For vessels with dynamic positioning (DP) as the main operating mode, such as diving support vessels, crane ships, and pipe layers, electric propulsion was early taken into use, first with fixed speed CP propellers and later with variable speed thrusters.
The reduction in fuel consumption and environmental emission from diesel electric propulsion compared to conventional mechanical propulsion is significant for vessels with a diversified operational profile.
Savings of 30-40% in fuel consumption annually has been reported from ship owners, and with the increased focus on operation costs and environmental impact from the oil industry, has given a large growth in number of field support vessels, first in the North Sea, and later in other geographical areas.
With the rapidly increasing need for high-speed communication system and a global fiber optic cable network, there has been established a large fleet of cable laying vessels with electric propulsion and dynamic positioning.
These vessels will be configured as DP vessels, class 2 or 3 (DnV [60], Lloyds [61] and ABS [62]), and most will have electric propulsion with a total power demand of 8-30 MW, depending on size and drilling/lifting capability.
