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 Most
boats are designed to plane at a particular speed and weight
distribution. However, as weight increases (due to additional fuel,
passengers, or gear) and/or speed decreases, the stern settles down
creating an inefficient, untrimmed condition. As the boat pushes
forward, it creates a "hill of water." In this bow-high
position visibility is limited and the hull bottom is pounded. In
addition, due to significant hull drag and extreme prop angle, fuel
economy is poor. Properly sized Bennett Trim Tabs enable your boat to
overcome this "hill" and plane at speeds slower than designed
planing speed.
As the helm control is pressed, the stern rises, lowering the bow.
Without touching the throttle, speed increases and optimum attitude is
achieved regardless of speed or weight distribution.
Bennett Trim Tabs reposition the boat's bow to cut through the water
reducing pounding, drag, and engine laboring. Repositioning the bow
creates greater visibility which increases safety. Reduced pounding
means greater comfort. Less drag and engine laboring translate into
increased performance, greater speed, and reduced fuel consumption.
With all the advantages and efficiencies created, Bennett Trim Tabs
virtually pay for themselves.
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Without
Trim Tabs
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With
Trim Tabs
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THE
PRINCIPLE OF BENNETT TRIM TABS
Bennett Trim Tabs are two independent, stainless steel,
adjustable afterplanes attached to the bottom edge of the transom. As
the helm control is pressed, the trim tabs move into position.
Water-force on the trim tab surface creates upward pressure, thereby
raising the stern and lowering the bow. The principle is simple. The
results are impressive.
THE
BENNETT ADVANTAGES
Performance
Increase Speed Reduce Pounding Correct Listing
Eliminate Porpoising Offset Prop Torque
Efficiency
Reduce Fuel Consumption Reduce Engine Laboring
Eliminate Squatting
Safety
Improve Visibility Reduce Wake Improve Handling
Reduce Hull Stress
How to
Use Trim Tabs
GETTING STARTED
The key to obtaining optimal results from trim tabs
is to operate them in short bursts and let the boat react before
making another adjustment. The amount of time between corrections is
influenced by the size of the trim tabs and the boats speed. This
will help avoid overtrimming or ending up with one tab too far down when
correcting lateral trim. You will quickly become acquainted with a
boats particular traits.
TAKE OFF
Properly sized trim tabs can
significantly reduce the time needed to get up on plane. They also allow
a boat to keep its bow down and stay on plane at lower speeds. As the
throttle is advanced the stern of the boat begins to squat, lifting the
bow. As the boat accelerates, push the bow down position of the helm
control in short bursts. The boat reacts by the stern lifting, the bow
coming down, speed increasing, and reduced engine laboring. If you over
do it and deflect the tabs too far the boat will end up overtrimmed.
When over trimmed, the steering becomes over sensitive and wants
to pull off course to port or starboard. If this occurs, operate the
control bow up" until the desired attitude is established.
CORRECTING A
LISTING CONDITION 
As a result of uneven weight distribution, prop
torque or wind, a boat runs with a list. Deep "V" hulls are
particularly vulnerable to this condition. Running with a list is
uncomfortable, as well as unsafe. Bennett Trim Tabs operate
independently for effective list correction. To correct for list,
lower the trim tab on the side of the boat that you are listing to.
This will bring the boat level.
TRIM
TABS AND POWER TRIM
It is a common misconception that if
a boat has power trim on the outboard or outdrive it does not need trim
tabs. Power trim can be used to adjust the boat's attitude, but it is
highly inefficient. A propeller is designed to force the boat
forward. When trimming the boat with the prop, the prop must not only
push the boat forward but raise the stern as well. In this situation,
prop slippage is greatly increased thereby wasting R.P.M.'s. Power trim
cannot correct listing, and is ineffective at slower speeds.
Bennett Trim Tabs, in combination with power trim, enable both the hull
and prop to be trimmed independently. The trim tabs trim the hull, while
the power trim adjusts the prop. The result is optimum performance and
efficiency not attainable by the use of power trim alone.
To acheive maximum performance, first
adjust the trim tabs to achieve the desired running attitude. Next, use
the power trim to position the propeller thrust parallel to the water
flow. If necessary, re-adjust the trim tabs to fine tune the attitude.
By observing the boats speed and engine RPMs the best combination of
trim tabs and power trim will be apparent. Trim tab angle indicators and
a power trim angle indicator are particularly useful in duplicating
effective settings.
 
TRIMMING TO SEA CONDITIONS
When running into a head sea you want to trim the bow down so the sharp
forward sections of the boat do their work cleaving the waves. This
provides the most comfortable ride and minimizes stress on the boat (and
passengers). In a following sea the tabs should be fully retracted for
maximum steering response.
CORRECTION
OF PORPOISING
Operate the tabs in very short bursts of about half a second. Continue
until porpoising subsides. The objective is to have only a very slight
amount of tab deflection, just the amount needed to cure the up and down
motion of the bow.
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