Airboat Trim Tab Installation Guide

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Lenco Airboat Trim Tabs Installation Instructions

Please read these instructions carefully before installing your Lenco Airboat Trim Tab.

  1. The Airboat trim tab is always mounted in the center of the boats transom with the bottom of the hinge 3/8 inch (.95 cm) up from the bottom of the transom. (See Fig. 1)

    Note: The reason the hinge knuckle is mounted 3/8" (.95 cm) from the bottom of the transom is to allow water to travel along the bottom of the boat and create lift when it is redirected in the tab area. Tabs are also mounted in this manner for protection while on a boat trailer or when being dry-stored. On aluminum hulls, mount the hinge high enough so that when the trim tab is deployed, it clears the bottom lip that extends past the transom. 

    Fig.1  (3/8” up from hull) 

    2) Using a 1/4” (.64 cm) drill bit, drill all hinge holes through the transom. Through-bolt the hinge to the transom using the 1/4” - 20 MS pan head phillips screws, nuts, and washers provided. Use 3M 5200 adhesive caulking to seal all holes and bed the hinge and screws.

Installation of Upper Mounting Bracket and Actuator

  1. 1) To properly position the upper mounting against the transom, first fully extend the Lenco actuator as far as it will go. You can do this by turning the actuator counter clockwise until it free wheels at the end of it’s stroke OR touch the power wires to a 12V DC Source (Example: a drill battery). Once the actuator is fully extended, loosely attach the upper mounting bracket to the top of the actuator and the bottom of the actuator to the lower mounting c-channel’s first hole (the one closest to the hinge) using the bolts, spacers, and nuts provided. Then position the trim tab to the desired level below the bottom of the boat. We recommend 2” - 3” measured from a straight edge or level from the bottom of the boat to the trailing edge of the trim tab. See Fig. 2 

    Fig. 2

    When the trim tab is at the appropriate level, transfer (trace) the outer shape of the upper mounting bracket onto the transom. The upper mounting bracket should be marked where it lays naturally against the transom to prevent binding during functioning of the trim tabs.

    Note: Do not adjust the upper mounting bracket to the right or left, as this will cause binding. Allow the bracket to come to rest at its natural position. 

  2. Remove the upper mounting bracket from the actuator and align to the previously marked location to mark the upper mounting bracket screw hole locations and cable hole location. Using a1/4" (.64 cm) drill bit, drill the three previously marked screw hole locations to a depth of 1-1/4" (3.17 cm).

    Warning: Be sure to check inside the hull before drilling the 3/8" (.95 cm) cable hole. Note: When drilling out the screw hole pattern for the upper mounting bracket, you may drill through the transom. The screws should be installed with 3M 5200 adhesive caulking which will seal the holes when installed.

  3. If all is clear, use the 3/8" (.95 cm) drill bit and drill the previously marked cable hole completely through the transom. Insert the actuator cable through the appropriate hole in the upper mounting bracket until the mount reaches the actuator. Insert the actuator cable through the gland seal until it reaches the rear of the upper mounting bracket. See Fig. 3 If, however, you are prevented from drilling a hole through the transom at the bracket location, using the 3/8" (.95 cm) drill bit, simply drill a 3/8" (.95 cm) hole 4" to 5" (10.16 to 12.7 cm) above the waterline and insert the cable. Cover the hole and cable with a clamshell vent sealed with 3M 5200 for a waterproof and finished effect. 

    Fig. 3

  4. Insert the actuator cable through the transom. With the actuator loosely supported, insert the provided 1/4” - 20 MS pan head phillips screws through the upper mounting bracket holes and into the transom and loosely attach the washers and nut. MAKE SURE TO LEAVE THE SCREWS ONLY PARTIALLY INSTALLED.

  5. Insert the actuator clevis (mounting ear) into the upper mounting bracket and hold the actuator in the approximate installed position. Pass the actuator cable through the transom Removing slack on the cable until it looks like the installation on Fig 3. Finish installing the previously started 1/4” - 20 MS pan head phillips screws, nuts, and washers through the upper mounting bracket and into the transom. We recommend using 3M 5200 adhesive caulking to bed the upper mounting bracket and screws. DO NOT OVERTIGHTEN.

  6. Attach and secure the actuator to the upper mounting bracket using the 5/16-18 X 1-3/4" (4.45 cm) large hex head bolt and 5/16-18 (.79 cm) hex nut provided. We recommend using 3M 5200 adhesive caulking to seal the cable hole on the inside of the transom.

  7. Attach connector ends to the actuator wire pins as instructed in Actuator Deutsch Connector Instructions insert card provided.

For further assistance please use comments form below or visit our contact page.

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