Final answer:
The provided text does not specify the color of the cranes on Seattle's waterfront, though industrial cranes are often painted in high visibility colors like yellow or red.
Step-by-step explanation:
The color of the huge cranes that stood guard along the waterfront of the Seattle shoreline is not explicitly mentioned in the given text extracts. These various excerpts, with descriptions of maritime activity and the coastal environment, do not specify crane colors but do evoke a sense of place and time via visual imagery of sea-related scenes.
The extracts mention elements such as the white sails of schooners, the gray walls of granite storehouses, and the changing colors of the sea and sky. However, without direct reference to the cranes in question, we are unable to determine their color from the provided text.
In the historical context and considering typical crane colors, it's possible that the cranes might have been painted in high visibility colors such as yellow or red to ensure they are easily seen by maritime and dock workers. Often, large industrial equipment is painted in such colors for safety and visibility purposes. To get a definitive answer on the color of Seattle's waterfront cranes during a specific time period, one would likely need to consult historical photographs or records from that era.