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Cowper
decided at an early stage that Polar Bound should be built of aluminum
because of its strength-to-weight ratio as well as other reasons. “It’s
better in ice because it’s more ductile; it will bend rather than
crack or tear,” he explains. “And aluminum welding stands
up much better to extreme low temperatures.” Hull plating is more
than half-inch thick, three quarters of an inch where it’s most
likely to come into contact with ice. A honeycomb of closely spaced frames
and stringers gives the whole structure rigidity and enormous strength.
The
builder, New Century Marine in Scotland, specializes in aluminum construction,
but Polar Bound still represented a major challenge. Managing director
Edwin Payne reckons the boat is 12 times stronger than any conventionally
built aluminum boat. His expert team spent nearly 5,000 hours applying
the continuous welding that holds the boat together; there’s more
than a mile and a half of the stuff along the frames and stringers alone.
The
boat’s designer, Dennis Davidson of Murray Cormack Associates, another
Scottish company, gave the hull a rounded, flared shape that, instead
of being squeezed by the ice, should be forced upwards, relieving its
vise-like pressure. The deck and superstructure are also designed to cope
with the worst the elements can throw at them. Deck fittings, such as
the high swan-neck vents and heavy-duty guardrail stanchions, wouldn’t
look amiss on a small freighter. The windows in the purposeful wheelhouse
derive their strength as much from their small size as from the thickness
of their glass and Makrolon polycarbonate construction.
Determined
to install a single Gardner diesel in the boat, Cowper had to buy a remanufactured
one; these classic, famously reliable engines, two of which powered his
old lifeboat, are no longer made. Since mechanics will not exactly be
lining the route of her long voyage, reliability is of paramount importance.
“With a Gardner you shouldn’t have any problems if you have
clean fuel and oil filters and keep the fuel in the tanks clean,”
Cowper says. “I will be filtering all the fuel as it goes into the
vessel.”
The
170-hp Gardner 8LXB pushes Polar Bound up to 9 knots at its maximum
1500 rpm. On long passages Cowper will set the throttle to give 1100 rpm
and about 7 knots, for a fuel consumption of less than 3 gph. With 2,380
gallons in the main tanks and another 900 gallons in jerry cans, the boat
has a potential safe range of about 7,000 miles.
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