Military Sealift Command - Mariner Class Conversions

An Introduction by Terry Holtham

Front to Back - Cape Avinof, Cape Bover, Cape Juby, Cape Gibson, Gem State

For those who collect post war / modern US Navy models both Tri-ang and other manufacturers produce a wide range of carriers, cruisers, destroyers, frigates, and submarines etc - what’s missing, however, are models of the US fleet auxiliaries /support ships and the sea-lift vessels operated by MSC (Military Sealift Command).

Argos and Mountford produce a few examples of these ships, which are still available, and Trident made models of a number of the older now out of commission “auxiliary” ships but they are no longer in business and their models are difficult to obtain..

Happily all is not lost, in the course of my initial research I discovered a lovely break bulk ship (Cape Gibson) that was listed as being held in the US reserve fleet and furthermore that she was a “Mariner” type ship so knowing that Tri-ang made a series of Mariner models I checked them out and decided, that with a bit of imagination and some artistic licence, they would be a suitable basis for conversion.

Although there is nothing wrong with the funnels fitted on the later four models, I noted that the shape of the funnels on the earlier pair (the APL and Matson models) were closer to those in the photograph of Cape Gibson and accordingly ordered a Matson Lines model to start with.

While I was waiting for the model to arrive I decided, as an experiment, to strip down a pair of Tri-ang’s modern US Navy models, namely an Arleigh Burke and an Oliver Hazard Perry, to see how they looked “bare” and whether a repainting of same would turn out OK.

I am delighted to report that the original paint came off with little effort and I had no trouble repainting them with Humbrol paints –further photographs and a brief write up are available here.


Obviously a bit of research is required for any conversion and as I went along I discovered quite a lot of information about the C4 “Mariner” class ships as well as a number of ships that were built to modified designs.

The C4-S-1a "Mariner" class were the first ships built under the auspices of the US Department of Commerce Maritime Administration (US MARAD) after they took over from the wartime US Maritime Commission in 1950. The impetus for their construction was the Korean War (1950 - 1953) which reinforced the crucial role of sea transport in US military operations while at the same time revealing the limitations of the World War II Victory ships that were activated from America's reserve fleets.

A total of thirty five (35) ships were built to the original C4-S-1a design all of which were given names ending in "Mariner", thus giving rise to the class name. The first ships were delivered in 1952 and a total of twenty three (23) of the "Mariners" saw service in the Korean War.

The C4-S-1a was designed as "a ship of the future", fitted out with technological advancements such as engine room automation and hydraulically operated hatch covers which reduced the manpower requirement, and were the largest freighters in service when built. They were capable of speeds in excess of 20 knots and were fitted with "National Defence" features that provided extra horsepower for military operations which commercial operators were not allowed to use - the extra nozzle blocks on the turbines were locked with chain and sealed with hefty "fines" imposed on the operator if the seals were found to have been broken.

In the mid 1950's, after being laid up at the end of the Korean War when American shipping companies showed no interest in purchasing them, MARAD made the ships available under an "operating leasing" arrangement which as far as I can ascertain was taken up by no less than 24 shipping companies.

These included such well-known names as American President Lines (APL), Matson Navigation Co, Lykes Bros Steamship Co, United States Lines, American Mail Lines, Pacific Far East Line, Moore McCormack Inc and States Line - as well as a number of lesser known companies such as Pope & Talbot Inc, Mississippi Shipping Co, A H Bull & Co, and Isthmian SS Co - so for the merchant ship enthusiast there are potentially 24 different liveries that can be made from the basic Tri-ang model.

Within a few years many of the ships were purchased from MARAD by the major American shipping lines and, unfortunately, I have had little success locating photographs of the ships in the liveries of some of the less well known companies.

"Howell Lykes" (C4-S-66a) - Lykes Bros Steamship Co

"Mormacsaga" (C4-S-1u) Moore McCormack Lines

(I should note at this point that while the Tri-ang Volunteer Mariner and President Buchanan models with their metal funnels are a very good likeness to the original 35 ships, and lovely models at a very reasonable price, they are missing the foredeck cargo hatch - an error that is easily made good with a piece of 0.5mm thick plasticard. In my opinion the lifeboats also look a bit tiny and the plastic masts / derricks are a bit “chunky” but these are easily replaced with bits from the spares box or fabricated from plasticard and brass wire if you are so inclined.)

