Recent advances in power electronic drive converters have led to an increased use of this technology for electric propulsion and other variable speed drive applications on marine vessels such as ships and offshore oil platforms. The current and voltage harmonics these devices introduce however have caused marine regulating bodies to introduce strict harmonic voltage limits to ensure that the reliability of equipment and the safety of crews are not compromised by their use. In order to meet these new standards, methods to control harmonics must be adopted. This paper will discuss some of these methods and present an application where a unique wide spectrum passive harmonic filter was used to meet harmonic limits on a cable laying ship that previously required the use of rented generators to allow operation of variable speed drives.