Box boats get bigger and bigger, it always seems odd that a sector of the industry that has such low margins has no trouble finding huge investment sums for new tonnage. The container ship operators tend to be very secretive about their technology and operating techniques, and most of them seem to have their own little twist on things. Maersk did a lot of work on the structural design of the hulls to improve structural rigidity and allow them to reduce the cross section of the box girders, which had big implications for spatial efficiency.
About the environmental concerns, that is something shipping will have to adjust to I’m afraid. Our semi-subs and FPSO’s fell within maritime regulatory authority and were subject to MARPOL and other IMO and national regulations, and believe me even the newer MARPOL requirements are very slack compared to our requirements here in the UK. The Environment Agency watches us like a hawk, all emissions and environmental parameters are continuously monitored and logged on sealed equipment that the EA check regularly, there are upper limits where the plant has to come off line and shut down, no arguments etc etc. I know regulatory supervision in the sort of plant i work in has to be strict, but the EA has the same rules for all UK industry. One of the things our government did was change the EA budget so they rely to a large extent on revenue from fines to fund their operations, to my mind it was a brilliant piece of thinking to link their budget to how effectively they police the environment.

Yes, as a rule the larger the diameter and slower the rotational speed of a prop the more efficient it is, so ships go for large diameter slow turning props where possible. The other factor is that single screw stern designs tend to be more efficient which is a major factor, stern design is just as vital for hull efficiency as bow design. They must have been big clutches 🙂

Neptune,
Thanks for the insights, do the twin screw big box boats use clutches or CPP to enable them to use one engine and run at high speed? I know CPP fitted vessels can do this easily, but I was involved with some large twin screw vessels using direct drive fixed pitch props and if they lost one engine their speed was not much about harbour manouvering speed due to the damage it’d do to the non operational engine and the drag effect of the prop not in use. They had no clutches between engine and shaft so they could not disengage the engines from the props even if they were not running.