Yamaha F20B Owner's Manual

Also see for F-20B: Owner's manual Owner's manual Service manual Owner's manual Installation manual

Contents

Installation31line (keel line) of the boat, and ensurethat the boat itself is well balanced. Oth-erwise the boat will be hard to steer. Forboats without a keel or which are asym-metrical, consult your dealer.EMU26923Mounting heightTo run your boat at optimum efficiency, thewater resistance (drag) of the boat and out-board motor must be made as little as possi-ble. The mounting height of the outboardmotor greatly affects the water resistance. Ifthe mounting height is too high, cavitationtends to occur, thus reducing the propulsion;and if the propeller tips cut the air, the enginespeed will rise abnormally and cause the en-gine to overheat. If the mounting height is toolow, the water resistance will increase andthereby reduce engine efficiency. Mount theoutboard motor so that the anti-cavitationplate is between the bottom of the boat anda level 25 mm (1 in) below it.NOTICEECM01631 Check that the idle hole stays highenough to keep out water getting insideengine even if the boat is in stationarywith maximum load. Incorrect engine height or obstructionsto the smooth flow of water (such as thedesign or condition of the boat, or ac-cessories such as transom ladders ordepth finder transducers) can createairborne water spray while the boat iscruising. If the motor is operated con-tinuously in the presence of airbornewater spray, enough water could enterthe engine through the intake openingon the cowling to cause severe enginedamage. Eliminate the cause of the air-borne water spray.TIP: The optimum mounting height of the out-board motor is affected by the boat andmotor combination and the desired use.Test runs at different heights can help de-termine the optimum mounting height.Consult your Yamaha dealer or boat man-ufacturer for further information on deter-mining the proper mounting height. For instructions on setting the trim angle ofthe outboard motor, see page 48.1. Center line (keel line)ZMU017601