Drives & Controls
With a sterndrive or inboard / outboard drive the engine is located close to the transom. Stern drives deliver power via a shaft that goes through the transom to the outdrive.
The out drive or lower unit contains the gearing and carries the propeller. The boat is steered similar to an outboard motor by pivoting this unit and no rudder is required.
It is important to select a propulsion system that is a good match for the hull and motor. Propulsion systems include waterjet or drive shafts and stern drives with propeller.
The correct choice of water jet thrust or propeller is essential to get the best handling and performance. Propulsion types are selected for different tasks and locations.
Exhaust gasses need to freely exit an engine to allow it to generate maximum power. Specialist exhaust systems can be added to improve an engines performance.
A ‘dry’ exhaust system transports exhaust gases to the outside of the hull without cooling. A ‘wet’ exhaust system aims to reduces exhaust gas temperature by cooling.
Trim buttons control hydraulics that change the angle of propeller thrust on outboard motors and sterndrive installations. Outboards can be "tilted up" out of the water.
Trim tabs or interceptors are fitted on the transom to improve sea keeping and performance. Electric motors or hydraulics are used to raise and lower the trim units.
Transom Jack Plates
A transom jack plate is designed to raise or lower an outboard motor vertically at the transom. It can help to improve fuel economy and increase maximum speed.
Jack plates are installed between transom and engine. Jack plates can be hydraulically operated or manually operated and can be used to reduce propeller draft.
Gear Shift Controls
One gear shift control lever is required for each inboard or outboard engine. The gear shift has three defined positions neutral (out of gear), forward and reverse.
Most outboard motors use a combined gear shift and throttle lever. The command from lever to engine can be by cable or electronically, also known as fly by wire.
Engine Throttle Controls
One throttle control lever is usually required for each inboard or outboard engine. The throttle control lever is pushed forward or "throttled up" to increase boat speed.
On multiple engine installations each throttle can be moved independently. Modern fly by wire systems enable two, three or four outboard motors to be synchronised.
Steering Wheels & Helms
Steering wheels for professional craft need to be strong enough to withstand heavy use in rough conditions. Materials include aluminium, stainless steel and composite.
Three spoke designs have more space for the hands to grip the outer rim. Additional steering wheel turn knobs can be fitted to improve speed of turning and manoeuvring.
50 years ago Sir Robin Knox-Johnston made history by…
Ports and the offshore industry are now recognising the potential of…
19 - 20 June 2018
AC75 is the new class of high performance fully foiling monohull racing yachts, to be sailed when New Zealand defend…