Generic ship transport

The category /transport/ship/generic contains data on the greenhouse gas emissions associated with ship-based passenger transport. This category provides CO₂ emissions only and should be considered to represent a useful first point of entry to ship-related emissions. If users are interested in more specific and comprehensive data (which includes CO₂ as well as CH₄ and N₂O emissions) they should see the specific DEFRA category for ship transport.

For emissions methodologies associated with ship-based freighting, see the Ship freighting subcategory.

To use this category, select they type of ship journey using the type drill option. Users can choose from the following options:

• ferry: specifies emissions calculation for average ferry passenger
• by foot: specifies emissions calculation specifically for walk-on passenger
• by car: specifies emissions calculation specifically for drive-on passenger

Next, users can choose between calculations based on absolute travel distances or multiple journeys. The former may be appropriate for single, long-distance journeys (e.g. holiday travel), while the latter is useful for those journeys which are repeated on a regular basis (e.g. commuting).

Calculating by absolute distance

To calculate emissions based on single journey distance, simply set the distance using the distance profile item value. Users can additionally set a multiple number of passengers by setting the numberOfPassengers profile item value. The value returned represents CO₂ emissions attributable to all nominated passengers for the distance travelled.

Calculating by multiple journeys

To calculate emissions based on a number of repeated journeys, users must specify (1) a journey distance, and (2) a journey frequency. To set the journey distance, simply set the distance using the distancePerJourney profile item value. If the distance is not known, a 'typical' distance for ferry travel - of 34 km - can be substituted by setting the useTypicalDistance profile item value to 'true'.

Journey frequency is expressed in terms of a number of journeys per some specified time period, for example ten journeys per week or one journey per month. The quantity of journeys is specified by setting the numberOfJourneys profile item value to a numeric value, while the time period is set using the journeyFrequency profile item value. Valid values for the journeyFrequency profile item value are as follows:

• 'daily'
• 'weekly'
• 'monthly'
• 'yearly'

Users can optionally declare the stated journey frequency to represent return journeys by setting the isReturn profile item value to 'true', in which case the total number of journeys are doubled. A multiple number of passengers can also be included by setting the numberOfPassengers profile item value. The value returned represents CO₂ emissions attributable to all nominated passengers per year.