OWEN
CLARKE ON DESIGNING
THE M65
The M65
production (series) mini-transat design is to be built and marketed
in North America by The Mini Store,
a company formed in 2004 to bring the Mini to the North American
market. The boat will built to the highest standards, using the
latest production techniques including the hull, deck and other
tooling being milled from the solid using the latest CNC cutting
technology. Owen
Clarke Design has produced the complete design
in a 3 dimensional format to suit this build method.
The yacht itself has been over twelve months in conception so
far and is a natural progression to Owen
Clarke Design's previous work and involvement in the mini
class. The program of hull development and vpp analysis we have
just completed has resulted in the yacht specifications attached
below. Fundamental to this work has been the series of tank testing
we undertook two years ago in co-operation with Ian Campbell of
the Wolfson Unit, Southampton University
for the Open 60 Ecover.
With new models, this testing period built on the knowledge gained
during previous tank testing on the Kingfisher
and Hexagon programs. In
this latest series of tests one of the areas we were specifically
investigating was the relationship between chines, close to the
static waterplane (as opposed to higher up the hull surface) and
the resulting increase in static and sailing righting moment with
respect to drag. It should be borne in mind that every class and
rule is different in its treatment of beam, draft, sail area and
displacement for instance. IRC in particular leads to the design
of relatively short rigs, heavy and narrow boats that are at the
opposite end to the Open Class fleet and therefore the approach
and results of any work is likely to be somewhat different.
Nevertheless, Owen Clarke entered
the design phase with an ‘open mind’ as it were and
even looked at some rather unlikely candidates to test the water
and to be absolutely sure we weren’t missing a trick. This
included some of the narrower hull derivations we looked at during
our Volvo 70 and
TP 52 work with
Clay Oliver. Our initial desire was to ‘break’ the
cycle of maximum beam designs in the mini class, especially since
the production boat rules do not allow water ballast, canting
keel and has no ten degree rule. We were in fact able to produce
a design at 2.8 meters that we believe was overall faster than
any of the 3 meter wide mini hull forms we’d used or seen
before. Inexorably however with more time we were able to surpass
those and the final hull derivation at 3 meters represents we
feel the highest performance all round hull that we can develop
at the moment for this fixed keel rule.
Notably as with the route we finally developed with our Open 60
Ecover have opted for an
even harder turn of bilge, flatter topsides and powerful aft sections,
but without the marked detail of a chine low down at the turn
of the bilge that can be seen on some other boats. In the end
‘minis’ have a high sail area to displacement ratio
with greater speed potential than their equivalent size ‘sports
boat cousins’. Without the brake of any rating rule being
applied to them they are hungry for righting moment to offset
their impressive sailplans that see them fully powered up at relatively
low wind speeds. Added to that, once heeled and tracking on the
leeward of their twin rudders the wetted surface area and waterline
beam diminishes quickly and the heeled waterlines take on a clear
sweet form. Like it or not, these fat little boats with large
sail areas are quick, yet well balanced and highly controllable,
just like their longer, world girdling Open 60 cousins.
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