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Double
Your Pleasure (21-2)
by Dusty Miller
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 One
of the many benefits of driving a boat powered by twin
engines is the ability to effectively manoeuvre at low
speeds without touching the wheel. While this is often
the case with twin direct drives or V-drives, it’s
often not the case with models powered by twin IO engines.
The propellers of an IO engine are not under the boat.
They are positioned four or five feet aft of the transom.
Since they are so far from the turning center of the
boat, the turning force is minimal. You can put one
throttle in forward and the other in reverse and just
sit there with the engines grumbling away. Eventually
it will start to turn, but it will just creep around
and isn’t efficient or effective enough.
The best way to handle a twin IO at low speeds is to
use one engine at a time and steer with the wheel. For
example, if you’re headed down a slipway in a
crosswind, place the throttle on the downwind side in
gear. That way, the turning force it does provide pushes
against the force of the wind and helps maintain a straight
line. When turning, use the throttle on the outside
of the turn to help bring the boat around. So, when
turning to the port, use the starboard engine and vice-versa.
Using the wheel with an IO can also be a little tricky
at low speeds. First of all, only turn the wheel when
both engines are in neutral. If the wheel is turned
when the boat is in gear, the stern will swing out farther
than expected (and you’ll have to correct it to
go the other way). If the shifter is left in gear and
the wheel is turned the other way, the boat will swing
too far again and end up zigzagging on the edge of being
out of control. Remember you don’t have to turn
the wheel hard to change direction. The only time to
crank the wheel with an IO engine is when you want to
make very abrupt turns. In most cases, a short turn
of the wheel is sufficient.
With an IO, turning the wheel doesn’t just redirect
the flow of water from the prop like a rudder. The wheel
actually changes the direction of the propeller and
there’s a lot more force with a lot more leverage
since the props are so far from the turning point of
the boat.
Practise makes perfect, so here are a couple of exercises
to try. First of all, secure the boat to a strong dock
using three or four fenders and four lines: one each
fore and aft and two spring lines. Now, start both engines
and let them warm up long enough so they won’t
stall when you put them in gear. Make sure the wheel
is centred and put the outside engine in gear. As soon
as you feel the boat move, take it out of gear again.
Now do it with the other side. Move the shifter in gear
and as soon as you feel the prop engage, go back to
neutral right away. I call this touch-in, touch-out
and it’s how to keep the boat under control at
low speeds. Only engage the propeller long enough to
get the boat turning – not moving forward or reverse
– but turning. Also remember, when you engage
the side that’s farther from the dock it will
push the boat toward the dock and the inside engine
will push it away.
Now, take your boat out into open water and practise
turning in its own length. This is easy. To turn to
port, turn the wheel to port (with both engines in neutral,
remember). Whether you’re proceeding forward or
reverse, you always turn the wheel in the direction
you want to go. With the wheel to port, engage the starboard
shifter. As soon as you hear the transmission mesh,
go back to neutral. Now turn the wheel to starboard,
and put the port side shifter in reverse. Touch-in,
touch-out. You’ll notice the bow will start to
turn. To keep turning, repeat the procedure. The boat
will literally turn without proceeding either forward
or reverse. To stop the turn to port, turn the wheel
to starboard and put the starboard side in forward.
The boat will stop.
Twin IO engines won’t offer the same handling
characteristics of a twin direct drive. But, when properly
used with the wheel, they will provide finer control
than a single IO. With a little practise, you’ll
make your boat dance. (Page Top) |
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