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Recording the meteorological situation in particular is problematical since only a proportion of the mete 
orological data are based on automatically recorded sensor values. Integration of these functionalities in 
an INS therefore has little point - apart from exceptional cases. 
Fundamental areas of this task therefore tend to be of subordinate importance with regard to usage 
within an integrated system, and generally the display of wind and current (true/relative, based on the 
own ship), measured water depth or under keel clearance is undertaken, as well as the fundamental 
weather parameters of air temperature and pressure, relative air humidity and water temperature - along 
with the display of sea chart information. 
4.2.1 Purpose of task 
The purpose of this task is observation of the external influences of relevance to navigational operation, 
with the exception of foreign vessels. 
The parameters to be monitored can be classified in the following areas: 
1. Hydrographic parameters: 
• Tides 
• Current direction/speed 
• Swell: wave height, length and period of wind-affected sea and swell 
• Ice conditions 
• Water temperature 
2. Meteorological parameters: 
• Wind direction and speed 
• Air temperature and pressure, relative air humidity 
• Cloud cover and rainfall 
• Visibility conditions 
The environmental parameters to be monitored moreover include the drift which is produced from the 
combination of wind and current influence. The drift thus comprises the external forces which influence 
the adjustment and control of the set course as disturbance variables. This parameter is generally de 
termined indirectly by evaluating the difference between the movements through the water and move 
ments over ground. 
4.2.2 Functionalities 
From the parameters to be monitored are directly obtained the functionalities which have to be available 
for the purpose of fulfilling the task “Observing the current environmental situation”. The following func 
tionalities are of relevance with regard to integration with an INS: 
1. Observing hydrographic data: 
1.1 Observing the water depth 
1.2 Observing the current direction and speed