Current 18,000 TEU newbuilds are designed with a cross section close to the limits imposed by the Suez Canal. With a beam of less than 60 m and a scantling draft of 16 m, they are within the limits set by the Suez Canal Authorities (SCA). The Canal limitations may, however, restrict the choices for designers should the industry go for even bigger ships.

The Suez Canal is undergoing continuous development with a substantial growth in capacity, allowing ever-bigger ships to pass through it. The current ship size limitations were published in 2010 – the Suez Canal Authority Beam and Draft tables (Circular 2-2010).

Combinations of beam and draft produce a “bounding box”, limiting the ship’s cross-sectional area. There is no restriction on the ship length at present. What happens if the ship length increases signiicantly beyond 400 m is yet to be seen.

A Suezmax tanker has a draft of 21.1 m and a beam of 50 m, producing a bounding box of 1,005 m2. Liquids are heavy cargo and draft is therefore often the limiting parameter for tankers. The beam is taken from the tables as a function of the draft. Containers are volume cargo and other combinations of beam and draft are possible.

All current 18k designs have a beam of just under 60 m, primarily due to the outreach capacity of port cranes. The maximum draft at this beam is 16.8 m, which is fairly close to the scantling draft of all current designs (16 m), so the cross section of the current 18k design is close to the limits. To increase capacity, the obvious answer would therefore be to increase the ship length. However, length is the most expensive dimension to increase, so wider and deeper ships may be a preferable option to increase capacity.

A ULCS in the range of 20k–24k TEU would in such case beneit from a wider beam allowing for better hull optimisation. A 65 m beam would give a permissible draft of 15 m, which may be an acceptable design draft for normal operations even though the scantling draft would be higher. This could in fact be a not insigniicant limitation.

The Canal has undergone a continuous widening and deepening over the decades, increasing its capacity in step with the general increase in ship size. Is this trend likely to continue? We believe that will depend on demand and on the earning potential for the Canal. So far, the SCA has not published any plans for a further general increase in depth and cross-sectional area.