The first part of the paper deals with the combination comprising a triple expansion engine, with poppet valves for high and intermediate pressure cylinders, and direct coupled to the main shaft line, and an exhaust steam turbine, to utilize the energy contained in the exhaust steam from the engine, double reduction geared to the main shaft line. In this system, the turbine is to work for ahead direction only; an automatic friction clutch is to disengage the turbine when the main engine is to run in astern direction.Mechanical regilient coupling composed of friction disks and a number of coil springs is contained inside the first reduction gear wheel, and is arranged to take off uneven torsional shocks taking place due to the action of the crank shaft of the reciprocating engine.In the second part, description is given about the combination consisting of a set of double compound high speed engine, single reduction geared to the main shaft line, and a low pressure turbine, double reduction geared to the same line. In this case an astern turbine is also arranged. The exhaust steam from the engine is controlled with special manoeuvering valve to enter into either ahead or astern turbine as desired and the valve is to cooperate with the reversing mechanism of the reciprocating engine.Particulars of the ships having these systems of combination machinery are given in the attached table also the performance data of their maiden voyages are given in another table.A sketch of the design of the machinery space of twin screw engines and its brief description is given in the last part of the paper.