Page 175 - Offshore Electrical Engineering Manual

162 CHAPTER 14 Offshore Lighting

The detailed lighting requirements are given in Chapter 4 of CAP437 and the
specification in Appendix C. These requirements must be read in conjunction with
the comprehensive facilities for the safe landing and reception of helicopters given
in full CAP437 document.

JACKET AND LEG LIGHTING
It is important that the lower parts of oil platforms and the immediate area of sea
around them are lit. This lighting is required for the following reasons:

1. In case of a ‘man overboard’ situation.
2. To aid in the manoeuvring of supply and service vessels close to the platform.
3. To aid in the detection of leaks or inadvertent spillages into the sea.

This lighting is usually provided by floodlights, located on a lower deck, prefer-
ably in a nonhazardous area, positioned so that they may be directed at the jacket
and adjacent area of sea. The floodlights should be contained in corrosion resistant
metal (stainless steel or gunmetal) or impact resistant plastic enclosures. If located in
a hazardous area, both the luminaire and its igniter/ballast unit will need to be certi-
fied for such use.

NAVIGATIONAL LIGHTING
It is a statutory requirement that every platform is equipped with navigation lights
which may operate independently for 96 h following loss of platform electrical
power. The details below are based on the Standard Marking Schedule for Offshore
Installations issued by IALA.
The light system normally consists of two main, two secondary and various
subsidiary flashing lights, an electronic controller, a battery charger and battery of
required capacity.
The main lights are operated from the normal platform supply; operate in unison
exhibiting the Morse letter ‘U’. The composition of this Morse character must con-
form to the following:

1. The duration of each dot must be equivalent to the duration of darkness between
the dots and of that between the dot and the dash.
2. The duration of the dash must be three times the duration of one dot.
3. The darkness interval between successive Morse characters must not be less
than 8 s or more than 12 s.

The lights must be arranged to give an unobstructed white light normally vis-
ible for 15 nautical miles in any direction. The lights must be mounted at a height
of normally less than 30 m (but exceptionally 35 m) above Mean High Water Spring
(MHWS) and the beam axis directed at the horizon.