Dear A class member,

As you all know, the IACA held a ballot in August 2001 with regard to the
hydrofoils? issue. A large majority of IACA members, including myself, chose
to rule out (previously permitted) hydrofoils from the A Class Rule.
At present a small group of A Class sailors are deftly trying to get round
the wording of the new rule, which clearly states that ?Hydrofoils shall
not be permitted in the ?A? Division, by proposing artful interpretations
of this latter.
In fact, the sole meaning of this rule is that any device that generates
a lifting force that can reduce the displacement of an immersed hull must
remain prohibited.
Therefore, and since it is without doubt that any inward-canted or round
boards generate a sizeable lifting force proportional to the canting angle,
(in demonstration of my statement I have below attached calculations by
Mr Giorgio Bergamini (Engineer), who is a member of the ISAF Multihulls
Committee and the designer of the two Italian C Class catamarans that challenged
the USA in the Little America?s Cup in the early 80?s), canted or round
boards must be forbidden as specified in the present A Class rule and for
this same reason also T-foiled rudders.
I do not think there is however need to demonstrate the advantages of canted
or round boards; proof that such boards work can be seen in the ORMA 60?
boats which have been fitted with canted boards for 10 years and now all
have round boards. The same will certainly happen to the A class if we do
nothing to prevent it, and if it does, I can assess the additional cost
for each A cat owner at around 2.000 Euros.
As founder of the CAT ?A? Italia, which was the first A class catamarans
association to be established in the world, and as long time designer and
the main builder of A class catamarans, my intention in this letter is to
denounce to the competent bodies of the ISAF, to National Authorities and
to all the ?good? IACA members the unsportsmanlike behaviour of this minority.
I believe that if nothing is done immediately to re-establish the right
rules of the game we can expect an imminent proliferation of new A cat designs
with slender hulls, solely intended to sustain the weight of the boat and
the helmsman while still or moving slowly, and fitted with inward-canted
or round boards thus allowing our beloved cat to ?take flight?.
I wonder why nobody has yet tried to stop such an evident breach of the
A class rule when other much less ?harmful? rules, such as pumping, have
been severely enforced in other classes.
At the latest IACA assembly, which was held during the 2004 A cat Worlds,
the subject was raised and heavily discussed, also as regards the presence
of five A class catamarans with inward-inclined boards.
In the end, those who sailed such catamarans, succeeded in passing an original
interpretation of the hydrofoils rule (aimed also at covering themselves
from future problems with regard to the beam rule): canted boards shall
be allowed by the class rule on condition that, when in their fully-up position,
the distance measured between the perpendiculars to the extremities of the
same boards is 2,30 m at maximum (i.e. the maximum beam in the A class).
Not surprisingly this interpretation does not prevent using the much more
promising round boards.

If we do not stop this unlawful experimentation, within a matter of months
90-95% of existing boats will become obsolete. This uncertainty creates
confusion among A class members.
On a daily basis, I am requested to fit new BIMARE A cats with long and
narrow boards not too inclined, short and wide boards very inclined, round
boards etc.
The chaos that will occur in the absence of a timely decision on this subject
is easily foreseeable.
I therefore appeal to the ISAF Multihull Committee, the A class builders,
the technicians and all the interested parties, to clarify once and for
all the hydrofoils? issue.
Sincerely
Mr. Lallo Petrucci



Appendix

The hydrofoils? effect according to the calculation of Mr Giorgio Bergamini

Test boat: 16? catamaran
Boat weight: 105 Kg
Crew weight: 120 Kg
Overall weight: 225 Kg
Boat?s speed: 6 m/s

With standard parallel daggerbords :
Immersed volume: 225 dm3
Hull drag: 215 N
Daggerboard drag: 55 N
Rudder drag: 14 N
Overall drag: 284 N

With round daggerboards (ray=1 m ? surface 0,194 m2) at heeling angle of
15°:
Immersed volume: 145 dm3 (then Lifting force 80 kg)
Daggerboard drag: 64 N
Rudder drag: 15 N
Overall drag: 227 N

With round daggerboard the overall drag is lower by 57 N or by 25% (57/227).

The conclusion of Mr Bergamini is that a boat fitted with round boards has
a 25% lower (friction plus wave) drag than the same boat fitted with standard
parallel boards, the same advantage could be achieved by lengthening the
hull by 25% (from 16 to 20 foot) or reducing the overall weight by 25% (from
225 to 180Kg).


A personal statemen of Giorgio Bergamini

Dear Lallo,

with reference to foils? issue pertaining to A class catamarans, pending
ISAF?s official ruling, I, as a member of ISAF Multihulls Committee, am
glad to offer you my technical opinion on the subject.
In brief my conclusions are:
1) the hydrofoils? effect occurs at any angle of inclination of the boards
with respect to the vertical defined by the mast;
2) if the boards are parallel or canted outwards, i.e. if respectively the
plane passing through the boards is parallel to the vertical passing through
the mast or cross it above the water level, in such a case the hydrofoils?
effect is limited, if not, in certain circumstances, negative; then such
boards are to be held allowed by the A class rule;
3) canting the mast to windward with respect to the platform has roughly
the same hydrofoils? effect as inclining the boards by the same angle inwards;
4) take this as a rough approximation, an increase of 1 degree of the inclination
of the boards with respect to the mast is equivalent to an increase of 1%
of the hull?s length, hence a proportional increase of the boat?s speed;
5) also the inclination of the board with respect to the plane passing longitudinally
along the hull or the use of asymmetrically profiled foils may make a
boat faster or better balanced as well as the asymmetry of the hulls prohibited
by the A class rule since its inception;
6) For all these reasons, in order to promote a fair competition among A
class cats and A cat sailors any inwards canted boards, i.e. any board whose
plane cross the vertical passing through the mast below the water level,
as well as any mast capable to be canted to windward, as well as any kind
of longitudinal asymmetry of the boards with respect to the axe of the hulls,
is to be held NOT permitted by the present A class rule.
Sincerely
Giorgio Bergamini