This isn’t as effective or efficient as simply reversing the direction of rotation on a normal propeller, and the results can be sluggish and difficult to control. Jet boats aren’t too hot when travelling in reverse either given the jet can only be directed aft, you’re reliant on the redirection of thrust as a result of lowering the deflector plate over the jet exhaust. Thus, lower speed = poorer directional control. The reason for this is that the effectiveness of the directional control of the ‘jet’ (the flow of water expelled by the jet that provides thrust) is more or less proportional to the speed. Whilst jet drives operate well at speed, when it comes to travelling slowly they aren’t great at all. Just be sure to hold on tight if you ever do this! Why so? Well by slamming the deflector plate over the jet stream and immediately reversing the flow of water you get a much more immediate effect than having to wait for a prop to get up to speed in reverse. In addition if you ever need to stop quickly, then in theory a jet drive is the best means to do so. As mentioned above, they’re great in shallow waters, but inboard jets can also be backed up on to beaches given the absence of any protruding parts including rudders.Īt very high speeds jet drives have been documented as being more efficient than props, and they’re certainly quicker to accelerate. Jet drives offer a lot of practical advantages over propeller driven stern drives or outboard motors, mostly related to the fact that they are safer in conditions where impacts with foreign objects are likely. As such jet drives are perfect for flat bottomed vessels (Jon Boats) used in shallow, rocky rivers, or in applications where personal safety around the prop would be an issue, such as when water skiers climb in and out of the stern of the boat. The impeller of a jet is generally a smaller item than a prop designed for a boat of the same size, and being fully encased, it is well protected from its environment. Well in simple terms jet drives are great, but only in very specific circumstances, much like airboats. Your choice with the I/O will be limited to whatever the dealer has in stock.Off the top of my head there are 3 ways of propelling a boat, either through the use of a conventional propeller, an impeller (or ‘jet drive’), and aircraft style propellers typically found on flat bottomed air boats used in marshlands where below waterline propulsion is impractical.įor most of us the choice will come down to propellers or jet drives, with props generally ruling the waves in most harbours.īut why is this the case? Why don’t jet drives enjoy the same level of popularity? If you are shopping late in the season and don’t want to wait for your boat to be manufactured, an outboard style boat can be powered with any brand of motor you prefer. If a large horsepower I/O engine is shoe-horned into a boat, gaining access to perform routine maintenance may be difficult and more costly as well. This is because there are more tune-up parts required for the I/O. Routine maintenance is generally less expensive for the outboard motor than the I/O. ![]() However, the cost of repowering may be higher due to additional labor costs required when installing a different horsepower engine. Initially the I/Os are less expensive than outboards. Cosmetically they are out of sight and enclosed in an acoustically padded engine box which reduces the operating sounds. ![]() Within the last few years, they have become available with electronic fuel injection.īecause I/O engines are an integral part of the boat they will usually take up more cockpit space than the outboard. I/O engines have always been four stroke engines. ![]() While there are still many carburetor two stroke motors available, the new technology (because of EPA legislation) is moving toward electronic fuel injected motors and four stroke engines. Outboard motors can be found in an assortment of styles. Because of its easy installation and removal, it is often preferred by boaters who wish to keep the hull but repower using the latest technology. What are the advantages and disadvantages of each? JZ, Hicksville NYĪ: Dear JZ: The outboard engine is a self-contained unit mounted on the transom of your boat. Q: Dear Boat Talk: The new boat I have been looking at is offered in outboard and I/O versions.
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