Trident Time & Tide Clock, 10" Black Dial (Weems & Plath 440315) Gulf of Bothnia British Admiralty Nautical Chart 1776:

British Admiralty Nautical Chart  1776: Livingston Island to King George Island is a standard nautical chart

however it is possible it was simply to distinguish the flag from similar ones in the region

The constitution defines the flag: "The national flag is composed of the colours ultramarine blue and vermilion red in alternate quarters

and Longitudinal Hull Strength

2 Hague and Hague-Visby Rules

Trident Time & Tide Clock, 10" Black Dial (Weems & Plath 440315) Gulf of Bothnia British Admiralty Nautical Chart 1776:The Trident Time and Tide wall clock features bold, white, easy to read lettering on a black face. The time is marked with white hands while the rising and falling of the tide is indicated with a red hand. This large (10 inch diameter) time and tide clock is housed in a black resin case with an acrylic crystal. The tide sector averages the Atlantic lunar tide cycle. Combination quartz time & tide movement Large black dial with easy to read bold white