Three of the original ships were subsequently converted to passenger ships - Free State Mariner and Pine Tree Mariner were purchased by Matson Lines in 1956 and converted into the (almost) sister ships SS MONTEREY and SS MARIPOSA respectively while Badger Mariner was purchased by American Banner Lines in 1957 and converted into the SS Atlantic later purchased by Orient Overseas Lines as SS Universe Campus - so if you are feeling really ambitious these are further possibilities for conversion.

SS Monterey (ex Free State Mariner) of Matson Lines

The US Navy also took up five of the original ships and one of the derivative designs for various purposes -

USS Paul Revere (APA-248)

With the advent of containerisation most of the ships were re-configured to carry containers, at least as deck cargo, and some were extensively modified including in some cases lengthening by approximately 100 feet.

American Alliance (ex Show Me Mariner) of United States Lines after lengthening by 100 feet

Derivate Designs / Sub-types:

After researching the original 35 Mariners I investigated the various sub-types / derivatives listed on the "US Maritime Commission" website (created by an enthusiast in Germany), which has technical specifications and excellent profile drawings for most of the ships, and from Tim Colton’s “Shipbuilding History” website I obtained a list of all the break-bulk cargo ships built by the US since World War II including the number of each type built and a list of all the ships names.

As far as I can determine a further ninety (90) ships were built to seventeen (17) derivatives of the original C4-S-1a design. There are visible differences between the various sub-types - such as shorter or longer foredecks; different types of cargo handling equipment; superstructures located further aft; as well as many variations of funnel - and some of the derivative designs are so substantially different to the original layout that I don't think a conversion would be practical although fortunately, at least from my perspective, none of these groups of ships ended up in military service.

A full list of all the original C4-S-1a Mariner Class ships and derivative designs together with brief histories is available on this page.

Many of the Mariner type ships were "traded in" to MARAD in the late 1970's under a program introduced by the US Government (HR 7278) to replace obsolete vessels and build up the National Defense Reserve Fleet (NDRF) in response to the rapid decline in the size of the US flagged break bulk "tramp" fleet (as a result of containerisation) which America had historically been able to call on in times of national emergency.

With the aid of the "Unofficial US Navy Site" (created by another German enthusiast), and some nuggets I discovered on the MARAD website, I have identified eleven "types" totalling 45 individual ships that were "traded in" to MARAD of which 26 ships of eight different "types" have seen service with Military Sealift Command.

For ease of reference I have listed the ships below -

Design Ships MSC "Class" Ships Designation Notes
C4-S-58a African Mercury
African Meteor
African Neptune
African Comet
African Sun

African Dawn
Cape 'A' Class Cape Ann #
Cape Alexander *
Cape Archway #
Cape Alva
Cape Avinof #

T-AK 5009
T-AK 5010
T-AK 5011
T-AK 5012
T-AK 5013

Cape 'A' Class spares
C4-S-66a Dolly Turman
Frederick Lykes
Howell Lykes
Velma Lykes
Mason Lykes
Cape 'B' Class Cape Breton
Cape Bover
Cape Borda
Cape Bon
Cape Blanco
T-AK 5056
T-AK 5057
T-AK 5058
T-AK 5059
T-AK 5060
C5-S-75a Alaskan Mail
Indian Mail

Korean Mail
Cape 'G' Class Cape Girardeau *#
Cape Gibson *#

(Cape Greig)
T-AK 2039
T-AK 5051


Not taken up
C4-S-1u C E Dant
M M Dant


Cape 'J' Class Cape John *#
Cape Jacob *#
Cape Johnson *#
Cape Juby *#


T-AK 5022
T-AK 5029
T-AK 5075
T-AK 5077

TS Empire State VI

Cape 'J' Class spares
American Commander
American Contractor
American Crusader
Pioneer Commander
Pioneer Contractor
Pioneer Crusader
T-AK 2016
T-AK 2018
T-AK 2019
President Harrison
President Monroe
President Polk
Crane Ship
Keystone State
Gem State
Grand Canyon State
Japan Mail
Washington Mail

