|Rena: a box ship, not a tanker (the clue's in the boxes on deck), being assisted by Awanuia, a tanker, not a box ship (the clue's in the pipes on deck)|
Just because there's no passengers doesn’t mean it’s a tanker
The supertanker boom of the early 1970s was news. First there were stories of ships so big that their crews needed bicycles to get around and in one case even a mini (the car, not the skirt). Later, the stories concentrated on the amount of oil they spilled when they ran aground. Thereafter, people tended to assume that all commercial ships were tankers, even if they were carrying coal.
Tanker: noun, a ship, road vehicle, or aircraft for carrying liquids, especially mineral oils, in bulk (Oxforddictionaries.com)
|One captain toured his ship in a mini|
The bicycles, by the way, were either dumped over the side or sold in the next port. Imagine cycling on a sloping, moving, metal surface covered in oily water and you’ll understand why.
Just because it’s spilling oil doesn’t mean it’s a tanker
Most powered vehicles carry oil of some sort. Ships are no exception. Puncture one in the right place, and oil will come out. The same is true of your car or a Boeing 747. It’s only a tanker if it carries liquid as cargo, in bulk, in a tank.
(Etymological aside: the British army in 1916 wanted to keep their new armoured vehicles a secret, so they told anyone who asked that those large objects being carried to the front under tarpaulins were water tanks. They’ve been called ‘tanks’ ever since.)
Just because it’s a tanker doesn’t mean it’s a supertanker
Maritime professionals frown on the term ‘supertanker’, but their own term, VLCC, doesn’t have much gravitas either. VLCC stands for ‘very large crude carrier’ and denotes a two-million-barrel ship, over 250,000 tonnes. There are also a few ULCCs (work it out) over 350,000 tonnes.
The next size below VLCC is the Suezmax (self-explanatory), over 120,000 tonnes. There are very few tankers between 160,000 and 250,000 tonnes because refineries don’t accept parcels of that size. You could just about call a Suezmax a supertanker, but it isn’t one really.
Speaking of ‘tonnes’…
Ships don’t weigh anything
That statement is obviously untrue. I mean that none of the ‘tonnages’ quoted for ships relate to their weight. The two main measurements for commercial ships are deadweight tonnes (dwt) and gross tons (gt). Note the different spellings of tons/tonnes. Naval ships are measured in displacement (don’t call them ‘military ships’; milites is the Latin for soldiers, whose theatre of operations is definitely not the sea).
Gt is a complicated measurement, but in simple terms it is a measurement of enclosed space, having its origin in the medieval wine trade from France to England, when ships were classified by how many tuns (i.e. barrels) they could carry.
Dwt measures how much weight the ship can carry (just like a 40-tonne lorry, which doesn’t weigh 40 tonnes; it can carry 40 tonnes of cargo). Although dwt includes fuel and people, on a cargo ship nearly all of it is cargo.
All ships have certificates that specify their gt and dwt, but which is more informative depends on the type of ship. If it’s a cargo ship, best quote the dwt.
…but use a measurement that means something
Despite the above, other measurements will sometimes be more useful to your readers. It might be accurate to tell them the gt of a cruise ship, but saying how many passengers it carries will mean more to them.
We’ve all seen maritime containers being transported on the roads, so your readers will get a better grasp of the size of a container ship if you say how many boxes it carries. Since boxes come in two main sizes, 20-foot and 40-foot, the figure is usually quoted in ‘teu’ (twenty-foot-equivalent units, so a 40-foot container is 2 teu). Make sure you know if your source is talking about teu or number of boxes.
Oil spills aren’t measured in gallons, and what’s a gallon anyway?
The shipping industry measures oil in tonnes – that is 1,000 kilos. If your readers prefer imperial tons, it’s easiest to convert 1:1. The difference is minimal, and it’s almost impossible to measure an oil spill accurately anyway (short tons – 907 kilos – are mainly used for dry cargo and seldom outside the US).
There are about 6½ barrels in a tonne, but it depends on the type of oil. As for gallons, many papers blithely quote ‘gallons’ without specifying that US gallons are 20% smaller than imperial gallons. It all leads to the conclusion that some writers don’t know or care what the numbers mean.
This piece from AP (http://www.guardian.co.uk/world/feedarticle/9889220) shows a journalist or subeditor getting into a right tangle with their conversions, apparently converting metric tonnes into short tons and then long tons. Sadly, these things are not always checked thoroughly before publication. That begs the question, if the numbers mean nothing to the journalist, the subeditor or the editor, why should they mean anything to the reader? And why are they in the story at all?
Exxon Valdez wasn’t the worst oil spill ever
As I said, it’s very difficult to measure an oil spill. If there’s a fire, some of the oil will be burnt off and some will remain in the ship, whether it’s wrecked or salvaged. But however you measure it, the most famous spill in the past quarter century isn’t the biggest. In fact, Exxon Valdez barely scrapes into the Top 40 (see the list at itopf.com).
If we wanted to measure the importance of an oil spill, we would need to measure the number of rich white people who got upset about it, weighted according to income. As far as I know, nobody is working on such an index. If they were, Exxon Valdez, Erika and Prestige would be much higher up the list (our friends at ITOPF will get you some of the way there).
Titanic wasn’t the worst passenger-ship disaster ever
Again, the rule of ‘rich white people affected’ comes into play. The loss of 1,517 people a century ago was a tragedy, but it doesn’t compare to more recent disasters such as Le Joola (2002, 1,863 Senegalese) or Doña Paz (1987, over 4,000 Filipinos). If we include wartime casualties, the torpedoing of the German refugee ship Wilhelm Gustloff (www.wilhelmgustloff.com) in January 1945 holds the record at around 9,000 – six times the toll of the Titanic.
Moral: fact-checking isn’t easy on a deadline.