Sigma 33 OOD Class Measurement
Rules
1. Object
These Rules, Specifications and the Approved Plans are
intended to ensure that Sigma 33 One Design Class yachts are as nearly alike as
possible as regards
i) Hull and deck shape and weight
ii) Shape and weight of keel and rudder
iii)
Shape and area of sail plan
iv) Size and weight of spars and rigging
v) Weight and distribution of accommodation layout
vi) Specification and weight of engine, stern-gear, batteries and other
machinery and other matter which may influence the speed or reduce the weight
of the yacht.
vii) The yacht and her equipment shall comply with the current Class as
interpreted by the Class Association. No Class Rule or Interpretation may
contravene the provisions of the current rating system. No alternatives are
allowed except as specified in these Rules.
2 Protection of
One Design
2.1
The administering authority for the Class shall be the
Sigma 33 OOD Class Association, which may co-operate with such National or
International Authority as will best promote the management and popularity of
the Class.
2.2
Copyrights of the Sigma 33 design shall remain the
property of David Thomas unless otherwise specifically assigned.
2.3
Sole rights to build the Sigma 33 shall remain with
Northshore Yachts Limited unless otherwise specifically assigned or licensed.
2.4
Hull, deck and rudder construction shall be of
reinforced plastics in accordance with the lines, construction and general
arrangement plans and specifications.
2.5
Production moulds for hull, deck and rudder shall be
made from GRP plugs only obtainable from the master moulds held by Northshore
Yachts Ltd. The casting pattern for the fin keel shall be taken from the master
plug held by Irons Brothers.
2.6
Hull and deck 1ay up and stiffening shall be
strictly to the specification designed to ensure similarity in shape, strength
and weight distribution.
2.7
Hull and deck shall be permanently joined, with the bull
in its mould, so that the sheerline, profile and all girths, depths and
dimensions that affect the hull shape shall be as shown on the lines plan.
2.8
In order to qualify for one design status, the yachts
shall be put in measurement trim as defined below which shall be equivalent to
the FFM (Freeboard Forward Measurement) of not more than 1094mm and FAM
(Freeboard Aft Measurement of not less than 924mm and not more than 945mm.
These measurements are taken from points where a 45-degree tangent
touches the sheerline to the surface of the water. Measurements shall be taken
on both sides of the yacht and averaged to produce the freeboard measurements.
FFM measured 634mm aft from the stem. FAM measured aft where the transom meets
the sheerline.
Measurement trim is achieved as follows:-
a) The yacht shall float upright and free of mooring or anchor effects. No
person shall be on board during measurement.
b) The yacht must be rigged ready for sailing with sheets and guys stowed aft
of the mast. The mainsail shall be furled on the boom and all remaining sails
stowed on the cabin sole aft of the mast
c) All mattresses, cushions and bedding shall be
stowed on their normal bunks and all navigational and cooking appliances shall
be in their normal stowage. Batteries, anchors and chain shall be secured in
position as described in 15.
d) No clothing food or stores shall be on board.
e) Fresh water tanks shall be empty.
f) Liferaft shall not be on board during
measurement.
Sufficient fuel shall be on board to allow the yacht to proceed under
power.
2.9
The current Approved Class Sailmaker shall be Sobstad
Sailmakers (UK) Ltd and only sails made the Class Sailmaker are permitted.
Changes in the Approved Class Sailmaker shall be authorised only by the Sigma
33 OOD Class Association which may delegate this responsibility to the
Committee.
2.10
The current Approved Class Sparmaker is Kemp Masts and
only masts, booms and spinnaker booms manufactured by the Class Sparmaker are
permitted. Changes in the Approved Class Sparmaker shall be authorised only by
the Sigma 33 OOD Class Association which may delegate this responsibility to
the Committee.
2.11
If it is considered that there has been any attempt to
depart from the One Design or these Rules in any particular, or from the spirit
of these Rules, in order to gain performance advantage, the Committee of the
Class Association has the right to invalidate the yachts Class Certificate from
the time the attempt was made until such time as any deviations have been
rectified.
3 Measurement and
Certificates
3.1
The current Measurement Authority shall be the Royal
Ocean Racing Club (RORC). Measurers shall be appointed by the Measurement
Authority. Changes in the Measurement Authority shall be authorised only by the
Sigma 33 OOD Class Association which may delegate this responsibility to the
Committee.
