The lighthouse Norströmsgrund in the northern Baltic Sea was well instrumented to measure ice forces and ice thickness in the years 1999 to 2003. Load panel and tilt meter data have been analysed to assess global force on the lighthouse during several ice ridge or hummock field interaction events in 2002 and 2003. The size of the ridges, type of interaction, and level ice load are examined, and an attempt is made to assess keel load. The methods of the ISO 19906 Standard are applied to determine the range of ridge forces that may be predicted at the site. ; NRC Pub: yes