A ship calling at a Brazilian port can have its magnetic compass adjusted during the call. The work is done by a qualified compass adjuster and usually takes a few hours, including the swing. It is worth scheduling when the deviation card is out of date, after dry-docking or structural work, after changes to equipment near the binnacle, or when the observed deviations no longer match the card. SOLAS requires every ship to carry a properly adjusted standard magnetic compass. Port State Control officers and vetting inspectors routinely check the compass, the deviation card and the compass error records. This guide explains the requirement, the usual triggers, what to send in advance, and what you should receive afterwards.
This guide summarizes public rules as of October 2026. It is not legal advice. Check the current SOLAS text, your flag state's requirements and the local Capitania dos Portos (Harbour Master's Office) before planning.
What SOLAS requires
SOLAS Chapter V, regulation 19, sets the carriage requirements for navigational equipment. For all ships, whatever their size, paragraph 2.1 requires:
- 2.1.1: "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";
- 2.1.2: a pelorus or compass bearing device, or other means independent of any power supply, to take bearings over 360° of the horizon;
- 2.1.3: "means of correcting heading and bearings to true at all times".
Ships of 150 gross tonnage and upwards must also carry a spare magnetic compass, interchangeable with the standard compass, or another means of performing the same function (paragraph 2.2.1).
The magnetic compass is the ship's heading reference that works without power. Gyro compasses and GNSS-based heading sensors do not replace it. Paragraph 2.1.3 means the bridge must always be able to apply variation and deviation, which in practice depends on a current deviation card.
SOLAS does not set the adjustment interval. Flag states, classification societies and industry standards such as ISO 25862 each give their own guidance. Check your flag state's rules and your company's Safety Management System procedures for the interval that applies to your ship.
Compensation, adjustment and the deviation card
The terms are often used loosely, so it helps to be precise:
- Compensation reduces the effect of the ship's own magnetism on the compass. The adjuster positions corrector magnets, quadrantal spheres and the Flinders bar in the binnacle.
- Adjustment usually means the full job: compensation, followed by a swing on several headings to measure the deviations that remain.
- Deviation card (or curve) records the residual deviation on each heading after adjustment. It is posted near the compass and used to correct headings and bearings.
In Brazil, compass adjusters (peritos) are qualified through the Brazilian Navy. The Directorate of Hydrography and Navigation (DHN) runs a specific course on compass compensation. Brazil renumbered its Maritime Authority standards (NORMAM) in 2023. If a document quotes an older NORMAM number for compass adjusters or certificate validity, confirm the current reference with the Capitania before relying on it.
When to adjust
Plan an adjustment when any of the following applies:
- The deviation card has expired under your flag state or company procedures.
- After dry-docking or major repairs, especially hull or superstructure steelwork near the bridge.
- After structural changes, such as new deckhouses, masts, cranes or other steel close to the compass.
- After electrical or equipment changes near the binnacle, such as new cabling, loudspeakers, radar units, consoles or DC circuits.
- After magnetic cargo or a long period on one heading, for example steel cargo, a long lay-up alongside, or a long tow on a steady heading. These can change the ship's induced magnetism.
- When observed deviations differ from the card, as found in routine compass error checks against gyro, transit or azimuth bearings.
- After a large change in magnetic latitude or trade area, because induced magnetism changes with latitude and the Flinders bar and spheres may need checking.
- Before an inspection or vetting, if the records show the compass is no longer reliable.
Brazil's long coastline and its trade with both hemispheres mean many ships arrive after a large change in magnetic latitude, so an adjustment during a Brazilian call is common.
What to send in advance
Sending these details with the request lets the adjuster plan the swing and estimate the time needed:
- Ship name, IMO number, type, flag and gross tonnage.
- Port, berth or anchorage, and expected arrival and departure times.
- Current deviation card and the date of the last adjustment.
- Recent compass error records from the deck log or compass error book.
- Make and model of the standard compass, the spare compass and the binnacle.
- Details of recent dry-docking, repairs, new equipment or cargo that could affect the compass.
- Any known defects: a bubble in the bowl, a sticking card, damaged lighting, or missing correctors.
- Whether the ship can manoeuvre for a swing, and whether a pilot, tug or anchorage slot is needed. Swings are often done on departure or in a designated area. Confirm the local arrangements with the agent and the Capitania.
What you should receive
Deliverables vary by adjuster and flag state, so agree on them before the work starts. Typically they include:
| Deliverable | What it contains |
|---|---|
| Deviation card or curve | Residual deviation on each heading after adjustment, with date, position and adjuster's signature |
| Adjustment certificate or report | Ship details, compass details, corrector positions, method used and any findings |
| Maintenance notes | Condition of the bowl, card, lighting, binnacle and correctors, with recommendations |
Keep the signed originals on board and send copies to the technical department. If the adjuster finds a fault that cannot be fixed during the call, ask for it to be written in the report so it can be planned for the next port or dry-dock.
Aneroid barometer calibration
Many ships book barometer calibration during the same call. The aneroid barometer is used for weather observation and logbook entries, and a drifting barometer gives misleading pressure trends. A calibration compares the instrument with a reference standard across its range. A calibration certificate typically states:
- instrument make, model and serial number;
- measuring range and the tolerance or accuracy achieved;
- the method and reference standard used;
- the readings and corrections found;
- the calibration date and a recommended validity or recalibration date.
Safe Offshore handles magnetic compass adjustment and barometer calibration for ships calling at Vitória and other Espírito Santo ports. Booking both together saves time during short calls.