3.2
The Measurers shall:
i) inspect
and measure yachts under construction at the builder’s premises
ii) inspect
and measure sails
iii) inspect
and measure spars
iv) check
each boat afloat in measurement trim (Rule 2.8) (when required).
3.3
Sails and spars when inspected and found to conform to
these Rules shall be marked with the measurer’s official stamp; only those so
marked shall be used.
3.4
i) On application by the owner and after payment of the
due fees to the Measurement Authority, the Measurement Authority having
received satisfactory reports from the measurer(s), shall issue a One-Design
Rating Certificate for the One-Design Rating currently applicable to the Sigma
33 Class and stating that the yacht complies with
these Rules.
ii) Such certificates shall remain valid until
December 31 in the year of issue of the certificate or change of ownership
whichever first occurs.
iii)
Certificates may be revalidated for a further year (or until change of
ownership) on receipt from the owner of a certificate that all sails and spars
are duly marked and that no alterations have been made to the boat.
iv) The Class Association may require a boat to
be checked in measurement trim during any One Design event.
v) On
change of ownership, a boat shall be inspected by a Measurer and checked afloat
in measurement trim before issue of a certificate to the new owner.
3 5 The fees payable in
connection with measurement and certification shall be agreed from time to time
by the Committee of the Association with the Measurement Authority.
4 Hull and
Deck (Including Cockpit)
4.1 The hull and deck
construction shall be in accordance with the Approved Plan and Specification.
4.2 The Datum Weight of the yacht, as
defined in 4.3 shall be 4150/4350 kg.
4.3 The Datum Weight shall be the weight
of the yacht as it leaves the Builder’s works included all fitted and loose
equipment, spars and 22.5 litres of fuel but excluding sails and with water
tanks empty.
4.4 The cockpit grating must not be
removed and must be kept in place while racing.
4.5 The removal of moulding marks and
blemishes from the hull is permitted provided that the hull is not in any way
altered so as to depart from the original shape. Repairs to the hull shall be
made so as to return the affected areas to the original shape. Extensive
repairs to a yacht must be reported to the Class Association which may require
the yacht to be re-measured. The hull below the waterline including keel and
rudder may be covered in protective coatings which must not affect the original
shape of these areas.
4.6 All surfaces of the hull below the
waterline including keel and rudder must be coated in antifouling paint at all
times whilst racing. The antifouling paint shall be kept in good repair so that
bare patches are not allowed to develop.
5 Keel Casting
5.1 The fin keel shall be of cast iron, manufactured according to the
Master Plug and Mould, bolted in position as shown in the Lines Plan
5.2 The weight of the fin keel casting
shall be 1505/1575kg.
5.3 The removal of foundry blemishes is
permitted but the keel shall not be ground, built up or in any way altered so
that it departs from standard shape. The keel may be covered with preservative
coatings and antifouling. Measurement templates may be applied to the keel to
ensure compliance with standards.
6 Rudder
6.1 The rudder blade shall be of GRP made
from moulds taken from the Master Plug.
6.2 The rudder stock shall be made from
solid stainless steel rod not less than 45mm diameter.
6.3 The design and construction of tiller
and tiller extension is optional. Wheel steering is not permitted.
6.4 The removal of moulding marks and
blemishes from the rudder is permitted provided that the rudder profile or
section is not in any way altered so as to depart from the standard shape.
Measurement
templates may be applied to ensure compliance with this Rule.
6.5 The minimum weight of the rudder and
stock shall not be less than 40kg.
7 Mast
7.1 The mast shall be of 90% aluminium
alloy extrusion with integral full groove. The mast shall be made from constant
section extrusion with no tapering allowed.
7.2 The sectional weight of the mast
shall be not less than 4.71 kg/metre.
7.3 Sectional dimensions of the mast
shall be 107/117mm athwartships and 136/156 fore and aft including the luff
groove.
7.4 The forestay will attach to the
forestay plate moulded into the hull in such a way that the horizontal distance
between the forestay pin and the forward face of the hull moulding is
237/257mm.
7.5 The straight line distance between
the forestay pin and the forward surface of the mast extrusion at its lowest
point shall be 3624/3644 mm.
