MnrAq

Inventories of CO2 emissions from international shipping 2007–2012 35
ship types into two and one classes respectively, and the work vessel type into three classes. As shown in
Table 10, a total of 19 classes are defined.
Table 10 – IHSF vessel types and related vessel classes
Vessel group
Vessel class
Cargo-carrying transport ships 1. Bulk carrier
2. Chemical tanker
3. Container
4. General cargo
5. Liquified gas tanker
6. Oil tanker
7. Other liquids tanker
8. Ferry – passengers (pax) only
9. Cruise
10. Ferry – roll-on/passengers (ro-pax)
11. Refrigerated cargo
12. Roll-on/roll-off (ro-ro)
13. Vehicle
Non-merchant ships 14. Yacht
15. Miscellaneous – fishing 1
Non-seagoing merchant ships 16. Miscellaneous – other 2
Work vessels 17. Service – tug
18. Offshore
19. Service – other
For each vessel class a capacity bin system was developed to further aggregate vessels by either their physical
size or cargo-carrying capacity, based on the following metrics: deadweight tonnage (dwt); 20-foot equivalent
units (TEU); cubic metres (cbm); gross tonnage (gt); or vehicle capacity (see Table 12). The capacity bins are the
same for all vessels in a class. Wherever possible, bin sizes are aligned to the Second IMO GHG Study 2009,
although there are some discrepancies due to differences in the class definitions. It should be noted that the
Third IMO GHG Study 2014 provides higher resolution by class/subclass/capacity bin than the Second IMO
GHG Study 2009. Further details of the approach used and the definitions applied can be found in Annex 1.
1.2.4 Estimating activity using AIS data
The primary purpose of AIS is to report the current location of vessels in order to avoid collisions. Under IMO
regulations (SOLAS, chapter V), all vessels over 300 gt on international transport (IMO, 2002) are required to
carry transmitters. AIS information is reported in different message types depending on the reporting entity
(e.g. vessel, base station) and the nature of the message (i.e. dynamic or static). The messages of interest
for this study are static and dynamic vessel messages (see ITU (2010) for further details of message types).
Dynamic messages (types 1, 2 and 3) report more frequently and provide frequently changing information,
such as location and speed. Static messages (types 5 and 24) contain voyage information, such as draught,
destination and (importantly) the IMO number of the vessel. Static and dynamic messages are linked through
the MMSI number, which is reported in both message types. These messages are collected through receivers
on land (T-AIS) and through a satellite network (S-AIS). Due to temporal and spatial coverage issues, explained
elsewhere (Smith et al. 2012; Second IMO GHG Study 2009), quality can be improved using a combination
of these sources as they offer complementary spatial and temporal coverage.
The consortium used multiple data sources. Annex 1 describes the process adopted for the processing of
the raw data to obtain hourly estimates of speed, draught and region of operation, and their merger into a
single, combined data set for use in the bottom-up model. Information in message 18 transmitted from Class B
transponders was not used to estimate activity and emissions.
1
misc. fishing vessels fall into the non-merchant ships and non-seagoing merchant ships categories.
2
misc. other vessels fall into the non-seagoing merchant ships and work vessels categories.