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Kevin Dibley
Dibley Marine Ltd.
As soon as you see the word IRC and connect it with any­thing between 38' and 43', you will be excused fro
thinking heavy production type lead mines. It is this type form that seems to do well under this rule and
until you get into the 48' plus lengths that lighter displacement hull forms can start performing to the rati
The cost comparison of a TP 52 and a 42-footer both in build and the 52 campaign costs are far mo
than triple. We have a group of yachties out there that want their yacht to light up and fly, but are eith
forced to go heavy and slow to have any chance under IRC, or
to a different rule/ handicap system all together.
There is talk from the RORC that th
are going to review this anomaly, but
the mean time we have to work wi
what we have.
Recently we were commissioned to
some preliminary work on a new IRC
footer. We needed to find out where
draw the line in the sand without havi
to go heavy displacement, but not
light that we ended up with a great
sign that could never race to her rati
It had to perform well on the wind as well as light up on reachi
conditions, which most of our coastal races are down here in A
tralia and New Zealand.
The first item on the job list was to review what was currently rac
ing out there in this size range. We looked at designs that have
had decent success in this size
range. Designers such as Christian
Stimson, Mills, Corby, Farr, Ker, as
well as some of the production boats
such as Beneteau. We then started
looking at sail plans until we picked
one that we thought was about right
for the type of racing she will be do-
ing, as well as for general comparison. Now, the real work began with hull
modeling. Using our Maxsurf modeling software, we tried out different scenar-
ios on weight, volume distribution, prismatics, measurement trim, and even
looked outside the square with soft chines and other configurations. We ended
up going through 16 different models. We then put the designs through our
Wins-VPP software to work and from this we can see which yachts were
coming out ahead of the others in various courses such as windward/
leeward, Olympic, offshore, and circular random. Four stood out and from
those, we started looking at appendage and sailplan changes, and how
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12.80m 42’-0”
11.70m 38’-4”
BEAM 3.98m 12’-9”
DRAFT 2.90m 9’-6”
DISPL 5875kg’s 12,950 lb.
17.133m 56’-2”
5.00m 16’-4”
5.25m 17’-3”
19.24m 63’-1”
6.71m 22’-0”
17.30m 56’-9”
6.15m 20’-2”