compass, or other means, independent of any power supply, to determine the ship's heading and display the reading at the main steering position.

Two things matter in that wording. First, it is power-independent — the magnetic compass is the navigational fallback that still works when everything electronic has failed, which is precisely why regulators refuse to let it lapse. Second, it is properly adjusted — not simply present, but corrected so that its error is known and within acceptable limits.

Regulation 19 goes further. Alongside the standard compass it requires a means of taking bearings over a full 360° (a pelorus or compass bearing device) and a means of correcting heading and bearings to true at all times — in practice, a current deviation table. Ships of 150 gross tonnage and upwards engaged on international voyages must additionally carry a spare magnetic compass interchangeable with the standard one (or an approved transmitting heading device).

Supporting this, IMO Resolution A.382(X) — the long-standing recommendation on magnetic compasses — states that every compass should be properly compensated and that the table or curve of residual deviations must be kept available on board in the vicinity of the compass at all times. So the deviation card is not paperwork for the filing cabinet; the law expects it at the binnacle.

When must the compass actually be adjusted?

This is the question that catches operators out, because "properly adjusted" has no meaning without knowing when re-adjustment is due. The widely applied benchmark is ISO 25862:2019 (the current international standard for marine magnetic compasses, which superseded the older ISO 449 and ISO 2269), reinforced by flag-state and classification guidance. Taken together, a ship's magnetic compass should be swung and adjusted when any of the following occurs:

• It is first installed on a new or re-fitted vessel.

• It becomes unreliable — the deviation is erratic or the readings can no longer be trusted.

• The deviation becomes excessive — once residual deviation consistently exceeds the accepted limit (commonly cited around 5° on any heading), adjustment is due.

• After dry-docking, structural repairs, or alterations that could change the ship's permanent or induced magnetism — welding, hull work, and steelwork all disturb a vessel's magnetic signature.

• When electrical or magnetic equipment near the compass is installed, removed, or altered — new electronics on the bridge can shift deviation overnight.

• At a defined interval regardless of the above — ISO 25862:2019 calls for adjustment no less than every two years, and many administrations and operators apply a shorter cycle or require the deviation to be checked far more frequently (often each watch at sea, and after major course changes).

• Whenever the master considers it necessary — the master's judgement is explicitly a valid trigger.

The practical takeaway: there is no single universal date. A compass that has had a quiet two years still falls due on the interval; a compass on a vessel that just left dry dock falls due immediately, no matter how recently it was last done. Owners who track only the calendar, and forget the event-based triggers, are the ones who get caught out.

A point worth stressing for multi-flag fleets: SOLAS and ISO set the floor, but the flag state administers it, and individual flags or classification societies may impose stricter intervals or documentation. A flag state such as Liberia (LISCR), for example, administers the SOLAS V/19 carriage requirements for vessels on its register. Always check the specific flag's marine notices alongside the international baseline.

Who enforces it — and what happens if you don't comply

Three layers of enforcement sit behind that phrase "properly adjusted":

Flag state. Your flag administration sets and surveys the requirement as part of the vessel's safety equipment certification. A compass without a current deviation table is a finding against the ship's certificate.

Port State Control. This is where non-compliance most often bites. PSC inspectors routinely check that the magnetic compass is adjusted and that a current table or curve of residual deviations is available at the compass. A missing, outdated, or implausible deviation card can be recorded as a deficiency — and in the wrong combination with other findings, deficiencies are what escalate an inspection toward detention.

Class and the safety case. Classification surveys and a company's own safety-management system (under the ISM Code) both expect compass adjustment records to be current and auditable.

None of these are exotic edge cases. The magnetic compass and its deviation card are standard inspection items precisely because the compass is the last-resort heading reference. The cost of compliance is small; the cost of a detention, a delayed sailing, or a navigational incident traced to an uncorrected compass is not.

The catch hidden in "properly adjusted": who is allowed to do it?

Here is the part operators most often underestimate. SOLAS requires the compass to be properly adjusted — and adjustment is a skilled, technical task, not something to be improvised. It involves measuring the ship's magnetism, positioning correctors (fore-and-aft and athwartship magnets, soft-iron spheres, the Flinders bar, heeling magnet), swinging the ship, and producing a residual deviation table that will stand up to inspection. Guidance and most administrations expect this to be carried out by a competent, qualified compass adjuster; where a qualified adjuster is genuinely unavailable, a master may act only if he or she has the necessary expertise.

That single requirement is what drives the real-world choice every fleet eventually faces: keep paying external adjusters port by port, or have a qualified officer on your own crew who can do it. (We will cover the "who is authorised to adjust" question, and the in-house-versus-external cost case, in upcoming posts.)

If the answer for your fleet is to build that capability in-house, that is exactly what a formal qualification provides. The Magnetic Compass Adjuster course at Elite Offshore Academy is an ABS Class-approved, TUV NORD ISO 21001-certified, hands-on programme that trains an officer to carry out compliant adjustments and produce the deviation table SOLAS expects — turning a recurring outsourced cost into an onboard competence.

A quick compliance checklist for owners and masters

Run your vessel against this:

1. Is there a properly adjusted standard magnetic compass at the main steering position?

2. Is a current table or curve of residual deviations physically available at the compass — not just in the office?

3. Has the compass been adjusted within the interval (ISO 25862:2019 baseline of two years, or shorter if your flag/operator requires)?

4. Has it been re-adjusted after the last dry-docking, structural work, or change of bridge equipment?

5. For vessels 150 GT and over on international voyages — is there a compliant spare compass (or approved transmitting heading device)?

6. Are adjustment dates and details recorded in the compass log / SMS?

Any "no" is a compliance gap worth closing before the next survey or PSC inspection.

The bottom line

SOLAS Chapter V does not ask ships to carry a magnetic compass; it requires a properly adjusted one, backed by a current deviation table kept at the compass and re-adjusted both on a regular interval and after any event that disturbs the ship's magnetism. The obligation is continuous, the enforcement is real, and the task itself must be done competently. For operators, the strategic question that follows is simply who does that work — and whether it is time to build the capability into your own crew.

If that is the direction you are weighing, you can see how an officer becomes qualified to do it on the Magnetic Compass Adjuster course page.

Frequently asked questions

Is a magnetic compass still mandatory if a ship has GPS and a gyro compass?

Yes. SOLAS Chapter V, Regulation 19 requires a properly adjusted standard magnetic compass independent of any power supply, precisely so the vessel retains a heading reference when electronic and powered systems fail. GPS and gyro do not remove the requirement.

How often must a ship's magnetic compass be adjusted?

ISO 25862:2019 sets a baseline of at least every two years, plus adjustment after dry-docking, structural work, or any change that affects the ship's magnetism — and whenever deviation becomes excessive or the master deems it necessary. Some flag states and operators apply shorter intervals, so check your flag's requirements.

Does the deviation card have to be on the bridge?

Yes. IMO Resolution A.382(X) requires the table or curve of residual deviations to be available on board in the vicinity of the compass at all times — at the binnacle, not filed away in the office.

What happens if the compass is not properly adjusted?

It can be recorded as a deficiency in a Port State Control inspection and counts against the vessel's safety equipment certification. Combined with other findings, it can contribute to detention, besides the underlying navigational safety risk.

Can the ship's master adjust the compass, or does it need a qualified adjuster?

Adjustment is expected to be carried out by a competent, qualified compass adjuster. A master may do it only if a qualified adjuster is genuinely unavailable and the master has the necessary expertise — which is why many operators choose to formally train an officer for the role.