Outboards may be more difficult to work on for a DIY boater, more expensive, and they limit swim platform area. Multiple engines (three and even four) are becoming common on larger boats, and it's also possible to incorporate joystick systems for easier docking. While two-stroke engines have historically been lighter than four-strokes, that's not always the case anymore. Outboards are available in a vast range of power options from diminutive 2.5-hp models to monsters putting out 600 hp or more. The engine can be bolted directly to the boat's transom or mounted onto a bracket, and some new larger boat models place outboards in a well. Outboards are a convenient package with engine, transmission, and prop all in one. Not your grandad's outboard: Modern engines Good for: planing and high-speed boats such as runabouts, also dinghies and manufacturers are beginning to use them on larger boats. But these cons are outweighed by the advantages of minimal loss of power coming out of the engine, ease of service because most engine mechanics can work on them, and they're available in many sizes, including large diesels. ![]() There is some inherent inefficiency due to shaft angle, they take up valuable room down below, and they're often more difficult to trailer. Recently, joysticks have been introduced that, in conjunction with a bow thruster, make close-quarter maneuvering easy. Inboard engines may be gasoline, diesel, or now even electric-powered. These engines are usually situated low down near the middle of the boat, with a transmission connected directly to the rear of the engine leading to a propeller shaft going down at an angle through the bottom of the boat, with a prop bolted onto the end. The reason that small outboards and single cylinder bike motors can get down to a slow idle is they have a flywheel.Recreational powerboating was built on inboard engines that were little more than automobile engines marinized and adapted for boating. On small powered lawn mowers the mower blade is the flywheel but there still is a need for a governor to help get the motor up to speed. A flywheel may help to do the same thing. If you would try to start them with a load on the shaft and no governor they will stall because they can't get into the power band fast enough. That's why so many have a governor to keep the RPMs up. Small lawn-mower sized one lungers suffer from lack of torque at low RPMs. i dont want to build a fast boat just a putt putt for the marsh and bayou area which we have miles of.You are looking at the wrong end of the RPM band. everybody keeps talking about the rpm's of the engine. i have several motors to choose from but im using the honda if i can. and the build will be a larger piroque which is callled alot of other names but it is a flat bottom type skiff. I was kicking that idea around but what can i seal the transom with with that small of a shaft. If you want to get into the stuffing box and the thrust bearing we can get into that too. You are also going to be close to a lot of heat and a lot of noise. Since you are the first to try this on a pirogue I can only say a proper setup (motor gearbox and drive shaft) will require a lot of space for something as tight as a pirogue. Lastly, if the motor is going to come up to 1500 RPMs immediately and there is no way to disconnect the prop the boat is going to do a lot of lurching before you get away from the dock. ![]() If you spin boat props too fast they just stir up the water and don't give the expected push. Outboards have a 2-2.5:1 gear reduction so the motor is in it's operating range and so it the prop. ![]() Then there is the problem of mating motor speed to prop speed. The problem is small motors don't have any low end torque, That's why most of the modern units have a governor to keep the RPMs up. I don't know what a 49 Clinton is but if it's like a 6 HP Techumsah or B&S it's a tough puzzle to make work. Sounds like you want to revisit the lawnmower-motor-in-a-boat trick. To advertise, take a look at WoodenBoat Advertising, or use your Google Adwords account if you want to advertise on the Forum. Selling/self promotion postings are verboten on the Forum. No need to register unless you would like to participate, although some images will only show if you are registered/logged-in.īefore you can post: click the red register link or the register tab, above, right. You'll find answers to the frequently asked questions as well as basic rules. To get WoodenBoat delivered to your door or computer, mobile device of choice, etc, click WB Subscriptions.Ĭheck out the FAQ. The Forum is a free service, and much like the "free" content on Public Radio, we hope you will support WoodenBoat by subscribing to this fabulous magazine. The WoodenBoat Forum is sponsored by WoodenBoat Publications, publisher of WoodenBoat magazine. i want to build a pirogue with a inboard motor!!!! need all the advise of the masses.
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