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How to adjust the trim tab on an outboard motor?

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It is vital to learn about why a trim tab is needed, as it plays an important role in understanding the whole procedure. Usually during boating, different pressures are formed at the top and bottom of the propeller and this is referred to as wheel-walking. The rotation of propellers causes a pressure difference, which in turn created a dray under water. All of this results in a walk like motion of the boat. Steering or counter steering does not eliminate the wheel walk effect, and hence a trim tab is used. It counter affects the wheel walk motion and ensures that the boat moves smoothly.

Simple Ways to Adjust a Trim Tab on an Outboard Motor: 9 Steps

The first step is to observe the intensity of wheel walking. This will help you in determining the adjustment required for trim tab. You should observe the turning of boat by the effect, and the direction it turns to. If it turns in the opposite direction to the propeller rotation, it needs more tab angle and vice versa. After this use a screwdriver to remove the anti-ventilation plug from the top on a stationary boat. Then securely hold the trim tab in position and loosen its bolt. Give the tab rotations in the right direction and then tighten it firmly.  Lastly, install the plug back and start the boat again. If you think it still needs some adjustments, repeat the process again.

There are a lot of factors that affect the correct placement of trim tabs, and hence you can never get it right on the first try. The correct trim tab adjustment with lead to a straight boat track, especially if the steering becomes useless. Driving a boat with the wrong trim tab adjustments is dangerous and might lead to accidents. The waves are met on the broadside, instead of the strong bow section, which might cause the boat to flip over. Moreover, added fuel energy is taken to bring the boat back on its original direction. The boat might face uncontrollable rolling and the passengers might be thrown off into the water. Hence, you have to be very careful with this procedure. The only tools you will need are screwdrivers and a lot of time.

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