For the purpose of comparing results with the two wavelengths, 3 cm. and 10 cm., generally used in navigational radar, the Defence Forces Research Institute, in collaboration with the Swedish Admiralty, the Royal Pilot Service and the Marine Cartographical Institute, carried out systematic researches and experiments under various conditions, in view of the special meteorological and navigational circumstances prevailing in Swedish waters. Two radar equipments covering these wave-bands were obtained from the Research Institute and installed on board the marine survey ship Gustav Av Klint during the summer of 1947. A separate report has been issued on the results obtained during the summer months.