7.6 Bands of contrasting colour shall he
painted on the mast as follows:
i) with
its upper edge 985/1005 mm above the mast plinth in the deck moulding on which
the mast step is fastened.
ii) with
its lower edge 11570/11590 mm above the upper edge of the band defined in (i).
7.7 No alterations to the mast are
permitted except for approved electronic devices, navigation lights, wind
vanes, pre-feeders and like additions. No alterations to the main or genoa
halyard exits are permitted, nor any alteration which may change the moment of
inertia of the spar. The spinnaker halyard may exit from the port side of the
mast. A slot may be cut with its centre point 2380/2420 mm above the bottom of
the mast extrusion and its forward edge 25/35 mm forward of the jigging groove
on the side of the mast. If this slot is cut a standard Kemp Masts slot plate
shall be fitted but no other jamming or cleating devices shall be fitted to the
mast.
7.8 A steaming light as originally
supplied or similar shall be fitted to the forward face of the mast in
accordance with IRPCS.
8 Mast Rigging
8.1
A combined chainplate fitting shall be attached port and
starboard. The upper shrouds shall be attached by a rigging screw to the aft
pin and the lower shrouds by a rigging screw to the forward pin. The forestay
shall be attached by a rigging screw to the forestay chainplate.
8.2
The forestay and shrouds shall be of 1 x 19 stainless
steel wire rope of not less than 7 mm diameter. The wire strands shall be of
round section, each strand being of the same diameter. Alternatively Dyform material of the same
dimensions may be used.
8.3
The forestay shall be attached to the mast so that the
centreline of the wire would intersect the foreside of the mast at a point not
more than 9914 mm above the band as defined in 7.6 (1).
8.4
Any forestay luff foil is permitted which the Committee
authorises under these Rules and which will not affect the Standard Rating. In
particular, any forestay luff foil is permitted which measures not more than 35
mm at right angles to its longitudinal axis. The forestay, Rule 8.2, must bear
the forestay loads.
8.5
The upper shrouds shall be attached to the mast so that
the centreline of the wire would intersect the side of the mast 9487/9511 mm
above the band defined in 7.6 (i).
8.6
The lower shrouds shall he attached to the mast so that
the centreline of the wire would intersect the side of the mast at a point
4157/4181mm above the band defined in 7.6 (i)
8.7
One topmast backstay of not less than 5mm 1 x 19
stainless steel wire rope shall be attached to the masthead and to a lever
tensioning system at the transom.
8.8
The spreaders shall be of fixed type angled aft 22.5
degrees to the athwartships plane of the mast and attached at a point 4427/4451
mm above the band as defined in 7.6 (i). The distance between shrouds at the
spreader ends shall be 1985/2015 mm.
8.9
The spinnaker shall not be hoisted higher than the
forestay intersection point as defined in 8.3. Only one synthetic rope
spinnaker halyard shall befitted.
8.10
Two jib halyards are permitted, which may be of wire or
synthetic rope, and each shall intersect the mast below the forestay
intersection point as defined in 8.3.
8.11
Tension in the rigging may only be adjusted by means of
the rigging screws on shrouds and forestay. Running backstays are prohibited.
8.12
In order to vary the basic mast rake and/or prebend, the
backstay lower strop attached to the shorter arm of the lever system may be
replaced by an alternative strop of equivalent strength and construction (5 mm
1 x 19). The maximum length of this strop shall not exceed 780 mm. The backstay
upper span shall not be altered from the specified 3300mm in length.
Pre-race tuning may be achieved
by using the rigging screw provided at the base of the main backstay wire.
Whilst racing, top mast backstay adjustment shall only be achieved by manual
adjustment of a rope purchase or tackle driving the long arm of the standard
Kemp Masts backstay lever as originally supplied.
The lower strop and purchase
system shall be secured separately to an eye bolt on each side of the upper face
of the transom.
Purchase systems may be of any
power ratio and may be double ended. Maximum straight line shortening distance
of the topmast backstay system shall not exceed 110 mm measured between the
lower terminals of the single part upper stay and the centre of the upper face
of the rudder post.
9 Main Boom
9.1
The main boom shall be of 90% aluminium alloy constant
section extrusion incorporating an integral mainsail foot groove.
