The spreading out of the forebody form from the central vertical plane with increasing rapidity as it rises from the waterline to the rail. Ships with an excessive bow flare are exposed to much higher sea loads than previously expected. Sea margin becomes useless because it is not possible to use the installed power in heavy weather due to too high wave impact loads. A good rule of thumb is to avoid bow flare angle against waterline below 50 (45)° in unlimited service (unsheltered waters) and below 45 (40)° in limited service (in sheltered waters), (figures in brackets showing absolute local minimum).