Theory Of Operation; Trim Tab Hydraulic System; Trim Tab Hydraulic Pump; Trim Tab Reservoir - Chris-Craft 2014 36 RH Corsair Owner's Manual

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 cylinders and tabs may
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 Hydraulic System

The trim tab hydraulic system is comprised of the following components:
• Hydraulic Pump
• Reservoir
• Hydraulic Cylinders

Trim Tab Hydraulic Pump

The trim tab hydraulic pump is a 12VDC electric-driven pump. When activated, the electric motor
pumps hydraulic fluid to the hydraulic cylinder located on each tab. The high-pressure oil drives the
piston downwards and pivots the aft section of the trim tab down below the bottom of the boat.

Trim Tab Reservoir

A hydraulic reservoir is built into the base of the pump. Fluid is drawn from the reservoir when the tabs
are driven downward and returned to the reservoir when the tabs retract.
Verify fluid level in the hydraulic pump reservoir on a regular basis. With the trim tabs completely
retracted the fluid level should be about two (2) inches from the bottom of the reservoir. To refill, re-
move lexan cover and filler plug located at the front left hand corner of the reservoir. Fill with any type
of Automatic Transmission Fluid (ATF) only. Brands of ATF can be mixed.
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Systems
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