19BB - “Boomin Beaver”

A little tugboat as long as a Ford F-150 is the “smallest ship in the U.S. Navy.”
At just 19 feet long, the boat is actually a “Boomin Beaver” security tug. Originally built to herd logs in waterways, the Navy boat is now an all-purpose vessel that can tow small ships and deploy floating security fences, ensuring that larger submarines, destroyers, and even aircraft carriers don’t receive unwanted visitors.
Chuck's Boat and Drive in Longview, Washington built these boats for loggers, and at some point, the U.S. Navy purchased scores of them for various harbor duties.
The nickname is so widespread, sailors thought the "BB" in the Navy's official designation for the ship, "19BB" stood for Boomin Beaver. It actually stands for barrier boat. Colleen O'Rourke, a spokeswoman for Naval Sea Systems Command, explained.
This particular tug is operating out of Point Loma Sub Base in California.
They’re used opening the gate for ships to go in and out. Unlock it, unlatch it, swing it open, and close it when the ship has passed."
Indeed, Boomin Beavers can be seen in Google Maps at the USS Constitution Museum in Boston. The Beaver at Boston Harbor can also be seen in the photo, where it's described as “operating the floating barrier” that surrounds the oldest commissioned ship in the Navy. The ships are also visible at several naval bases across the U.S., including Naval Base Kitsap Bangor, and Naval Base San Diego.
All of the Boomin Beavers are located near floating security nets, identified in the imagery as lines of connected buoys. The nets provide a visible security cordon, a “do not cross” line that keeps local shipping away from billion dollar warships. You can catch similar tugs at Norfolk Naval Station and Kings Bay, Georgia.
One of the tiny boats was put up for government auction in 2006. The listing described the boat as 19 feet long and 10 feet wide, with a draft of 5 feet. The power plant is listed as a Cummins 6BTA5.9 diesel engine rated at 260 hp with ZF marine transmission. The highest bid for the boat was $100,025, which seems like ... a lot for a boat this small.
But then again, nothing is cheap when it comes to Navy ships.