Dear KiwiRail,

It has long been understood that reducing the operational speed of ships is an effective way to improve efficiency. To illustrate the point, this IMO paper identifies ship speed as the most essential factor to achieve significant emissions reductions:
http://www.imo.org/en/OurWork/Environmen...

It has been broadly claimed that the new vessels will produce fewer emissions, however, it has also been reported that the new vessels will be capable of three return voyages per day. Because of the distance between Picton and Wellington, this raises the question:
At what point in the design process was it determined that the vessels would be able to complete three return voyages per day? In other words, has the vessel design been optimised for efficiency, or was it stipulated that the vessels must be capable of three return voyages per day?

The total fuel consumption for the Interislander ferries given earlier was 31,342,289 litres. This equates to an average daily production of approximately 267 tonnes of carbon dioxide. Has the average daily production of carbon dioxide for the proposed new ferries been calculated? If so, what are the projected emissions?

Given the current level of concern over global warming, the 30-year lifespan of the ferries, and the hundreds of millions being spent, it seems fair to expect a detailed report on the emissions aspect of the vessel design. Is there one available?

Yours faithfully,

Brent Yardley