Steamship Designations / Prefixes (Merchant Vessels), 1880s–1960s
The SS George Washington, Repaired at the Todd Shipyards Corporation. Shipping Magazine, 10 September 1921. | GGA Image ID # 1d41b2fa6d
Prefixes are short codes placed before a ship’s name to indicate propulsion, role, or special status. In the late 19th and early–mid 20th centuries they were common in timetables, passenger lists, and press reports—but not always used consistently. Understanding them helps researchers interpret lists correctly and avoid false assumptions about a vessel.
Why prefixes vary
House style: Lines and newspapers followed their own style guides (periods/slashes optional).
Technology shifts: As fleets modernized (steam → motor → turbo-electric), prefixes evolved.
Contract status: Some designations (e.g., RMS) reflect a mail contract, not machinery.
Document purpose: A souvenir passenger list might say SS, a postal notice RMS, the technical registry TSS—for the very same ship.
Quick Reference (Merchant & Liner Usage)
Tip: Italicize ship names (e.g., SS United States) but not the prefix itself.
Prefix: SS / S.S.
- Meaning / Expansion: Steamship (steam-powered)
- Typical Era: ca. 1840s–1960s
- What It Tells You / Notes: The workhorse designation. Used broadly for steam-propelled cargo-passenger liners. Default when no special status is highlighted.
Prefix: RMS / R.M.S.
- Meaning / Expansion: Royal Mail Ship
- Typical Era: 1840s–present (UK contract)
- What It Tells You / Notes: Indicates a UK GPO mail contract. It’s about carrying Royal Mail, not engine type. Many famous liners were RMS throughout their mail-contract period.
Prefix: RMMV / R.M.M.V.
- Meaning / Expansion: Royal Mail Motor Vessel
- Typical Era: 1920s–1960s
- What It Tells You / Notes: Motor (diesel) vessel with Royal Mail contract (e.g., RMMV Britannic).
Prefix: MV / M/V
- Meaning / Expansion: Motor Vessel
- Typical Era: 1920s–present
- What It Tells You / Notes: Diesel (or diesel-electric) propulsion. Common on cargo-passenger ships and later liners.
Prefix: MS / M/S
- Meaning / Expansion: Motor Ship
- Typical Era: 1920s–present
- What It Tells You / Notes: Same idea as MV; some lines preferred MS.
Prefix: TSS
- Meaning / Expansion: Twin-Screw Steamer (also found as Turbine Steam Ship in some sources)
- Typical Era: 1890s–1960s
- What It Tells You / Notes: Steamship with two propellers (or turbine-driven). Period usage varies; check line practice.
Prefix: TS
- Meaning / Expansion: Turbine Steamer
- Typical Era: 1900s–1960s
- What It Tells You / Notes: Emphasizes steam turbines rather than simple reciprocating engines.
Prefix: PS
- Meaning / Expansion: Paddle Steamer
- Typical Era: 19th c.–mid-20th c.
- What It Tells You / Notes: Paddle-wheel propulsion, common on short-sea and excursion services.
Prefix: TEV
- Meaning / Expansion: Turbo-Electric Vessel
- Typical Era: 1920s–1960s
- What It Tells You / Notes: Steam turbines driving generators, which power electric motors on the shafts.
Prefix: GTS
- Meaning / Expansion: Gas Turbine Ship
- Typical Era: Post-WWII–1970s
- What It Tells You / Notes: Gas-turbine propulsion (rarer on liners, appears later).
Prefix: LB
- Meaning / Expansion: Lifeboat
- Typical Era: Always
- What It Tells You / Notes: Designation for the craft itself (e.g., LB 12), not a passenger ship prefix.
Prefix: T/S
- Meaning / Expansion: Training Ship
- Typical Era: Various
- What It Tells You / Notes: Merchant or naval training role; occasionally appears in passenger-carrying contexts (cadets).
Worked examples
- RMS Mauretania (Cunard): steam turbine express liner with a Royal Mail contract—hence RMS, not SS, in most publicity and lists.
- RMMV Britannic (White Star): diesel-powered and contracted to carry Royal Mail.
- TSS Cameronia (Anchor Line): twin-screw steamer (some sources cite “turbine”).
- MV / MS Georgic (White Star): motor vessel terminology varied by source.
Common misconceptions (and quick fixes)
“RMS = every UK liner” ❌ → Only those under a Royal Mail contract. A ship could be SS on one line’s artwork and RMS in postal or official notices if a contract applied.
“RMS means ‘Royal Merchant Ship’” ❌ → It’s Royal Mail Ship.
“TSS always = turbine” ❌ → Often “Twin-Screw Steamer”; some lines used it for turbine steamers. Context matters.
“Prefixes change every voyage” ⚠️ → Mail designations relate to contracts. A ship commonly retained RMS throughout the contract period, even though individual sailings emphasized or omitted it in print.
Usage tips for writers & editors ✍️
- Be consistent within a page. Pick SS or S.S. and stick with it.
- Don’t stack mutually exclusive prefixes. Use RMS or SS, not RMS SS.
- Respect house style in quotes/images. Transcribe what’s on the artifact; normalize elsewhere.
- Cite both forms when helpful for search. First mention: “SS (S.S.) and MS (M/S) are used interchangeably in period sources.”
- Ship names in italics; prefixes roman. Example: RMS Aquitania.
Why this matters for research 📚
Genealogists & family historians: Prefixes explain why the same ship appears under different labels in newspapers vs. passenger lists. Use variants when searching manifests and press mentions.
Teachers & students: Prefixes offer a quick window into technology (steam vs. diesel) and services (mail contracts), perfect for primary-source analysis.
Historians & maritime enthusiasts: Accurate prefixes help date photographs, ads, and timetables, and untangle line-specific branding.
“See also” (Related Topics)
📚 Teacher & Student Resource
Many of our FAQ pages include essay prompts, classroom activities, and research guidance to help teachers and students use GG Archives materials in migration and maritime history studies. Whether you’re writing a paper, leading a class discussion, or tracing family history, these resources are designed to connect individual stories to the bigger picture of ocean travel (1880–1960).
✨ Educators: Feel free to adapt these prompts for assignments and lesson plans. ✨ Students: Use GG Archives as a primary source hub for essays, genealogy projects, and historical research.
📘 About the Passenger List FAQ Series (1880s–1960s)
This FAQ is part of a series exploring ocean travel, class distinctions, and the purpose of passenger lists between the 1880s and 1960s. These resources help teachers, students, genealogists, historians, and maritime enthusiasts place passenger lists into historical context.
- Why First & Second Class lists were produced as souvenirs.
- How class designations like Saloon, Tourist Third Cabin, and Steerage evolved.
- The difference between souvenir passenger lists and immigration manifests.
- How photographs, menus, and advertisements complement list research.
👉 Explore the full FAQ series to deepen your understanding of migration, tourism, and ocean liner culture. ⚓
📜 Research note: Some names and captions were typed from originals and may reflect period spellings or minor typographical variations. When searching, try alternate spellings and cross-check with related records. ⚓
Curator’s Note
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