The need of the system has to be announced in cruise planning document "Einsatzplanung" prior to the cruise. The mounting of USBL antenna is executed by ships crew, the operation of the system must be executed by experienced scientific staff. Mounting of antenna takes ca. 45 minutes: removing ice protection of moon pool and lowering GAPS antenna. The reverse procedure for deinstallation takes the same time. In case of sea ice conditions the system must be operated with no ship speed but following ROV or drifting is allowed. In ice free conditions moving of ship is allowed up to 5 knots. Opening angle detecting transponders theoretically amounts to 200 degree. But you need to take the obstruction by means of ships hull into account. In the actual version there is no compatibility to USBL system POSIDONIA (USBL-Box), which is also available on board Polarstern. Online data stream of GAPS is broadcasted via UDP, which can be used by alternative visualization tools (e.g. PosiView) or for seperately logging. GAPS underwater communication is conducted by using various frequencies, interferences with simultaneously operating Echo Sounders are possible. Attention: Submarine cable must be connected and device must be submerged in water through moonpool in box keel before activating GAPS. | 
