Board Thread:Event Community Discussion/@comment-28069733-20170521154728/@comment-1637496-20170529061337

Vcharng wrote: This document is weird, a torpedo boat in the USN is PT, not TB.

I didn't find Patrol boat being PB as well. PT is motor torpedo boats,  it's listed in the "special service" (auxiliaries) section of that page. TB was used for the original, steel hulled and steam driven, torpedo boats;  article 8 of the London Treaty resurrected the type in the Japanese (Chidori class), French (La Melpomène class) and Italian (Spica class) navies, basically only the United States and British navies passed on building these mini-destroyers.

PB is listed in the DANFS.