Ship Prefixes: Understanding SS and Other Common Uses

When it comes down to boat names, it's not all that uncommon to come across a vessel with letters before its name. Though these can seem random at first glance, each of these prefixes actually has a specific meaning attached to it. They serve as an additional indicator of what the purpose of a vessel is for easy identification.

In these cases, the boat's full name likely has the extended version of its purpose in its title, but the abbreviated prefixes often end up on the hull for convenience. These abbreviations also see use in everyday speech as well. In some cases, a prefix or designation may apply to a boat, but it doesn't see a use for that ship's name at all.

The SS designation is one such prefix, and it has a meaning and history that may not be what you expect. We'll explore this and other typical ship prefixes below!

Common Ship Prefixes

Between military and commercial vessels, ship prefixes serve the use of indicating the purpose of a boat. While not all countries use the same naming conventions, US and UK ships often use many of these prefixes to determine their origins. Many others have come into naval use. Some ship prefixes you may encounter are:

  • Cable Ship – CS
  • Fishing Vessel – FV
  • Gas Turbine Ship – GTS
  •  Lifeboat – LB
  • Motor Tanker – MT
  • Motor Vessel/Motor Ship – MV/MS
  • Motor Yacht – MY
  • Nuclear Ship – NS
  • Platform Supply Vessel – PSV
  • Research Vessel – RV
  • Royal Mail Ship – RMS
  • Sailing Vessel – SV
  • Training Ship – TS

As with many other ship prefixes in use, most of their meanings begin to seem obvious and straightforward once you start to learn the types of boats that can have them. Many Navies have their structure of additional ship prefixes to further designate the vessel's use within the larger hierarchy. As ships have changed over the years, some designations have even fallen out of use.

While military and government vessels will almost always contain a prefix in their name, these indicators aren't as strictly used in commercial and privately owned boats. Some ships choose to omit a prefix altogether.

So What Does SS Mean on a Boat?

While many of these prefixes can seem obvious, SS is a little bit trickier because many options can come to mind at first glance. It can be straightforward to guess that the SS stands for "steamship;" though this was once true, it is not always the case in modern usage.

While some prefixes help to determine the purpose of the vessel, others saw historical use as an indicator of the power source for the boat. SS often stood for "steamship," as steam what made these vessels operate. It was also a clear indicator that a boat differed from the slower performing means of propulsion, such as sailing and rowing power.

In more specific designations, SS has also come to mean a "single-screw ship," which sometimes persists into modern usage. The single screw refers to the method of propulsion. However, this terminology is less well known, as "steamship" often prevails as the meaning of SS when used as a boat name prefix.

SS is also one of the prefixes commonly recognized across waters, even those where English isn't the universal language. However, as the technology has changed, SS does not see as much use as it did in the early 1900s, where these vessels were much more prominent on the waters.

Similar and Potentially Confused Prefixes

As mentioned, some other interpretations are possible. The SS is also like some different prefixes, which contain identical letters. Some examples include:

"Sailing Ship." As sailing is another propulsion method for boats, it can be easy to misinterpret SS as standing for "sailing ship." As we've already discussed, this meaning is not the case. The correct prefix for these types of boats is SV, which stands for "Sailing Vessel."

USS. While containing some of the same letters, the USS ship prefix holds its meaning: "United States Ship." This prefix sees use on United States military vessels, particularly those in the Navy. Following modern military naming conventions, all warships beat "USS" as a prefix, while supporting Navy vessels have names that indicate their specific purpose. "USNS" (United States Navy Ship) sees use to identify such boats.

Other Boat Naming Conventions

Aside from prefixes indicating the type of vessel, boat names often follow specific conventions, which can depend on the country of origin. Often, boats will carry names of women—common British practice of the past was to use names specifically ending in "-ia" for ships.

Regardless of the origin of a name, it will always be in italics when written out (i.e., the Titanic). This formatting includes any prefixes connected to the title.

It is acceptable to write out prefixes with periods between each letter (S.S.) or without (SS), though you should remain consistent throughout a body of work. Sometimes, names are also written with slashes to separate the letters (S/S).

Merchant Vessels and Research Vessels

Though we've touched on these prefixes earlier, we're about to go into merchant and research vessels in more depth.

Merchant Vessels (MV)

A merchant vessel (MV) is a ship that operates under commercial means. These boats are often responsible for transporting goods or people, and they require payment to do so. Sometimes, the term is interchangeable with a trading vessel (TV), as a means of working for hire are the same. It is this payment system that also distinguishes them from other boats that may transport the goods or people for other purposes. In American usage, the term "commercial vessel" also applies to these boats.

For example, while a cruise ship transports people that have paid for its serves, the main focus of these boats is to provide entertainment and relaxation. This distinction makes cruise ships fall under the broader category of pleasure craft, which can also include smaller, personal watercraft with outboard motors. These boats do not always include a prefix in their name, but they can to further indicate their purpose.

Military vessels can also transport people and goods, but they are not available for hire. Instead, these ships operate under military purposes. However, merchant vessels can see use as extra support to the military in times of need, if their specifications meet the set requirements.

Research Vessels (RV)

A research vessel (RV) is a ship dedicated to the purpose of conducting research. Depending on the setup of these boats, they can handle multiple purposes. However, it is much more common for these vessels to serve one specific purpose, as it allows for specialization of equipment and ship build from power boat manufacturers. Some uses for research vessels include:

  • Fisheries – These have a focus on studying fish themselves and, as such, house fish-finding equipment, nets, water sample collectors, and lab space. It is the latter factor that distinguishes them to dedicated fishing vessels.
  • Naval – A naval research vessel will have the means to detect mines, submarines, and weapon trailing.
  • Oceanographic – These boats study waters, the biospheres within them, their climates, and any other number of matters related to ocean study. They often have underwater vehicles on board to help further explore areas.
  • Oil – Oil exploration boats have the equipment to drill into the seabed and determine if any oil is available in a set location.
  • Polar – These ships have builds specifically meant to navigate icy waters safely, as well as the equipment to study such environments. Because they can travel through ice fields, they often serve as supply ships for Antarctic research facilities.

While a boat may be fitting of the SS prefix, it is more likely to receive a different one if it has a much more specific purpose or fits into a larger group, such as a navy.