46 CFR § 108.241
Visual aids
April 15, 2021
(a) Each helicopter deck must—
(1) Have a wind direction indicator located in an unobstructed area readily visible to helicopter pilots approaching the deck;
(2) Be fitted around the perimeter with yellow and blue lights in alternate order, not more than 3 meters (10 ft.) apart; and
(3) Be marked with—
(i) The unit's identification;
(ii) A continuous line 40 centimeters (16 in.) wide on the perimeter; and
(iii) Aiming circles as may be appropriate considering deck configuration, helicopter type, and operational requirements.
(b) All markings must be in a contrasting color to the surface of the deck.