A "P" boat under the U.S. Army designation system was a Patrol or rescue vessel. The Navy used a "C" for theirs. Other prefixes you will see in this database include "Q" for personnel vessels of roughly cabin cruiser size and "QS" for fast supply boats. The final prefix found here is "J", used to designate launches of many types and sizes.
There are more boat numbers listed than there were boats produced. The reason for this is that some boats originally produced for the Navy were transferred to the Army. If I have no information linking a specific Navy hull number (ex: C-***) to a specific Army number (P-***) that hull will probably listed twice. If on the other hand I did have information on a specific Navy Hull number to a specific Army hull number, then the hull will be listed once, with both numbers appearing on the same line.
Much, but not all, of the data comes from "Report of Army Small Boat Construction, 1 July 1940 to 31 May 1945" and " U.S.. Army Ships and Watercraft of World War II". Another extensively used source was "Crash Boats" by Dave Linley & Terry Holham. Two 94 ft. prototype boats were built in 1955 or 56, but the program was dropped. The 83-foot boats were Design 203, built at the beginning of the program.
* 72' boats pre-WWII boats, one each was Located at MacDill (FL), Bolling Field (DC), and Bermuda.
** 83' boats are probably a USCG design. Some USCG #s overlap rescue boat numbers. Some sources show them as 84' Boats.