Philippine Mail
Crane Ship

Not converted
Diamond State
Equality State


(T-ACS 11)

Held for spares

Crane Ship

Not converted
Green Mountain State
Beaver State

Allison Lykes
Mallory Lykes
T-ACS 10


Never activated
President Lincoln
President Tyler
Never activated
American Racer
American Ranger
American Reliance
American Resolute
American Rover
American Racer
American Ranger
American Reliance
Never activated
Santa Barbara
Santa Clara
Santa Elena
Santa Lucia
Santa Clara
Santa Elena
Santa Lucia
Never activated

In the early 1990's all of the Cape 'A', Cape 'G' and Cape 'J' Class ships were modified under the Merchant Ship Naval Augmentation Program (MSNAP) to enable them to supplement the US Navy’s support ships by providing limited underway replenishment (UNREP) services.

Under this program seven ships, marked with an "*" above, were fitted with the Modular Cargo Delivery System (MCDS) allowing them to provide connected replenishment (CONREP) services to any US Navy ship equipped with an appropriate receiving station using the US Navy’s Standard Tensioned Replenishment Alongside Method (STREAM) system, and nine ships, marked with a "#" above, were fitted with “hover only” flight decks allowing them to provide limited vertical replenishment (VERTREP) services utilising the receiving ships' helicopters.

The main purpose of the reserve fleet is to provide additional cargo carrying capacity in times of national emergency and all of the ships that were activated for service have been operated by Military Sealift Command in their original configurations at some point in time, other than being painted grey, so a simple re-paint of the Mariner class model will produce a pleasing enough military looking ship to add to your fleet.


Although one needs a bit of imagination and a certain degree of artistic (modelling) licence I concluded that with varying degrees of effort it would be possible to create the following conversions from the basic Tri-ang "Mariner" model -

  1. Attack Cargo ship - USS Tulare (AKA 112)
  2. Attack Transport - USS Paul Revere (APA 248) / USS Francis Marion (APA 249)
  3. Ballistic Missile Test ship - USS Compass Island (AG 153) / USS Observation Island (AG 154)
  4. Missile Range Instrumentation ship - USNS Observation Island (T-AGM 23)
  5. Oceanographic Research ship - USNS H H Hess (T-AGS 38)
  6. Keystone State Class Crane Ship
  7. Cape 'A' Class break bulk cargo ship (with or without MCDS / VERTREP modifications)
  8. Cape 'B' Class break bulk cargo ship
  9. Cape 'G' Class break bulk cargo ship (with or without MCDS / VERTREP modifications)
  10. Cape 'J' Class break bulk cargo ship (with or without MCDS / VERTREP modifications)
  11. T-AK 2016 "Pioneer" Class break bulk cargo ship

As I have models of USS Tulare (Trident No. T138) and USS Paul Revere (Trident No. T158) these were not the subject of my conversions - I have concentrated on the auxiliary vessels. My aim was to produce some military looking break bulk cargo ship models and, while not totally accurate in all respects, I am happy with the results.

Further information can be obtained from the following links -
MARAD Web Site Brief history of the Maritime Administration (MARAD)
MARAD Web Site Monthly Inventory archives of ships held in the RRF / NDRF
US Merchant Marine Web Site MSTS Service in the Korean War
Global Security Web Site C4-S-1a Mariner (APA-248 Paul Revere / AKA-112 Tulare)
US Maritime Commission Web Site (Germany) Profile drawings and technical specifications of the "standard" ship types built by the US Maritime Administration and its forebears
"Unofficial US Navy Site (Germany) US Military Sealift Command ship classes and ships
Tim Colton’s “Shipbuilding History” Web Site List of break bulk ships built in US shipyards since World War II

The Naval Institute Guide To The Ships And Aircraft Of The U.S. Fleet by Norman Polmar
The Naval Institute Guide to Combat Fleets of the World by Eric Wertheim

Details of my other conversions can be accessed from the "Resources" menu - "Upgrades & Conversions" sub-menu OR from the links below.

Introduction Cape 'A' Class Cape 'B' Class Cape 'G' Class Cape 'J' Class Crane Ship