Chichester Yacht Club Magazine June 2018 | Page 19

Many motor boaters were yacht owners in the
past, and they all will tell you, that at slow
speeds yachts and dinghies have much
greater manoeuvrability. The key difference is
the keel or daggerboard, that gives stability
and help with the boat’s pivot point. In a
motor boat the pivot point moves! Going
forward, the pivot point is towards the middle
of the boat, going astern, it is at the back with
the engine.
In fact, at low speeds a small power boat with
an outboard engine will have more control of
steerage going astern than forwards because
of the change in pivot point. So in the queue
for Chichester Marina lock, on a busy and
windy day, don’t be surprised when a motor
boat decides to go astern for a bit - it is to
gain greater control.
Other thoughts about power and boat
handling are this. If the engine is in neutral,
and there is no correction on the helm,
eventually the engine will swing up into the
wind. There are times, of course, when this
can be quite useful, and can be used to get
into a tight spot on a pontoon.
Other times this will work against the boat
and power is required to counter the action of
the wind. Experienced power boaters will try
to put themselves in a position where they
can use the wind as a matter of preference,
but it is not always possible.
Windage
Motor boats suffer from windage greatly and
can very easily be “taken” by the wind. Even
low profile RHIBs can suffer. For example our
8 metre, 1.8 tonne RHIB would suffer from
this particularly coming into Chichester
Marina lock on low water, with the wind from
the south.
The wind would hurtle into the lock with us,
hit the lock gates at the end and tunnel round.
Unless we had enough power on, and were
ready to “catch” the boat, the wind would hit
the bow and turn us sideways...
Now did you know ....that lock is just over
eight metres wide?
I have been sideways in that lock, with the
lock keeper leaning out of his window
saying ..”In your own time madam” - all
because of windage.
Other laws of Physics
OK, these really are to do with the impact of
tide, and momentum, and perhaps the best
way to explain is to relay events that took
place last summer. At the time we were
running “Hot Fish” our 8m RHIB, which
weighed about 1.8 tonnes. At just on tick-over
we would be doing about 6.5 knots. On this
occasion we were near Stocker buoy, on a
falling spring tide.
Hayling Island Yacht Club boats were racing
across the fairway, which is fairly narrow at
that point.
There were multiple dinghies sailing and we
were going as slowly as we could. However,
one dinghy tacked immediately on our
starboard side to come back across the
fairway. He was so close to us that taking the
engine out of gear was simply not going to be
enough to take off the momentum of the boat
given its weight, and the effects of a fast
running falling tide.
With other dinghies all around us, we could
not change course without causing a collision
with a different boat.
So for us, the only way we could reduce
enough momentum and avoid a collision, was
to throw the engine into reverse and hope for
the best.
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