The SKIPPER SD21 is the first of a new generation of Satellite based Speed logs from SKIPPER. It is made to fulfill the basic ISO/IMO standards, as well as the modern IEC standards for maritime equipment and alarm handling. The system uses a Dual satellite antenna capable of receiving both GPS and GLONAS and from these signals can calculate speed over ground, the heading, and using an internal sensor, Rate of Turn. The system is designed as part of the MULTI family of products, and shares a user interface with the other multi products, The SD21 includes a SKIPPER DL1-Multi system to provide and independent but integrated Speed Through Water sensor. The DL1 Multi part of the system has its own manual. As connection and interface is independent of the SATLOG SOG functions.