She rolled badly until fitted with a bilge keel. When designing a bilge keel there are important decisions to consider. In early 2002, microscopic cracks in "Te Mana"s bilge keel and hull plating were discovered. In early 2002, microscopic cracks in "Te Kaha"s bilge keel and hull plating were discovered. Rarely, a ship may have more than one bilge keel per side. The starboard bilge keel was also ripped from the hull, as was the rudder. A ship may have more than one bilge keel per side, but this is rare. A bilge keel is a nautical device used to reduce a ship's tendency to roll.