Sea Switch; Lamps; Strobe; Red Lamp - mcmurdo 406 EPIRB User Manual

4.3. Sea switch

It is important to realise that the only time the EPIRB is completely off is when it is fitted in
its mounting bracket or enclosure. As soon as you take it out, a magnetic switch activates and
puts the EPIRB into its „ready" state. It will not drain the battery in this state, but it will turn
on automatically if the sea switch contacts are bridged by water. The sea contacts are the two
exposed screw heads beside the rear switches.
Although you can control the EPIRB manually with the READY and ON switches, the sea
switch overrides any manual settings. For the manual switches to operate properly the EPIRB
must first be dry so that the sea switch is de-activated.
To ensure the sea switch operates properly in rough seas, it has a built-in time delay. It has
to be wet for at least 2 seconds before it will activate and it has to be dry for a least 8 seconds
before it will de-activate.

4.4. Lamps

4.4.1. Strobe

The strobe is the visual means of locating the EPIRB. When activated, the strobe flashes 23
times per minute, with a pause during the time when the EPIRB is transmitting.
The strobe is also used to indicate the result of a self test (see section 10.1.).

4.4.2. Red lamp

The red lamp is used to indicate transmissions by the EPIRB. When activated, it flashes
alternately with the strobe to indicate a good transmission on 121.5 MHz. Every 50 seconds it
illuminates for 2 seconds to indicate a good transmission on 406 MHz.
When the EPIRB is first activated the red lamp is illuminated continuously until the EPIRB
begins to transmit, when it begins to flash.
The red lamp is also used to indicate the result of a self test (see section 10.1.).

5. OPERATING PROCEDURE

An EPIRB is a piece of life saving equipment. Its sole purpose is to call for help.
It must only be used in situations of grave and imminent danger.
Misuse can involve a severe penalty.

5.1. Sinking

If you have a category 1 „float-free" enclosure (see marking on enclosure label), then if
your vessel sinks, the EPIRB will automatically release itself from its enclosure before it
reaches a depth of 4 metres. The EPIRB will float to the surface and start to operate because
its sea switch is activated.
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