§ 83.31 § 83.31 Seaplanes (Rule 31). Where it is impracticable for a seaplane or a WIG craft to exhibit lights and shapes of the characteristics or in the positions prescribed in the Rules of this subpart, she shall exhibit lights and shapes as closely similar in characteristics and position as is possible.
33 CFR §83.31
33 CFR Part 83
TL;DR
Where it is impracticable for a seaplane or a WIG craft to exhibit lights and shapes of the characteristics or in the positions prescribed in the Rules of this subpart, she shall exhibit lights and shapes as closely similar in characteristics and position as is possible.