Final answer:
Sound-powered phone circuits are a key part of shipboard communication systems, with several categories for different communication needs. Data from the NBIC on ship arrivals does not offer information about these circuits.
Step-by-step explanation:
The question pertains to the sound-powered phone circuits used aboard ships. These phone circuits are a critical part of the ship's communication system, particularly for internal communication during situations where regular electric-powered systems might fail.
On a ship, there are typically several categories of sound-powered phone circuits, each designated for specific types of communications and emergencies. Information about the specific number of categories on a particular ship can be found in the ship’s technical manuals or by consulting with the ship's communication officer.
It’s important to note that the data from Tab. 15.1: Number of overseas arrivals by the nine ship types to the continental US and the percentage of those arrivals reporting discharge as reported to the NBIC for 2011-2013 (NBIC, 2014) doesn't provide insight into the number of sound-powered phone circuits.