As we can't do much
sailing this time of
year, its time to
sit down and have a
think about how it
all works!
This month we are
looking at the
influence of the
spreaders!
The length and angle
of the spreaders
and, to a small
extent, the height
of the spreaders
will all affect the
mast. The spreaders
should be long
enough to keep the
mast straight
sideways from deck
level to the hounds.
If the mast
bends to windward,
pointing ability be
affected though the
boat may be easier
to hold upright. If
the mast bends to
leeward, this will
close the slot,
affect boat speed
and make the boat
more difficult to
hold upright.
The length of
the spreaders
control the lateral
stiffness and the
fore and aft angle
of the spreaders
control the fore and
aft bend. The mast
is stiffened
sideways by
deflecting the
natural line of the
shroud outward: the
further the
deflection, the
greater the
stiffening effect.
The angle of the
spreaders affects
the mast stiffness.
When the spreaders
are angled forward
and deflect the
shroud forward of
its natural line the
mast is made stiffer
fore and aft, when
they are angled back
the mast is made
more flexible.
Using different
spreader lengths and
angles the object is
to obtain the
optimum bend
characteristic for
your crew weight and
sail fullness etc.
Mast rams / screws,
etc, are used to
restrict or control
overall bend,
particularly in the
lower region.
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