When
it comes to driving a boat, there is nothing more
aggravating than trying to steer one that has a serious
list or labors too long before coming onto a plane.
What
might aggravate the situation even more is if everyone
aboard decides to move to the rear of the boat before
you are able to accelerate onto a plane.
Regardless
of the size of the vessel, excessive weight concentrated
in one area will generally impede how long it will
take a vessel to come to a plane- if it can come to
one at all.
Trying
to see over the high rising bow of a boat lugging
along, desperately trying to "break over,"
and not knowing what is in the pathway as the minutes
seem like hours before sight is regained, can be more
than just a hairy dilemma. Of course, this might not
be a problem, as far as being able to see, if you
happen to have a tuna tower with which to navigate
your vessel.
But
you say you do not have that problem because of having
a plenty of horsepower. Your boat slingshots you out
of the hole like a dragster seeing green lights.
That
could be true for some, but that still might only
resolve the "planing" problem. What about
lateral control?
Even
boats with the most powerfully equipped engine(s),
too much weight to either side can cause a listing
problem while underway. Such problems can only cause
a poor ride, hard steering, exorbitant fuel consumption,
and unnecessary wear and tear on both engine and lower
unit parts.
Some
have even thought that such problems with planing
and lateral control are just something that comes
normally with boating and are non-rectifiable. Others
have even been under the false impression that power
trim is the whole answer to planing faster, thus many
either order their boat equipped with such or have
a unit added after the fact. In either case, no boat
is complete without it.
Sometimes
the answer for faster planing may additionally lie
in having power trim tabs and a hydrofoil stabilizer.
You know, that ugly looking whalelike fin that bolts
on to the outdrive unit. That piece of plastic (metal
in some cases) that many have reasoned to themselves
couldn't work because if it did manufacturers would
already have them on outdrives to begin with.
To
further help you appreciate that such reasoning can
be misleading, ask yourself why it took so long after
the invention of the automobile to find out that aerodynamics
play an important factor in fuel efficiency and handling?
The
simple truth is that it often takes awhile before
inventions are accepted by others as really workable
solutions.
Let's
consider three components that will affect the planing
and lateral control of your boat: Outdrive trim (power
or manual), trim tabs (power or manual) and hydrofoil
stabilizer. These three devices all must have moving
water for them to function. Understandably, the faster
the water moves around them, the better they will
perform.
It
is probably safe to say that most boatmen are familiar
with the function and importance of a properly trimmed
outdrive by either manual or power activation.
For
those who don't know, the trim device for the outdrive
will control how the boat moves through the water
by controlling the tilt of the outdrive and thus will
either move the bow of the boat down or up correspondingly.
For
example, if you move the trim switch on a power trim
unit to "In" position, the outdrive will
move toward the transom and will cause the bow to
move down simultaneously, placing more of the boat
in the water. The opposite will occur if the boat's
outdrive is trimmed to the "out" position.
Generally, the trim switch will only allow a 15 degree
movement out from the transom when the boat is underway
or over a given RPM so that the prop is always submerged
along with the water intake ports.
The
outdrive trim on any boat, whether it be manual or
hydraulically controlled, will ONLY move the bow up
or down and will have no control on the lateral position-
list to either side.
The
principle function of this device is to allow the
driver to control and adjust the planing of the vessel,
fore and aft, according to weight aboard and prevailing
sea conditions.
In
rough or choppy water an outdrive trim unit should
be adjusted to move the bow more down than up, so
that the hull is more in the water and able to nose
through the waves. This will also keep the boat from
leaping out of the water at each wave encounter.
Tuning
the outdrive trim and speed of the boat as it travels
through the water should be done gradually as you
attain the best possible dry ride while maintaining
reasonable comfort for those aboard. Under ideal conditions,
efficiency is best when the outdrive unit is positioned
to maintain near levelness. Under the same conditions,
over trimming the outdrive to cause the bow to come
up too high will result in poor fuel efficiency, cavitation,
and cause the boat to porpoise.
Also,
consideration to loading the boat in a level manner
will also be best, rather than resorting to extreme
adjustments of tilt angle. It must be noted that steering
controllability will be hindered if the outdrive is
over trimmed to either the "in" or "out"
position, whether moving at low or high speeds; the
latter being more evident.
The
benefits of having a power-driven trim on an outdrive
as compared to manual type should be obvious. But
there is even more that can be done to your boat that
will affect the way the hull moves through the water-
even if you already have a power trim unit.
You've
read the claims about hydrofoils: “Advanced
Hi-Tech design developed by computerized aerospace
engineering .... Gets on plane in half the time without
bow pop-up .... 40% fuel savings .... Gives smoother
ride, eliminates chine walk and porposeing, and capitation."
(Note: Hydrofoils have been known to cut fuel economy.)
Upon
reading such, you've also thought, how can a piece
of molded plastic, bolted to my lower unit, achieve
so much? Seems like a lot of hype!
As
earlier alluded to, those who have added this amazing
winglike contraption to their outdrive have found
it to do exactly what had been claimed. Most of us
realize that what sounds too good to be true, probably
is. That's because we, sad to say, we live in a world
full of flimflams and money-making schemes; thus,
it is often hard to see through some claims until
you have been victimized.
