Keel bomb
A keel bulb is a streamlined weight at the lower end of the fin keel , Kippkiels or Hubkiels a yacht .
The keel bomb consists of a material with the highest possible density, usually lead or (less dense, but cheaper) iron alloys. It creates a righting moment that counteracts the force of the wind on the rig . When designing the keel bomb, the draft plays an important role: for cruise ships that are supposed to be able to enter smaller ports with shallow water, a shallow draft is often sought. To get the same righting moment, as the lever arm (draft) is decreased, the weight of the bomb must be increased. The resulting increased weight of the yacht (just like the shorter keel fin) has a negative effect on the sailing properties.