Panamax, Neopanamax, Suezmax
The most important ship sizes are not engineering limits, they are the dimensions of three waterways.
Read it →The ideas behind the numbers.
Every spec table on this site assumes you know what gross tonnage means, why a Panamax is that exact shape, and what the circle painted on every hull is for. Here is all of it, plainly.
The concepts
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Gross tonnage vs deadweight
GT measures volume, DWT measures lifting capacity, displacement measures weight, and mixing them up ruins every comparison.
Read it →TEU
One TEU is one twenty-foot box. Everything about modern trade is counted in it.
Read it →LOA, beam and draft
Length overall, width, and depth below the waterline: the numbers this whole site is drawn from.
Read it →The bulbous bow
The bulb under the bow cancels the ship's own wave, worth several percent of fuel on the right hull.
Read it →The Plimsoll line
The circle and lines on every hull are a legal maximum-depth gauge, 150 years old and still saving lives.
Read it →Deadweight tonnage (DWT)
The single number that tells you a cargo ship's earning power: everything she can lift, in tonnes.
Read it →Displacement
A ship has no scales, so its weight is measured by the water it pushes aside, Archimedes, at 400 metres.
Read it →Air draft
Draft is how deep a ship sits; air draft is how tall she stands, and it decides which bridges she can pass under.
Read it →Azipod & podded propulsion, explained
The biggest cruise ships have no rudder and no propeller shaft. They have pods that spin 360 degrees.
Read it →Block coefficient
One number from 0 to 1 that captures the whole trade-off between speed and cargo.
Read it →Panamax to Megamax
The box ship generations, named for the chokepoints they were built to fit, or to break.
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