Hybrid marine ship propulsion systems are currently being used, and many more are being considered worldwide, including for commercial ships as well as for navies worldwide. These hybrid propulsion systems offer extended ship range and potentially quiet operation with propulsion on propeller shaft line electric motors. When high power and / or speed may be required, the main engines or turbines can be quickly started, and propeller shaft line clutches provide quick and reliable transition from or back to the electric motors.

In the naval marine sector, several ship programs currently use “Combined Diesel Electric or Gas Turbine” (CODELOG) or “Combined Diesel Electric and Gas Turbine” (CODELAG) propulsion. Some utilize Synchronous Self-Shifting Clutches, and some utilize other types of non-automatic friction clutches. Many navies worldwide are considering this type of hybrid propulsion, but variations in machinery arrangements and components can result in significant differences in fuel efficiency, weight, space, first time cost, ship performance, and propulsion machinery lifecycle maintenance with associated cost.

Therefore, serious investigation of the alternatives early in the ship design phase is important and accessing the experience of these existing systems with these components is vital, before settling on a machinery arrangement and its components for a future ship program.

As the old cliché says, “The Devil is in the Details!” Like any system, the success, the reliability, and the ultimate capability often come down to design details and the components chosen. Naval ships are designed to operate, even when damaged or when control or oil supply systems fail. Simplicity and the ability to improvise is often the key to mission success or failure. Synchronous Self-Shifting Clutches, or SSS Clutches, have proven to be “fit and forget” in these propulsion systems, have performed without fail in battle conditions, and this paper will describe the systems, explore the alternatives for propulsion clutches, provide advantages and disadvantages, and will provide experience of SSS Clutches in hybrid propulsion systems.

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