Who doesn’t want the best of anything and everything? Yes, we all do. We want options and choices, maybe alternatives or possibilities of something not limited to just one thing. Boat owners want these same choices too, in fact an array of choices to be available to them whenever they are planning to own a boat or when it comes to picking engines, otherwise known as a motor or drive. This basic mechanical principle of a boat engine is the same as for any internal combustion engine, such as power cars, trucks, or other vehicles. Of course if you are new to boating or planning a sea voyage, deciding on what type of boat you want to get as well as when picking out engines, is a bit overwhelming with all the several options on the market.
What is Propulsion?
Propulsion is to push forward or drive an object forward. The term was derived two Latin words: pro, meaning before or forward and Pellere, meaning to drive. It is source of mechanical power, and a propulsor, which is converting this power into propulsive force. A technological system that enables an engine or motor as the power source (commonly called a power plant). Marine propulsion (boat) is the system used to generate thrust to move a ship or boat across water. Paddles and sails are still used to sail small boats but modern ships are propelled by mechanical systems consisting of a motor or engine turning a propeller, or less frequently in jet drives.
There are a number of common boat types people in the industry are familiar with, single propulsion engine boats, twin propulsion engines and drives, which are, sterndrive (inboard/outboard drive), inboard motors, and outboard motors, which also have their pro and cons too:
Inboard Propulsion Systems
These are a type of propulsion system that have their engines mounted inside the hull of the boat, usually at the center. How power is created and delivered is similar to how a car engine works. A driveshaft runs from the engine to the outside of the boat where it is connected to a propeller. In an inbound boat, it has a rudder mounted directly behind the propeller to enable steering. Inboard drives can be powered either by gasoline or diesel fuel. One of the grave disadvantages of this setup, is inboard boats can’t be effectively steered or maneuvered in reverse. Unlike outboard boats, inboard boats can be left in the water for a year round. They are cheaper to maintain, have a lower center of gravity for better handling, and have a cleaner transom. Some inboard motors are air-cooled, while others use a water-cooling system-either a fresh-water-cooling water radiator similar to that in automobile.
Outboard Propulsion Systems
This is a propulsion system, which has a unit mounted externally to the rear of the boat that contains the engine, gearbox, and propeller. Outboard propulsion systems are the commonest propulsion systems. Not only does the unit provide propulsion, but it all also provides steering control all in one. They are generally more efficient and you can get more performance per horsepower compared to inboard boats. And they don’t need to be maintained regularly.
Stern Drive Propulsion Systems
This is a twin propulsion system, which has its drive unit or outdrive mounted to the rear of the boat with the engine sitting just forward of the transom, or rear of the boat. The outdrive delivers power from the engine to the propeller. The bottom half of an outdrive has a slight resemblance to an outboard motor. One of the disadvantage of stern drive is that it is difficult to maintain due obstructed accessibility. Maintenance costs are usually higher from year to year.
The Other Types of Boats Engines
Pod Drives: is a system in which the propeller units extend down directly beneath the engine through the bottom hull of the boat. The propellers are set in front of the drive shaft, sob that the boat is actually pulled through the water, not pushed. The efficiency is up to 20 percent. Pod drives are usually mounted in pairs and this allows the boat to be extremely maneuverable. With the pods controlled individually, the boat can spin on its axis while remaining in place, a decided advantage for docking or boating in tight quarters.
Jet Drives: are used in personal watercraft or very large boats, jet drives replace propellers to push a boat through the water using high-pressure air forced out of the stern of a vessel. Jet drives are good accelerators, but quite loud and not very efficient when it comes to fuel economy.
Surface Drives: are specialized drives mostly used by high-performance boats, with an inboard engine that drives a propeller and pierces the surface of the water to provide increased thrust. These drives are used when you want to achieve a high rate of speed.