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How Do Trim Tabs Work

Boaters will enjoy many performance and efficiency benefits by adding Lectrotab trim tabs. Lectrotab trim 
tabs improve fuel efficiency, increase boat speed, accelerate shallow water planing, eliminate porpoising, and 
enhance the overall boating experience with a more comfortable ride. 

•           Improved Fuel Efficiency and Faster Speeds

Most importantly, the trim tabs may be adjusted to optimize speed and fuel efficiency. Typically, the 
bow rides high causing the stern to drag in the water at cruising or lower speeds. A boat owner will 
attempt to correct this problem by trimming his outdrive down to bring the bow down. This 
adjustment is extremely inefficient and reduces boat speed and increases fuel consumption, because 
trimming of the outdrive pushes water down to allow the transom to rise and bow to lower. In this 
scenario, the outdrive is not only propelling the boat forward but it is also pushing the bow down. 
The most efficient way to operate the boat is to adjust the tabs to maximize boat speed and level. 
The outdrive may then be adjusted so the prop shaft is parallel to the water to maximize the thrust 
to push the boat forward. 

•          Faster Planing

For shallow water starts, trim tabs allow the boat to get up on plane faster. Faster planing can be 
accomplished by lowering the tabs to the fully deployed position. As the boat achieves plane, trim 
tabs may be raised until the boat is level.

•           Porpoising

Occasionally, an uneven load distribution or certain speeds will cause the boat to “porpoise”. This 

problem can easily be corrected by deploying both trim tabs simultaneously a few degrees until the 

“porpoising” stops.

•           Boat Leveling

Every boat owner has experienced passengers or equipment moved to one side of the boat, which 
causes the boat to lean to one side and leads to difficulty in handling the boat as well as an 
uncomfortable ride. Adding trim tabs to a boat corrects this problem by deploying the tab on the 
same side as the boat is leaning towards which levels the boat for a more comfortable ride. 

•           Head Sea

Rough sea conditions can also be better managed with trim tabs. Typically in a head sea, the boat 
speed must be reduced causing the bow to ride high. The waves will pound and beat the boat 
bottom for an extremely uncomfortable and slow ride. Trim tabs can be deployed to level the boat 
out and allow the hull to cut through the waves for a smoother and more efficient ride.

•           A Beam Sea or Wind

A beam sea or wind can lead to a wet ride. To greatly reduce or eliminate the spray caused by waves 
or wind hitting the boat side, the windward side trim tab may be deployed to raise the windward 
side of the boat. Also retracting the leeward trim tab side may help.

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Summary of Contents for ALC-1D

Page 1: ...ual Stations or Dual Actuators per tab ALC 1D and ALC 2D models ELECTROMECHANICAL TRIM TAB SYSTEMS Linear Devices Corporation dba Lectrotab 11126 Air Park Road Suite G Ashland VA 23005 www lectrotab c...

Page 2: ...Tabs Work 4 Operational Overview 5 Control Box Installation 6 Display Panel Installation 6 Wiring Connections 7 Wiring Diagram 8 Control Box Calibration 9 Verify Connection Operation 9 Automatic Cont...

Page 3: ...n a level plane and ensure a comfortable ride If sea conditions change adjustments in boat speed occur or passengers move about the boat the automatic leveling control system utilizes built in sensors...

Page 4: ...er Faster planing can be accomplished by lowering the tabs to the fully deployed position As the boat achieves plane trim tabs may be raised until the boat is level Porpoising Occasionally an uneven l...

Page 5: ...l to actuators and tabs Control adapts to varying sea conditions In calm seas a list condition is corrected faster than in rough seas This allows for faster tab reaction when needed and avoids unneces...

Page 6: ...facing parallel towards the boat s bow A bracket is also provided for floor and overhead mounting so the box will maintain a fore to aft and upright vertical mounted position See diagram below for mo...

Page 7: ...ve wire from the fuse panel to the green 12 pin plug located that will eventually be connected to the black control box A fuse or breaker must be inline with the 12 or 24vdc supply wire to the black c...

Page 8: ...2D For ALC 1D single actuator dual station display or ALC 2D dual actuator single or dual stations 8 Note For ALC 2D dual actuators per tab connect second actuator in parallel with one shown in diagra...

Page 9: ...n and Operation 1 IMPORTANT After calibration verify the connection by pressing the buttons one by one and observing the trim tabs 2 Press and hold the top button Bow Down Both trim tabs should deploy...

Page 10: ...peeds or in turns ALC reverts back to AUTO mode at speeds above planing and once a turn is completed 5 Press the AUTO button to switch between Automatic and Manual modes 6 Display Shut Down When the b...

Page 11: ...between battery negative and primary station keypad red wire 3 Measure voltage at terminal 1 green plug 12 or 24vdc and terminal 2 battery negative for proper voltage see wiring diagram Replace fuse o...

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