However,
this is not the case with this invention and, those
to whom I spoke, were totally astounded by the drastic
improvement of their boat's ride and performance.
When
we think about the theory behind the function of this
winged device, coupled with the movement of the outdrive
power trim, you can see how more area contact with
the water is made by expanding the area of the cavitation
plate.
This
principle is not new, in that airplanes have been
using similar devices on their wings. The only difference
here is that instead of air flow there is water flow
passing across the winged area. The outcome is a more
effective response when adjusting the power-trim angle
and a drastically improved response time for getting
onto a plane- with little or no hindrance as to where
the weight is positioned in the boat. Thus far, we
have considered the power trim device and the hydrofoil
stabilizer. There is yet another planing device that
is most useful and will do what the previous are unable
to accomplish. This device is called trim tabs. They,
like outdrive trim, come in either manual or power
type; the latter is of more benefit and convenience.
Theoretically,
like airplane flaps, are attached to the lower edge
of the transom area at or near each side of the hull.
The power type are controlled from a switch at the
cockpit and can move the tab flaps independently,
either up or down.
Ironically,
more than a few people have seen this device as unnecessary
if already possessing either power trim and/or hydrofoil
stabilizer. Perhaps this is due to not fully understanding
the purpose of each device. First of all, power-trim
tabs trim the hull, while outdrive trim trims the
prop. It is true both will move the bow up or down.
But, the trim tabs will move the lateral position
of the boat as well as positioning the bow up or down.
Outdrive trim can only do the latter. So, if passengers
or gear are disproportionate, you do not have to keep
shuffling everything to balance the ride.
Trim
tabs also enable you to plane your boat at lower than
normal planing speed. This means that when you take
off and the trim tab flaps are down ("bow down"
setting), the back of the boat will rise instead of
lugging down, hence, producing an almost instant plane.
Very beneficial when trying to get onto a plane in
shallow water areas.
This
device, like outdrive trim, needs to be finely tuned
both to achieve the best possible ride, including
lateral stability, by moving the switch to affect
either port side or starboard side levelness. For
example, on take off, when the flaps are down ("bow
down" setting) and the boat is brought to a plane,
it will be necessary to readjust the flaps to adjust
the bow up or the boat will have too much water drag
which will cut fuel economy.
A
quick and easy way to get a basis for proper trimming
of both trim tabs and outdrive is to first move the
trim flaps to "bow up" position (flaps to
the extreme up position) and adjust outdrive trim
in all the way. Then, accelerate the boat onto a plane
and proceed to adjust the outdrive trim to a comfortable
planing position- prop path to or near 90 degrees
to water-flow level. Next move both trim tab flaps
down ( "bow down" position) until stability
is achieved without nosing the bow too low. The boat
should always be trimmed fore and aft before correcting
a list.
If
there is any listing to either side, try adjusting
the bow up by pushing the trim tab switch to "bow
up," either port or starboard side accordingly.
If not affected by that, push the trim tab switch
marked "bow down" on the side that is too
high up, until the bow laterally levels.
Extreme
caution should be taken when moving the flaps of the
trim tabs to maximum position while underway, since
steering maneuverability may dangerously be impeded.
The
advantage of trim tabs over just having outdrive trim
is that if your boat is encountering a choppy sea
condition which is causing the waves to pound either
off the starboard or port bow, you are able to laterally
lift the encountering side slightly to reduce pounding
and over spray.
There is perhaps another misconception about the employment
of trim tabs on boats without outdrives- that is inboard
motor boats that utilize rudder(s) and shaft driven
prop(s). Some boat owners having non-outdrive type
vessels have unfortunately thought that the addition
of trim tabs would give them the ability to lift the
bow of their boat beyond that which it previously
had before trim tab installation.
This
is not true! In such cases, the only thing trim tabs
will do is to trim the boat down from the previous
position and to give more lateral stability where
needed. If more bow up is needed, the weight distribution
of the vessels load could be placed more astern, thus
giving a broader range of trim tab angles to deal
with. Likewise, boats with outdrives, power trim,
and hydrofoil stabilizer can only expect to trim their
boat up only as high as they could prior to trim tab
installation.
Certain
hull designs are more influenced by trimming laterally
than are others. Trihull boats normally are broader
in the front, which gives them more buoyancy, making
them less apt to nose dive in rough seas. Though this
is an advantage, it also can make for a rougher ride
and, with trim tabs improperly adjusted down too far
on one side, along with having rough seas pounding
it cattycorner, may cause stress cracks and/or structural
damage to this type of hull.
Deep
V boats are also affected by extreme trim tab lateral
adjustment, in that the hull will almost tilt to such
a degree to either side causing passengers as well
as gear to perhaps fall overboard. And, as previously
mentioned, helm control loss with unexpected direction
change.
Nevertheless,
having planing devices on your boat will give you
added advantages. Getting use to adjusting them properly
takes some practice, but generally becomes second
nature after a short while.Bottom line is that trim
and hydrofoil devices are the easiest and quickest
way to dramatically improve your boat's performance
at a price that's right.
Check out JerryLabella.com
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