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History of the design
The park avenue style boom dates from at
least 1930 where it appeared on the America's cupper, "Enterprise".
Even then it was acknowledged than the aerodynamic advantages
of a curved foot mainsail were significant. Ideally the curvature
of the top edge of the boom would match that of the sail foot,
thus ensuring that airflow along the boom surface would not be
"lost " either by reflection or by passing though the
gap between the sail and the boom.
The Ceilidh design
The Ceilidh design park avenue boom (PA
boom) is more conservative than recently seen designs. Flat plates
are used in conjunction with flowing underside and deck curves.
These curves give the appearance of a smooth flowing form, while
not complicating the mould design. As with all booms the strength
is concentrated around the vang position. The Ceilidh design
incorporates this into the mould form so that it is possible
to use a much simpler laminate schedule without concentration
of laminate around the vang position.
To improve the appearance of the boom aesthetically
we ensure that the fore and aft end are of the same depth with
the deepest point of the boom slightly in front of the vang position.
Mould design
With our mould we have ensured that the basic form may be used for a variety of lengths. By altering the depth of the boom during attachment of the top surface the proportions are kept even. This enables us to produce booms from 5.5 mtr up to 8 mtr in length
All tooling is negative to reduce unwanted
filler work. Detailing and reinforcements are added to the inner
surface where required.
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