Advanced methods for tabulation of electrical loads during special modes of marine vessel operation

Abstract

Current shipbuilding standards allow designers to utilize traditional legacy methods for calculation of electrical load totals during typical shipboard evolutions by applying load factors based on percent time in operation. The time has come to consider mandating more intelligent techniques of calculating load totals on vessels with electric propulsion systems. For electric propulsion vessels with special operating profiles, using the traditional methods to attempt to calculate loading on components such as bidirectional zonal power sources/loads simply does not work. For vessels with large variable electric loads, such as electric propulsion, the electric power load analysis should be done using stochastic methods for special modes of operation such as dynamic positioning, roll-on/roll-off operations, or offshore petroleum discharge mode. This paper will examine the issue from the perspective of a ship designer and will provide examples of how to apply more advanced techniques for performing load analyses on ships with electrical propulsion systems. Proposed changes to classification society rules and other marine standards will be recommended.