Talk:Charmian II (Motorboat)

Speed

The note regarding speed cites the "miles per hour" indicating statute miles per hour:

The Department of the Navy Naval History and Heritage Command Online Library of Selected Images: Civilian Ships: Charmian II (American Motor Boat). Served as USS Charmian II (SP-696) in 1917-1918 and NavSource Online: Section Patrol Craft Photo Archive: Charmian II (SP 696) give Charmian II's speed as 25 miles per hour, implying statute miles per hour, an unusual unit of measure for the speed of a watercraft. It is possible that her speed actually was 25 knots. If 25 statute miles per hour is accurate, the equivalent in knots is 21.7.

While it was not unusual in the early part of the 20th century for non sea going vessels and particularly inland or coastal small craft to have speeds given in miles per hour other references show an equivalent or higher figure than the "25" cited in the image description explicitly as knots. This vessel was built as a racing boat and one figure of "will average 28 kn (32 mph; 52 km/h) in the races she enters" is not unreasonable. The problem is in the usage of the period, mixing miles per hour and knots in the same article abot the same boat. Then there is the weird to today's eyes use of a knot as distance as in "On one of these runs, which lasted two hours and fifteen minutes, the distance covered was over 64 knots." Assuming the use of "sea mile" and "knot" in the article are descriptions of a nautical mile, and in some usage of the period that is how "knot" in terms of distance is used, we get that 28.4 kn (32.7 mph; 52.6 km/h). Since that second article notes the motorboat is likely to be the fastest in her class in the country 28 kn (32 mph; 52 km/h) is likely a reasonable speed. Palmeira (talk) 23:38, 4 November 2021 (UTC)