Lightning Shielding Analysis on Ships

Calculations of the expected number of lightning strikes on three ship models are presented with comparative application of various lightning attachment models and stroke current distributions. Depending on the ship structure, on coastal areas, a lightning strike on a ship is expected approximately every two years. Application of the rolling sphere method highlighted as regions exposed to lightning strikes not only high masts but also lower structures in the cases of ships with less dense geometry. A new method for the lightning protection of critical masts that combines a shielding analysis procedure and a statistical lightning interception model was also proposed and applied to specific masts of the ship models in order to evaluate whether shielding from nearby higher masts is achieved and to define the proper height and installation position of a new rod. Proximity effects, interception probability, and choice of the ground reference level arise as parameters that affect the results of the shielding analysis, especially when the equipment under protection is the highest structure on the ship.