Five Commonly Misused Nautical Terms

Maritime work, almost more than any other industry, comes with nearly a dictionary’s worth of unique terms, phrases, and things to remember.

Many of them stretch back for hundreds of years and have remained in popular usage, whether due to the similar construction of boats from then to now or simply for the sake of better understanding what’s being discussed. Even for newer terms that have sprung up through the years, there’s a vast lexicon of maritime and nautical terms and wordage that any crewmember should familiarize themselves with through their time working on the water.

Of course, not all of them are as easy to follow (or to use in a sentence) as others, and keeping up on your maritime lingo is something that could help most ship workers these days. With that in mind, we’ve got five of the most commonly misused nautical terms, what people think they mean, and what they actually mean:

Buoys vs. Markers
It’s the nautical equivalent of the decades-old “magazine vs. clip” confusion held in military branches. The confusion is easy to understand, given how common the terms are used in civilian life, but the difference is a big one. Buoys are always small and white with a blue horizontal band, and are anchored in public waters to demarcate a specific area such as public boat docking. Markers are larger, generally orange and white in color, and have warning signs on them – think something closer to a traffic sign, and you’ve got the right idea. They come with different shapes to indicate needed information, such as areas that ships aren’t permitted to travel through.

Watertight vs. Weathertight
Two types of commonly seen doors aboard larger ships, they serve similar purposes but are distinct enough to warrant different names. The biggest difference tends to be location – weathertight doors are located on deck and near the accommodations on larger cargo ships and are designed to prevent the ingress of water from outside the ship to inside the ship, and are build with a small head of water and open outwards, whereas watertight doors are typically used below decks and are built to prevent the ingress of water from both sides by opening upwards or sidewards, often by automatic means. (Watertight doors are also required by regulation to have some remote confirmation of the opened/closed status below decks.)

Gross Tonnage vs. Net Tonnage
The terms ‘gross’ and ‘net’ tend to get confused in a lot of discussions, mostly financial, but it comes up a lot on cargo vessels as well. Generally used to measure the weight of a vessel, gross tonnage refers to the total weight of every enclosed space on the ship, including non-cargo spaces like the engine room, whereas net tonnage only refers to the volume of spaces designed and designated to carry cargo on the vessel. Further confusing things is the idea that most national or international maritime regulations regulate ships via their gross tonnage, whereas port and anchorage dues are typically calculated by net tonnage.

Swinging Circle vs. Turning Circle
While both of these terms are important to remember for vessel navigation purposes, they mean two distinct things that can both affect how a vessel travels. The term “swinging circle” is only used when a vessel is at anchor, and refers to the theoretical radius in which the vessel is expected to drift (or swing) in a circle while at anchor. “Turning circle”, on the other hand, is part of the vessel’s overall maneuvering characteristics and refers to the diameter that the vessel can turn when the rudder is put hard to one direction. (To put it more simply, swinging circles only take place when a vessel is anchored, and turning circles are measured when a vessel is in motion.)

Ladders vs. Gangways
Finally, the last commonly-confused nautical term is one that affects cargo ships and cruise lines both: the difference between gangways and accommodation ladders. While the purpose of both is to allow access between ship and shore, there’s some differences in how they’re set up and how they do their job. Gangways are rigged at right angles to the fore and aft lines of the ship, never used an angle of inclination greater than 30° to the horizontal, and are mandatory for any ship over 30 meters long. Ladders (or accommodation ladders) are rigged in the fore and aft direction of the ship and face stern, and are generally fixed to the vessel as opposed to being removable or retractable like a gangway.

The number of commonly misunderstood maritime phrases could fill up an entire book, but hopefully these provided a little more context for you!

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