Flag Signal Equipment

What sets flag signal equipment apart

Flag signalling predates radio and remains in the toolkit because it needs no power, no shared electronic system and no common language: a hoist of the International Code of Signals means the same thing whether read from a Panamanian bulk carrier or a Norwegian coastguard vessel. It is slower and shorter-range than VHF, useless in poor visibility, and limited to a fixed vocabulary, so it complements rather than replaces electronic communication. Single-letter flags such as Alfa, Oscar or Whiskey are still hoisted in situations where instant, unambiguous visual recognition matters, for example a diving operation or a vessel not under command.

Main components

Flag set

A complete set covers the 26 alphabet flags, 10 numeral pennants, 3 substitute or repeater flags, and the answering pennant, made from synthetic bunting that holds its shape and colour in wind and UV exposure.

Halyards and hoist points

Flags are bent onto signal halyards run through blocks on the signal yard or mast, allowing several flags to be hoisted together as one string to build a multi-flag signal.

Code book / ICS reference

The International Code of Signals publication itself, kept on the bridge, gives the meaning of single-flag, two-flag and three-flag hoists and the procedure words used with them.

Storage

Flags are kept in a signal locker or dedicated flag bag with separate compartments per flag so a full hoist can be built quickly without sorting through a jumbled bag.

Selection and sizing

• Flag size: chosen by mast height and expected viewing distance, larger vessels carry larger sets so a hoist is legible from further off.
• Bunting quality: colourfast, low-stretch synthetic material holds up to UV and salt far better than cotton or low-grade polyester.
• Completeness: a set missing even one alphabet flag or numeral pennant cannot build every required signal, which matters for statutory carriage requirements.

Regulations and class

Carriage of an International Code of Signals flag set is a SOLAS Chapter V requirement for ships on international voyages, checked at survey alongside other navigational equipment. There is no periodic testing regime comparable to lifesaving gear, but flags are inspected for completeness, condition and legibility of colour, since a faded or torn flag can be misread as a different letter.

Typical faults

What to look for in a supplier

• Bunting fabric rated for marine UV and salt exposure, not a generic promotional flag material.
• Correct dimensions and proportions per the International Code of Signals specification.
• Complete sets sold with a proper storage bag, not loose flags.

Keep the code flags in numbered locker slots that mirror the flag bag layout, so a hoist can be built under pressure without reading every flag to identify it.