2182 kHz

[4] The reception range of even a well-equipped station can be severely limited in summer because of static caused by lightning.

Historically, all stations using 2182 kHz were required to maintain a strictly enforced three-minute silence and listening period twice each hour, starting at h+00ᵐ, h+30ᵐ.

As a visual aide-memoire, a typical clock in a ship's radio room would have these silence periods marked by shading the sectors from h+00ᵐ to h+03ᵐ, and from h+30ᵐ to h+33ᵐ in green.

In practice, an unqualified operator would not be prosecuted for the use of either type of transmitter in a situation that turned out to be a genuine emergency.

2182 kHz forms an essential part of the Global Maritime Distress Safety System (GMDSS).