9.2
Sectional dimensions shall be 123/133 mm in depth
including foot groove and 85/95 mm in width. Sectional weight shall be not less
than 2.79 kg/metre.
9.3
A band of contrasting colour shall be painted on the
boom with its forward edge not more than 3935 mm from the after face of the
mast extrusion.
9.4 Tapered booms and lightening holes
are prohibited.
9.5 The main boom shall be
equipped with two reefing lines and flattening reef outhaul.
9.6 Roller reefing systems are
not permitted.
10
Spinnaker Boom
10.1
No part of the spinnaker boom including fittings shall
be capable of extending more than 3580 mm at right angles from the centreline
of the mast when the spinnaker boom is attached to the mast.
10.2
The point of attachment for the spinnaker pole to the
mast shall be not more than 1369 mm above the band defined in 7.6 (i).
10.3
Only one aluminium
alloy spinnaker boom shall be used. Reaching struts are prohibited.
10.4
The
forward end of the spinnaker pole, when stowed, shall not be shaft the after
end of the anchor well.
10.5
The
spinnaker pole shall be the standard extrusion supplied by the Approved Class
Sparmaker with end fittings as originally or currently supplied. Upward opening
trigger latch type fittings are not permitted.
11 Sails
11.1
The sails shall be measured in accordance with the
current rating rule.
11.2
The number of sails that shall be carried is one each of
the following: mainsail, 150% genoa, 135% genoa, working jib, storm jib, light
spinnaker, heavy spinnaker. If an owner wishes to cruise after the finish of an
offshore race, he may carry old fore and aft sails for this purpose provided that they are not used during the
race.
11.3
Where applicable these sails shall have dimensions and
shall be set in a manner which does not incur penalties under the current Class
rating rule.
11.4
All sails shall be of woven material except the mainsail
and the 150% and 135% genoas, which may be constructed as a laminate to the
patented Genesis system. Dimensions in metres are the same for both forms of
construction.
Minimum cloth weights are given for woven
sails. Film and thread specifications are given for Genesis sails.
Genesis Construction
Base Film: Genesis prelaminate. Lamination: 2 x 0.012 nun PET. Seam Size:
50 mm
2 x 400 x 400 Denier polyester scrim.
Thread Type and Denier: 1800 Denier polyester laid by computer — 1 x
thread per cm. Seam Construction: Bonded epoxy thread to thread with scrim
insert.
Corner reinforcement: P.E.T. 0.05 mm with load orientated fibres bonded by heat
and pressure set polyester adhesive.
Sail |
Luff |
Leech |
Foot |
Min cloth weight (U.S. oz.) |
|||
|
Max. |
Min. |
Max. |
Min |
Max. |
Min. |
(Dacron
Sails only) |
Mainsail |
11.95 |
- |
12.35 |
- |
3.935 |
- |
8.0 |
|
(Three
reefs shall be fitted parallel to the foot at 1.12m, 2.52m and 4.80m from
centre of tack cringle) |
||||||
150% genoa |
11.20 |
11.10 |
10.80 |
10.70 |
5.60 |
5.5 |
5.5 |
|
(Longest
perpendicular luff to clew max, 5.31, min 5.21) |
||||||
135% genoa |
10.52 |
10.42 |
9.76 |
9.66 |
4.88 |
4.78 |
6.5 |
Working jib |
9.60 |
9.50 |
8.08 |
7.98 |
3.66 |
3.56 |
6.5 |
|
Luff length |
Width |
Min cloth weight (U.S. oz.) |
||
|
Max. |
Min. |
Max. |
Min. |
|
Light spinnaker |
11.20 |
11.10 |
6.44 |
6.35 |
0.8 |
Heavy spinnaker |
11.10 |
10.90 |
5.90 |
5.80 |
1.5 |
11.5
The mainsail mid-girth measurement (MOM) shall not
exceed 2590mm and the upper girth measurement (MGU) shall not exceed 1540 mm,
measured in accordance with the current rating rule.
11.6
The mainsail shall have four battens. The upper batten
may be full length and the other three battens shall not exceed 1300 mm.
11.7
The mainsail headboard width shall not exceed 152 mm.
