IRC YEARBOOK 2009
a single furling headsail. Except in the cases of a) that a spinnaker is not set,
significant damage or storm and heavy weather sails, b) that the HSA and LLmax dimensions do not exceed
boats claiming a rating allowance for using a single those shown on her certificate,
roller furling headsail shall use the same headsail for all c) that the pole length measured as spinnaker tack length
races in any series of races. (See rule 26.8.1) (STL) does not exceed the rated STL.
(d) except in the case of significant damage, during a d) that for a boat rated under Rule 26.3.8 a) with no
regatta run on consecutive days, including any lay spinnaker pole, the whisker pole (measured as STL) I
R
days, the sails on board shall remain the same. shall not exceed J.
(e) a spare mainsail may be on board but may not be used A second headsail may be set simultaneously.
C
as a racing replacement, either during a race or during 26.3.6 If a spinnaker can be tacked to a bowsprit in front of the

R
a regatta run on consecutive days, including any forestay, the bowsprit will be considered to be a spinnaker
U
lay days. pole and STL measured as the greater of the length of the
L
(f) sails shall be set in close proximity to the boat. longest spinnaker pole or to the extremity of the bowsprit.
E
26.1.6 (a) Adjustment or detachment of forestay and/or shrouds 26.3.7 Spare
including diagonal and jumper shrouds, or movement 26.3.8 Boats will be rated according to whether they use a

2
of the mast at the foot or the deck while racing is not spinnaker pole and/or a bowsprit according to the following
0
permitted except: configurations:
0
(i) in the case of a boat without runners, checkstays (a) No spinnaker pole (spinnaker tacked on deck) or a centre
9

or adjustable backstay when the forestay may be line bowsprit only.
adjusted but not detached. (b) An articulating bowsprit only.
(ii) in the case of Dayboats explicitly permitted by their (c) A spinnaker pole or poles either with or without a
own class rules to adjust or detach the forestay and bowsprit.
shrouds while racing. 26.4 Sailcloth
(iii)as permitted by Rule 26.1.6 (b). 26.4.1 Sailcloth containing exotic materials (at present none) will
b) A boat fitted with or carrying on board systems, to carry an additional rating tax.
adjust the forestay or the mast foot while racing
26.4.2 Sailcloth containing exotic materials shall be declared
shall declare this to the Rating Authority. Locked
on initial application for rating, revalidation, or when
conventional turnbuckles need not be declared.
amending a boat's sail inventory.
Unless the boat declares that such systems will not be
26.4.3 Only specific sails containing exotic materials which have
used while racing, the boat may then adjust the
been declared and noted on a boat's certificate may be
forestay and the mast foot vertically and/or
used while racing under IRC.
longitudinally while racing, but shall not detach
26.5 Mainsails
the forestay.
26.5.1 Where measurement bands are marked on the mast
26.2 Rig Factor
at the masthead and on the aft end of the boom, the head of
26.2.1 Rig factor (RF) is an assessment by the Rating Authority
the mainsail shall not be hoisted above the lower edge of
of the rig and sail features of the boat and their character
the band at the masthead, and the clew of the sail shall not
and efficiency when compared to a basic cruising
be pulled aft of the forward edge of the band on the boom.
configuration with substantial spars and basic rig controls.
26.5.2 Unless declared as greater under Rule 26.5.3 or lesser
26.2.2 RF above unity may be applied for: fractional, racing and
under Rule 26.5.4, mainsail seven eighth width (MUW),
lightweight rigs, high aspect ratio and efficient plan
mainsail three-quarter width (MTW), and mainsail half
forms, wing and double luff sails, specialised sail stiffening,
width (MHW) will be assumed to be 0.22*E, 0.38*E and
large headboards/cranes, permanently bent or highly
0.65*E respectively.
controllable spars, hi-tech rigging, exotic rig materials,
26.5.3 MUW measurements in excess of 0.22*E, MTW
advanced winch and deck gear arrangements, flush/
measurements in excess of 0.38*E, and MHW
efficient deck design, and any other feature which
measurements in excess of 0.65*E shall be declared.
increases sailing efficiency that is not already rated through
26.5.4 MUW measurements less than 0.22*E to a lower limit of
the rated dimensions.
0.125*E may be declared. MTW measurements less
26.2.3 RF below unity may be applied to less efficient rigs and sail
than 0.38*E to a lower limit of 0.25*E may be declared.
plans, cruising furling sails, motor sailers with large deck
MHW measurements less than 0.65*E to a lower limit of
houses, cruisers with weight/windage aloft or with basic
0.50*E may be declared.
deck gear only, or any other feature which reduces sailing
26.6 Spinnakers
efficiency that is not already rated through the rated
26.6.1 Spinnakers are rated relative to a base area appropriate
dimensions.
to a boat of the particular type and size. Any spinnaker will be
26.2.4 Full rig details shall be supplied at the time of rating
rated equitably relative to this base size.
application. The Rating Authority reserves the right to apply
26.6.2.1 Boats carrying more than three spinnakers in total on
a high rig factor until full detail is supplied.
board while racing will incur an increase in rating.
26.3 Sheeting of Sails, Sail Definitions, Bowsprits and Spinnaker Poles
26.6.2.2 An IRC Rule Authority may prescribe that for races under
26.3.1 No headsail or spinnaker may be sheeted from more than
its jurisdiction requiring compliance with ISAF Special
one point on the sail.
Regulations Category 3 or above, a boat may carry one
26.3.2 All sails shall be set and sheeted in accordance with RRS
more spinnaker than shown on her current IRC certificate
50, Setting and Sheeting Sails, with the following additions.
of area not greater than rated SPA without an increase in
26.3.3 RRS 50.3(a) is amended to the extent that a spinnaker
rating. Any such prescription shall be referenced in a
may be tacked to a bowsprit. A headsail may only be tacked
Notice of Race.
to a bowsprit if J is measured to the headsail tack
26.6.3 Spinnaker area shall be calculated from:
attachment point on the bowsprit. See the definition of J.
SPA = ((SLU + SLE)/2) * ((SF + (4 * SHW))/5) * 0.83
26.3.4 RRS 50.4 shall not apply. A spinnaker is defined as a sail
The luff (SLU) , leech (SLE), foot (SF) and half width
set forward of the foremost mast with half width (measured
(SHW) of the largest area spinnaker on board shall be
as a spinnaker) greater than 75% of foot and without
declared. The calculated area of this spinnaker will be
battens. Any other sail tacked down forward of the foremost
shown on a boat’s certificate as the maximum permitted
mast is a headsail.
spinnaker area.
26.3.5 RRS 50.3 (c) is deleted and replaced by:
26.6.4 STL is rated relative to a base length of 0.456*SPA^0.5.
A headsail may be sheeted or attached at its clew or tack to
Variations from base STL will result in variation in a boat’s
8
a spinnaker pole or whisker pole, provided:
TCC appropriate to the change in length.
41
IRC 09 Rules P33-43_bs.indd 41 1/12/08 09:10:55
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