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A jack plate is used to raise and lower the outboard engine on a boat to achieve optimum performance. Ideally, your boat engine is positioned with the propeller just under the surface of the water, producing maximum performance. Too high or low and boat propulsion is severely limited. Also, the additional work required of the engine results in shortened engine life. The appropriate height will depend upon the size and weight of the boat. Different conditions (number of people on the boat, for example) may require adjusting the jack plate to accommodate these changes.
Ensure the jack plate is rated appropriately for your engine size. Jack plates come in multiple sizes and ratings depending on size of engine and your projected needs. Jack plates are rated based on the horsepower of the engine projected for use. Trying to utilize a jack plate not appropriately rated for your engine can result in unsafe boating.
Adjust the jack plate, in our out of the water, using the wrench-like apparatus included as part of the adjustable jack plate. Many jack plates are designed for easy adjustment by simply cranking handles on either side of the plate, moving your outboard engine up or down depending on need.
Manually adjust your jack plate using the slots on either side, which allow for adjustments up and down. If you have access to a friend or other assistant who can help, removing the engine may not even be necessary. While one person supports the engine from directly behind, the other loosens the bolts on either side of the jack plate. Then, raise or lower the engine to its correct height in the jack plate slots and re-tighten the bolts, securing the engine at its new height.
Adjusting the jack plate if no one is available to assist requires removing the engine first. Prior to removal, mark the spot on the jack plate at which the engine is currently to act as a guide to where it should be adjusted. Now, remove the engine and complete the same steps as above: loosening the bolts on either side and raising or lowering as needed, then securely re-tightening the bolts. Re-attach the outboard to its new position on the jack plate.
Use a car or truck jack to move the engine up or down without removing it from the jack plate. Place a board or some other sturdy base below the jack plate. Place the car jack on the base and, using a sturdy length of wood, approximately 2 feet in length, raise the wood on the car jack until it is flush with the bottom of the engine. Now, loosen the bolts on either side of the jack plate, and raise or lower the engine to its new height.
Tim Brugger has been writing professionally since 1995. He has published newsletters, white papers and informational articles for organizations such as IDS Financial Services, Red Chip Review and Western Independent Bankers. His fiction has also been published online. Brugger majored in business studies at the University of Oregon.