How to Check a Boat Tachometer

A tachometer is a dashboard instrument that shows engine revolution. As you accelerate, the engine rotates faster and the tachometer displays the number of engine rotations in revolutions per minute, typically by a needle. These instruments are common in automobiles and boats. A boat tachometer can sometimes become faulty and need to be checked for proper function. Checking your boat's tachometer for proper function can be accomplished with minimal difficulty.

Things You'll Need

  • Wrenches
  • Screwdrivers
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Instructions

    • 1

      Disconnect the boat's battery cables from the terminals. Unscrew the tachometer from the dashboard housing. As all boat dashboards vary, consult your manual for specifics.

    • 2

      Pull the tachometer and its wiring harness out of the dashboard. Inspect the wires to ensure that the wires are all properly connected. Look for any broken, torn, loose or disconnected wires. Patch wires with electrical tape or reconnect wires if necessary.

    • 3

      Turn the tachometer over. Check the voltage switch on the tachometer. Ensure that the tachometer's volt switch is set to 12. Note that this switch is standard on all 12-volt tachometers in order to match the boat's 12-volt battery. If you have a different battery voltage, the tachometer needs to be set accordingly to match the battery pole system. Consult your boat's manual for specifics on voltage requirements.

    • 4

      Reconnect the tachometer and battery cables. Start up the boat. Rev the engine to a low idle and monitor the tachometer. The tachometer needle will rise and fall in accordance with how fast the engine rotates. Let the engine calm down and run without accelerating. A typical engine idle will show a tachometer reading not exceeding 1,000 rpm.