MSC.1/Circ.1280

NIGHT-TIME LOOKOUT – PHOTOCHROMIC LENSES AND DARK ADAPTATION

(19 May 2008)

1. The Maritime Safety Committee, at its eighty-fourth session (7 to 16 May 2008), considered information submitted by the United Kingdom (MSC 84/23/2) on issues affecting night-time lookout. These issues were highlighted in a recent marine accident report and related to the time required to adapt to darkness and to the wearing of glasses with photochromic lenses.

2. In this context, the Committee recalled that section A-VIII/2, part 3-1, paragraph 19, of the STCW Code states:

"The relieving officer shall ensure that the members of the relieving watch are fully capable of performing their duties, particularly as regards their adjustment to night vision. Relieving officers shall not take over the watch until their vision is fully adjusted to the light conditions",

and agreed that a suitable period for dark adaptation was typically 10 to 15 minutes, which needed to be taken into account in determining the watchkeeping arrangements on a ship.

3. The Committee noted that on some large vessels, crew with lookout duties, alternate periods on the bridge with periods of safety checks and fire watches in other parts of the vessel, some of which will be brightly lit. On fishing vessels, the deck lights may be very bright, and crew may come off the deck to take a watch. The same period of dark adaptation will be required every time the lookout returns to the bridge. Furthermore, it was important that darkness was maintained on the bridge – making full use of blackout procedures, ensuring that radars and console lights were dimmed appropriately and avoiding contamination from residual light and surrounding uncurtained areas.

4. The Committee also noted that photochromic lenses, which darken automatically with exposure to strong light and lighten when in dark surroundings, could reduce night vision significantly, even in their most translucent state. Accordingly, the Committee agreed that they should not be worn for lookout duties at night.

5. In this context, the Committee, further noted that Guidance on