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the VPPs changed accordingly. Our goal from the beginning was for a fast reaching yacht that could hold h
own on the wind with similar racing yachts of her size. As we analyzed the data, we kept these stronger angl
in mind.
We were now able to pick the top two yachts and from this we started looking at the IRC rating. IRC is a
rating rule that is administered by the RORC rating office in England. It is used world wide. Though the rule i
published and guidelines can be followed to e
sure you keep within the spirit of the rule, the
actual calculations of IRC ratings is kept secr
and contains subjective elements that chang
annually. The only way a designer can 'crack' it
as such, is to study the trends of previous and
current yachts and to then guess where the r
may be heading the following year. The spirit o
the rule requires that designers and owners no
seek means of artificially reducing the rating of
boat. In other words, increasing performance
without a corresponding increase in rating. In
general, the RORC have done a great job in thi
but of course it is the designers job to make th
yacht as fast as possible within the rating. RO
allows designers to get a fixed number of trial certificates per boat per year so we can see how various
changes affect the rating.
We went through that exercise to see how the two yachts rated against each other and from there
were able to see how our VPPs were able to deal with the rating given. It sounds like a lot of work to rea
a goal, but that is our job. And though we come up with our own results and opinions on where the
client should go, another design firm may came up with something completely different based on their
own interpretations. This is what makes yacht designing so interesting. Every yacht has its day and
every designer has their particular way and style.
Westlawn alumni are invited to submit drawings and renderings of designs for publication in
The Mast-
that are “On The Drawing Board.” Selection for publication is a the sole discretion of the West-
lawn Institute of Marine Technology. Designs should be emailed to
Dibley Marine Ltd.
P.O.Box 46-167 Herne Bay, Auckland,
New Zealand
15 Westhaven Drive, Westhaven, Auckland,
New Zealand
Ph: + 6 4-9-940-9745; F a x: + 6 4-9-374-4462 ;