Stories and Battle Histories of the IJN's Patrol Boats

23 December 2019

By Bob Hackett, Sander Kingsepp and Peter Cundall

Discussion & Questions

(Rerated MOMI-class DD as a Patrol Boat by Takeshi Yuki)

Just prior to the Pacific War, a number of former IJN destroyers were replaced by newer classes as first-line combatants. The older destroyers were reclassified as patrol boats. All such vessels were then modified to varying degrees. Most had one or more boilers removed which reduced their speed. All had their torpedo tubes and at least one of their 4.7-inch/45 cal main guns removed. Extra ballast was added to compensate for the loss of topside weight and to increase stability. Some vessels were fitted to carry and launch up to two 46-ft Daihatsu landing craft. The interior spaces of some vessels were modified to accommodate from 150 to 250 troops. 25mm AA guns and depth charge racks and throwers were fitted. The changes increased their displacement by over 900-tons. This page will cover the activities of 12 such vessels that were in service as patrol boats.

Tabular Records of Movement (TROMs):

IJN Destroyers Rerated as Patrol Boats

(DD classes link to specification summaries)

Ex-Minekaze Class

PB-1 (revised 5/25/2018)
PB-2 (revised 11/15/2018)

Ex-Momi Class

PB-31(revised 10/19/2018)
PB-32(posted 3/28/2008)
PB-33(revised 2/1/2015)
PB-34(revised 5/25/2018)
PB-35(revised 11/1/2016)
PB-36(revised 11/15/2018)
PB-37(revised 11/6/2016)
PB-38(revised 5/25/2018)
PB-39(revised 11/15/2018)

Ex-Wakatake Class

PB-46 (revised 11/11/2017)

During the war, a number of former American, British and Dutch vessels that had been scuttled in various captured ports in the Far East were raised and repaired by the Japanese. This page will also cover the activities of nine such ex-Allied vessels that were later in the service of the Imperial Navy as patrol boats.

Ex-Foreign Vessels in IJN Service as Patrol Boats

(Ex-Countries link to specifications summaries)

Ex-British Vessels

PB-101 (revised 2/8/2015)

Ex-American Vessels

PB-102(revised 11/15/2015)
PB-103(revised 5/22/2016)
PB-105(revised 12/23/2019)
PB-107(revised 11/27/2010)

Ex-Dutch Vessels

PB-104 (revised 11/15/2015)
PB-106 (revised 5/15/2010)
PB-108 (revised 11/27/2010)
PB-109 (revised 5/15/2010)

As with other small combatants, data for some vessels are incomplete for some time periods. Readers with access to missing data are requested to post the information on the Discussion & Questions board or the IJN Ship Message Board.

Bibliography of Sources

About the Authors

Mr. Robert Hackett is a military historian and researcher. Retired from the United States Air Force and later from the aerospace industry, he resides in Florida.

Mr. Sander Kingsepp, a native of Estonia, is also a military historian and researcher. A talented linguist, Sander's translations of Japanese source materials have greatly enhanced these TROMs.

Mr. Peter Cundall is a maritime historian and researcher who specializes in merchant ships. He resides in Australia and works in the maritime industry.

Questions to the authors concerning these TROMs should be posted on the Discussion and Questions board.