Ship Hull Classifications-The Rest of the Armed and Uniformed Forces

The services use hull classification symbols (sometimes called hull codes or hull numbers) to identify their ship types and each individual ship within each type. 

This article will cover the United States Coast GuardNational Oceanic and Atmospheric Administration (NOAA), United States Army and United States Air Force.

United States Coast Guard Hull Classifications

US Coast Guard

From 1942 until 1965, the Coast Guard used USN hull classifications, but with a leading character of "W" to indicate it was a Coast Guard craft.  [historical classifications on ships belonging to Revenue Marine and the Revenue Cutter Service (predecessor to the United States Coast Guard) may be found at

Why a “W”?  Well, according to the Coast Guard historians – no one really knows, but they have several theories:

Theory:  "W" was used during the 1930s as the routing symbol on Treasury Department correspondence to designate the Coast Guard.

Theory:  it stands for "weather patrol," one of the major tasks assigned to the Coast Guard.

Theory:  by international agreement regarding radio communications the United States was able to use the letters "A", "K", "N" or "W" and since "W" was unused at that time, it was chosen to designate a Coast Guard cutter.

Theory:  one officer noted that "W" was chosen since it was unused and was also the first letter of the last name of the officer who attended the meeting when the designation was chosen.

Theory:  "W" was an unused letter on the Navy's designation alphabet and was arbitrarily assigned to designate a Coast Guard cutter.

Regardless, the practice stuck and each cutter still bears the "W."

In 1965, the Coast Guard retired some of the less mission-appropriate Navy-based classifications and developed new ones of its own.

Currently, the Coast Guard has the following cutter (any CG vessel 65 feet in length or greater is called a cutter) hull classes:

Icebreaker - designated WAGB

National Security Cutter - designated WMSL

High Endurance Cutter - designated WHEC

Training Barque Eagle - designated WIX

Medium Endurance Cutter - designated WMEC

Seagoing Buoy Tender / Icebreaker - designated WLBB

Seagoing Buoy Tender - designated WLB

Coastal Buoy Tender - designated WLM

Inland Construction Tender - designated WLIC

Fast Response Cutter - designated WPC

Icebreaking Tug - designated WTGB

Patrol Boat - designated WPB

Inland Buoy Tender - designated WLI

River Buoy Tender - designated WLR

Small Harbor Tug - designated WYTL

Additionally, the Coast Guard classifies its boats (any CG vessel less than 65 feet in length) as:

Arctic Survey Boat - designated ASB

Motor Life Boat - designated MLB

Utility Boat – designated UTB

Response Boat - Small – designated RB-S

Response Boat - Medium - designated RB-M [in development]

Response Boat - Homeland Security – designated RB-HS

Law Enforcement Special Purpose Craft - designated SPC-LE

Long Range Interceptor - designated LRI [in development]

Transportable Port Security Boat - designated TPSB

There are a couple of boats that I have not discovered hull designations for, those being the Aids to Navigation Boats and Special Purpose Craft Airboats.

National Oceanic and Atmospheric Administration Hull Classifications


The National Oceanic and Atmospheric Administration (NOAA) is one of the United States uniformed services, but falling under the United States Department of Commerce.  In 1970, the NOAA took over the former Coast and Geodetic Survey fleet as well as research vessels of other government agencies, and after doing so developed a hull classification symbol system for its fleet.

The NOAA fleet is divided into two broad categories:

Research Ships – these are oceanographic and fisheries research vessels, which are given hull numbers beginning with "R"

Survey Ships – these are generally hydrographic survey vessels and receive hull numbers beginning with "S".

The category letter is followed by a three-digit number, separated by a space.  The first digit indicates the NOAA "class" (i.e., size) of the vessel, which NOAA assigns based on the ship's gross tonnage and horsepower, while the next two digits combine with the first digit to create a unique three-digit identifying number for the ship.  For example, pictured above is NOAAS Pisces (R 226). 

Unlike the Navy and Coast Guard systems, once an older NOAA ship leaves service, a newer one can be given the same hull number – as an example, "S 222" was assigned to NOAAS Mount Mitchell (S 222), then was later assigned to NOAAS Thomas Jefferson (S 222), which entered NOAA service after Mount Mitchell was stricken.

United States Air Force Hull Classifications

Currently, the United States Air Force operates a small fleet of drone recovery vessels nicknamed the "Tyndall Navy" (because you see, they are based out of Tyndall Air Force Base), consisting of three 120-foot drone recovery vessels and two smaller vessels.  These ships are for recovering pieces of wreckage from drones and aerial targets from the waters of the Gulf of Mexico and support range safety, patrol, and salvage operations. 

As well, the Rising Star is noted as being the Air Force's only tugboat, operating out of Thule, Greenland.

Wow, that was really short.  Okay, so let’s go back in time a little…

Back in 1957, the Air Force began operating a small fleet of Missile Range Instrumentation Ships to support missile test ranges [Air Force Fact Sheet: Development of the 45SW Eastern Range].  The Air Force designated their ships as "ORV" for Ocean Range Vessel, with 5 types of Missile Range Instrumentation Ships (as well as a tugboat).

The Air Force had five “types” of ORV:

FS Type – converted merchant vessel.

C1-M-AV-1 Type - C1 types were the smallest of the 3 original types designed by the United States Maritime Commission, and C1-M-AV1 was designed for short coastal runs.

VC2-S-AP3 Type- Victory-class Merchant Vessel

C4-S-A1 Type – C4's were the largest cargo ships built by the Maritime Commission during World War II.  The C4-S-A1 were designed as Troop Transports.

EC2-S-C1 Type – Liberty class Merchant Vessel.

The smaller FS types were retired by 1960.  A few years later, the US Navy took over operation of the larger C1-M-AV-1 type, and re-designated them under the USN system as AGM.  By 1969, the original larger ORV were out of service.



United States Army Hull Classifications

The Army currently has five types (not counting U.S. Army Corps of Engineers ships) of vessels:

Landing Craft Utility, designated as LCU

Large Tug, designated as LT

Logistics Support Vessels, designated as LSV

Theater Support Vessel, designated as TSV

USAV Worthy is a T-AGOS class ship (auxiliary general ocean surveillance ship) being used as Kwajalein Mobile Range Safety System (formerly a USNS craft).

And, because they were mentioned, the U.S. Army Corps of Engineers has a total of 11 Dredge Vessels, divided into hopperand non-hopper dredges.