Emergency drive systems typically installed in ships with geared medium-speed engines by means of an electric motor connected via a clutch to a pinion shaft in the gearbox (PTI). In normal service the motor serves as a power take off (PTO) shaft generator.
The installation of an emergency drive system in a vessel fitted with low-speed propulsion requires a different solution, due to the high torque, high power, low rpm requirements of the engine.
An innovative take-me-home system was developed by Marinvest Engineering and marine designer Bo Bengtsson for a slow speed main engine on product tankers. It uses the hydraulic power from the Framo cargo system for emergency propulsion. If the main engine breaks down, a hydraulic drive package will be connected to the shaft line in 10-20 minutes.
Emergency drive systems designed for e.g. 6 knots in calm weather are not capable of propelling the ship in rough seas when they are really needed.