Ship vs. Boat — What’s the Difference?

If you’re confused about the difference between a ship and a boat, know that you are not alone. As we will highlight throughout this guide, even the US Navy can’t seem to come up with a universal definition.

This confusion didn’t always exist. In the age of sail, a ship was defined as a square-rigged vessel with at least three masts. During that period, even your average landlubber could tell at a glance whether a particular craft was a boat or a ship.

But nowadays, there’s no such simple distinction. Instead, we’re left with some overlapping definitions, not all of which make sense. In light of this confusion, let’s take a closer look at the differences between a boat and a ship.

Ships are Big - Boats are Small

For context, the simplest way to define the difference between ships and boats is that one is big and the other is smaller. The official US Naval Education and Training Command guidelines state that you can carry a boat on a ship, but you can’t carry a ship on a boat. Generally speaking, this means that if a craft is large enough to carry its own lifeboats or dinghies, it’s considered a ship.

With that said, there remain some noticeable exceptions to this rule. For example, police boats often carry small life rafts for search and rescue operations. But no one refers to a 30 or 40-foot police boat as a ship.

A more useful metric for this categorization is whether or not a vessel is capable of extended, independent operation. A ship has the ability to carry enough food, water, and fuel for weeks of travel. On the flip side, a boat needs to return to shore frequently or receive supplies from supporting vessels.

But this rule is also not without its exceptions. Commercial fishing vessels, for instance, are commonly referred to as boats. This is despite the fact that they regularly cruise the seas alone for days or weeks at a time. The same is true for large shipping vessels on the Great Lakes, often called “boats.”

An additional feature associated with ships, at least for military vessels, is that they always have a crew and a commanding officer. Even in port, a ship will have at least a commanding officer and a maintenance crew. On the other hand, a boat can be operated without a crew and only has a commanding officer when it’s actively operating.

There’s one common theme to all of these rules of thumb: ships are big, and boats are small (relatively speaking).

Ships Can Traverse The Open Sea

An alternative way to classify boats versus ships is the types of conditions each vessel can handle. Specifically, are they built to endure harsh conditions on open water?

As referenced, a ship can safely travel across the ocean and remain hundreds of miles from land for days or weeks at a time. This requires ships to be well equipped, incredibly stable, and large enough to handle conditions like inclement weather and rough waters.

Boats, on the other hand, can only safely operate in coastal waters. Taking a 30-foot police boat from Boston to London, for instance, would be both foolish and impractical. Aside from that, it simply wouldn’t be stable enough for rough ocean waters, and any large wave would simply capsize the craft at any given point.

But much like the rules noted above, these have their exceptions too. The Great Lakes shipping “boats” mentioned earlier carry thousands of tons, and these boats have to brave storms on Lake Michigan and Lake Superior that rival anything you’ll encounter on the open ocean. Rest assured, these vessels are better designed and more stable than many ships.


At the end of the day, the differentiation between a ship and a boat is mostly a loose rule of thumb with many exceptions and outliers. Many of these categorizations are somewhat open to interpretation and can vary depending on many factors. So while there is no single, hard-and-fast difference between a ship and a boat, we hope some of these differences have been outlined in a way that makes them somewhat easier to identify.