‘House-forward’ layouts might be the last available option for increasing capacity on new megamax box ship designs, with a 400m by 24m footprint reaching the limits of its potential.
Alphaliner is hedging its bets by suggesting that “close to” 26,000 teu could be achieved within the megamax footprint through optimisation of machinery space and further exploration of a concept by Japan’s Nihon Shipyard, for a series of ONE vessels, of balancing a further stack of containers on the foc’s’le, making 26 stacks in all.
Until a decade ago, containership design generally situated the bridge, engine room and funnels together, which meant bridge crew could easily make their way down to the engine room in an emergency. That changed when vessel designers began to recognise that placing the bridge further aft limited the number of containers that could be stacked in front of it. For visibility’s sake, stacks would have to be tiered toward the bow.
To address this, designers split bridge and engine room, and situated the bridge further forward, unlocking additional capacity amidships, and the ‘megamax’ was born. With this arrangement, ship capacity was able to increase to today’s 24,346 teu.
But recent designs for smaller vessels, notably Maersk’s new 16-17,000 teu methanol series, have attempted to stretch the principle by situating the bridge and accommodation at the bow, allowing every stack behind it to reach the maximum height.
It may be the only avenue left to further expand the capacity of megamaxes within the same footprint, but this may lead to some frightening compromises. For one, in heavy weather, the crew are situated at the apex of slamming and pitching motions, and the bridge and accommodations are not high up enough, so, in heavy weather, water would easily make its way into the crew cabins.
If the ship’s foc’s’le is too low, seawater can wash into the vessel’s holds and cause it to sink bow-first, similar to the case of the Derbyshire in September 1980.
Another issue of situating crew close to the bow is what might happen to them in the event of a collision. And, as maritime veteran mariner Michael Grey pointed out in conversation with The Loadstar, it is a long run between crew bridge and engine room in the event of an alarm.
But, with the Ever Given crisis putting a stop on conversations about making ships longer, the only other possibility is to increase beam: Alphaliner suggests a vessel widened to 25 rows, or 63.5m, “could easily come close to 26,000 teu”.
For this, new and sufficiently wide dry docks would have to be built, rivers dredged and new container cranes would be needed – a fraught proposition, of late. For the time being, then, The Loadstar tentatively suggests shipowners might have to content themselves with nudging 25,000 teu.