Presentation of the Z-Drive
The Z-Drive (also called stern-drive or sterndrive) is a hybrid system, half outboard, half in board. It is an inboard propulsion (the engine is installed inside the boat) with a base similar to that of an outboard equipped with propeller(s) mounted on the transom.
The latest generations of bases are equipped with two counter-rotating propellers that provide much higher torque, better responsiveness when manoeuvring (especially when reversing) and better directional stability when sailing.
In this propulsion system, it is the base plate that rotates to make the steering, there is no rudder (like an outboard).
This propulsion system is named after Z by the 2 angle gearboxes that give a Z shape to the drive shaft. Cross-section view, the transmission forms a Z.
Like an outboard, the base can be raised. This allows the pilot to adjust the trim setting to get the most out of his engine. It is also an advantage during stranding or transport. The propeller can come out of the water.
The Z-drive is suitable for medium-sized boats with engine powers up to 400 hp. Higher powers are entrusted to other modes of propulsion.
Uses of the Z-Drive
The Z-Drive offers increased performance and is particularly suitable for fast boats with a planing hull. It is also the most commonly used propulsion system on boats from 6 to 12 m long such as runabouts, dinghies, small cabin cruisers and even the largest semi-rigid or open hulls.
Advantages of the Z-Drive
- Engine placed on the rear not disturbing much the arrangements.
- Longitudinal centre of gravity of the retreated vessel
- Maneuverability
- High performance and speed
- Silence if the engine is well soundproofed
Disadvantages of the Z-Drive
- Limited power and boat size (max. 400 hp)
- Maintenance requiring water to be removed (for the revision of the subbases)
- Many mechanical parts requiring maintenance
