Catalina Owner's Manual - Chris Craft

Systems
Theory of Operation
Trim tabs are used to modify the running angle of the boat. The Chris-Craft is designed to plane at a particular
speed and weight distribution. As weight increases and/or speed decreases, the stern settles creating an
inefficient, untrimmed condition. In this bow-high position, visibility is limited, fuel economy is poor and
wake is large. Additionally the hull bottom may be pounded by waves. Trim tabs allows the vessel to plane
at heavier loads and slower speeds than the designed planing speed.
Increased trim may improve the ride in a head sea by allowing the bow to cleave the waves, rather than
pound over them. In a following sea, the tabs should be fully retracted for maximum steering response. A
listing condition may be corrected by applying more trim on one side. Too much trim will increase the drag
and cause the bow to “dig in” allowing wave action to veer the boat.
As the owner/operator, it is you responsibility to understand how trim tabs affect the characteristics of the
boat. The Trim Tab Owner’s Manual that accompanies this vessel provides additional operating and safety
instructions, which is not repeated here. However at a minimum:
• Use trim tabs only at cruising speeds.
• Do not use more tab than is actually needed for good performance.
• Do not reduce the running angle less than 2°.
• Do not use the trim tabs when backing or running an inlet. Damage to the actuators and tabs my result.
• Fully retract the trim tabs when trailering the boat or if leaving the boat to sit in the water for any extended length
of time.
• Spend time getting familiar with how the trim tabs affect the vessel.
• Improper use of the trim tabs can cause an accident and/or injury.
Trim Tab Control Switches
There is a trim tab switch for each trim tab (Figure 3-16) and are generally located on or near the helm.
When pressed, the switch activates the pressure pump that moves the trim tab in the desired direction.
Actual location of the switches may vary from model to model.
To correct for a listing condition you must lower the trim tab on the listed (lower) side by pushing the top
half of the rocker switch in a half second burst until the boat is righted.
If the stern of the boat is highly loaded, use both switches to operate both tabs, which lowers the bow when
the boat is on plane.
Figure 3-16. Trim Tab Control Switches
Chris-Craft 3–23