A Brief Introduction of Outboard Engine

The outboard engine, as the name suggests, refers to a propulsion engine mounted on the outside of the hull, usually suspended from the outside of the raft, also known as the outboard. The outboard engine has high integration and simple installation. It is the first choice for personal leisure and recreational boats. It is also widely used in fisheries, commercial operations and government law enforcement.

According to different energy sources, outboard engines are divided into fuel oil outboard and electric outboard engines.

Fuel Oil Outboard Engines

Working Principle

The working principle of the fuel-type outboard engine is to convert the chemical energy of the fuel into mechanical energy through the internal combustion engine, and then convert it into the kinetic energy of the boat forward through the mechanical transmission and the propeller.

Structure

It usually consists of three main components, a power head, a gearbox, and a propeller.

1. The power head is the core power of the outboard engine and is actually a complete internal combustion engine. The conventional internal combustion engine has a horizontal arrangement of the crankshaft and outputs power in a horizontal direction. The crankshaft of the internal combustion engine of the outboard engine is vertically arranged to facilitate the power output downward. In addition to the crankshaft, piston, connecting rod, cylinder liner, cylinder head, cylinder block, a power head also includes a complete valve train, fuel system, cooling system, lubrication system, intake system, and other components, and so on.

The power head is the part with the highest cost, technical content and weight of the entire outboard machine. 

2. The gear box is located below the power head, responsible for transmitting power to the propeller, and provides a reduction ratio - because the internal combustion engine speed is too high and the torque is small, which is not suitable for ship propulsion,  the gear box is needed to reduce the speed. The gearbox is mainly composed of a transmission shaft, a gear, and an outer casing. Its main performance indicators are transmission efficiency, water resistance coefficient,  reliability and durability. 

3.The propeller is also very particular part. The most basic indicator of the propeller is the pitch. The pitch is defined as the distance that the propeller rotates one turn without a slip; the pitch of the pitch and the screw are essentially the same. When the pitch is large, the thrust required by the propeller is large, and the distance for each revolution is large; and vice versa.

Usually for heavy-duty ships, we hope that the torque provided by the outboard machine is larger, the propeller pitch is larger, and the propulsion efficiency is higher; for very light boats, the torque requirements are not so high, the propeller pitch is smaller, and the rotation speed is higher. 

Electric Outboard Motors

Working Principle

With the maturity of DC brushless motor technology and advances in battery technology, electric outboard engines have also entered the range of people's choices.The electric outboard motor uses a recyclable battery as an energy source to convert electrical energy into kinetic energy through an electric motor.

Structure

The core components of the electric outboard are the motors, the battery, and the control circuit that controls the speed of the motor. Others are the housing, connectors, suspensions, and other value-added components such as GPS chips, battery management circuits, and more.