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What Does SS Stand for on a Boat? – Detailed Explanation

Written by J. Harvey / Fact checked by S. Numbers

what does ss stand for on a boat

Not all that see ‘SS’ on a boat can identify its meaning correctly in just a glance. The common interpretation of these letters is ‘steam ship’, which is not entirely wrong because it was popular in the past.

So, what does SS stand for on a boat nowadays? It’s a ‘single-screw ship’ and this term arose based on the manner of propulsion. However, many people are not familiar with this definition.

On the other hand, even boaters who are not from English-speaking countries use these two ‘S’ to name their boats. They used it just for the sake of giving a name to their vessels. ‘SS’ on boats has become popular since the early 1900s. At that time, the use of this prefix was prominent on the sea.

Other Possible Confusion


There are other interpretations for SS and this might bring confusion to some. Not being wished but it can start an argument somehow if parties have different knowledge. One meaning of SS for some people is ‘sailing ship’.

You may also see ‘SS’ on ‘USS’ which equals the United States Ship. It appears on US Navy warships and additional letters or words are present for specific purposes.

Single-Screw Ship, Meaning of SS on a Vessel at the Present

What does SS mean on a ship? Let’s go back to the past to answer this question. Back in the days of sailing, SS on a ship means ‘steam ship’ as a recognition that it’s empowered by steam.

With this basis, it can be compared to another method for elaboration. At that time, the vessel can also be operated through a gas turbine unit or diesel engine. Hence, the ship is called MV which means motor vessel.

Single-screw ship or steamship work with a single or more propeller. Another term for it is ‘iron screw steam ship’. In this ship, the propellers are at the end of the shaft, which is in front of the rudder.

This shaft is directly linked to an engine or transmission. Due to this connection, the screw and blades rotate. When the propeller’s blades rotate, they compel the ship to move.

This is a great invention by an English man named Sir Francis P. Smith as it’s still being used up to these days. Numerous manufacturers produce propellers. But the best brands are Quiksilver, YOUNG PROPS, Qiclear Marine, and VIF Jason.

Summing It up

This article relays the updated answer for the question: What does SS stand for on a boat?’. You may learn about how it was recognized in the past, but you better relate to the present interpretation. Knowing other meanings can help you avoid confusion.

Furthermore, the exact meaning of SS is a single-screw ship or steamship. Whichever of the two you use, they both refer to the single screw used to attach the propeller to the vessel.

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