11.8
The mainsail may be fitted with luff and leech
Cunningham holes and may have a soft foot’ with cloth lighter than 8.0 oz on
the shell
11.9
The mainsail may only be set within the dimensions
governed by the bands specified in 7.6 (in), 7.6 (ii) and 9.3.
11.10 Loose
footed mainsails are permitted.
11.11 The
150% genoa and/or the main may have a window or windows not exceeding a
combined total area of 1.5 sqm.
11.12 The
135% genoa may have one reef with the luff cringle 765 mm/665 mm from the tack
cringle and the leech cringle 1140 mm/1040 mm from the clew cringle.
11.13 Only
sails made by the Approved Class Sailmaker and carrying the measurement stamp
of the Measurement Authority are permitted. Sails may not be re-cut or altered
in any particular except by the Approved Class Sailmaker. Repairs maybe
undertaken by anyone provided that they do not affect the shape or size of any
sail in any way.
11.14 The
Sigma symbol in red shall be affixed to both sides of the mainsail above the
sail numbers and shall be of a height of 600 mm/620 mm.
11.15 Changes
to sail wardrobe. Any proposed change to the number of sails as defined in 11.2
or the design of sails as defined in 11.4 shall not be implemented until 21
calendar months have elapsed following notification that the Committee is
investigating the proposal. Small changes in the construction of the sails may
be introduced as the Committee sees fit but not less than six months notice.
12 Deck Gear
12.1
Yachts shall carry two halyard winches (two speed); two
primary sheet winches (two speed) on the cockpit winch turrets; two secondary
sheet winches (two speed); and one reefing winch on the mast and sited below
the main boom. All winches are to be of the size and power equivalent to those
originally specified. Self-tailing devices are permitted.
12.2
Single genoa sheeting tracks shall be permanently fixed
to the side decks, port and starboard, adjacent to the coachroof. Four genoa
sheet fairleads may be fitted (two per side). Ball bearing or roller-bearing
genoa fairleads, on these tracks, are not permitted. Headsails and spinnakers
may be sheeted to the aluminium toe rails.
12.3
Yachts shall be fitted with bow and Stem pulpits of
stainless steel, and eight stanchions with double lifelines in compliance with
ORC special regulations currently in force.
12.4
A mainsheet track shall be fitted to the inset plinth in
the cockpit seats. The track shall be straight and shall fit between the
cockpit walls. Packing is permitted under the track and its mountings. The
packing shall not exceed 30 mm in thickness.
12.5
The removable bridge deck moulding shall always be
secured in place during races which necessitate the carrying of a liferaft. In
all other races, the removable bridge deck must be on board but not necessarily
secured in place.
12.6
Mainsheet, traveller, kicking strap or vang are
optional. Hydraulic, electric or pneumatic actuators are prohibited.
12.7
The arrangements of halyards, sheets, guys and control
lines, their turning blocks and cleats are optional within the provisions of
these Rules.
13 Interior Accommodation
13.1 The builder shall stall times maintain
close tolerances on position, size and weight of materials used in interior
bulkheads, joinery work, cabin sole and lining in an endeavour to produce yachts of the closest weight and strength
tolerances within these Rules. The Class Association shall be kept informed of
any proposed change in the specification that might affect the weight or weight
distribution of the yacht.
13.2
All yachts shall have complete interior structure in way
of forecabin, saloon, galley, cooker as originally fitted or of equivalent
weight having two hob burners, grill and oven, gas bottle or bottles of total
weight not less than 12 lb, chart table, WC toilet compartment and saloon table
in the original fixed position. No lightening holes shall be cut or drilled.
13.3
All yachts shall carry a full set of berth mattresses of
minimum thickness 100 mm on their appropriate berths. The half berth mattress
to complete the double berth must always be on board, but it does not have to
be on the double berth. Between October 1 and April 30 Area fleets when racing
in One Design only may request that the Sailing Instructions for the Winter and
Spring Series should specify that this rule is suspended.
13.4
All yachts shall have completed head, topside and
coachroof linings as fitted by the builders.
13.5 Two fresh water storage tanks of minimum
capacity 180 litres (approx. 40 galls) shall be installed beneath the after
ends of the main saloon berths.
14 Engine
and Stern Gear
14.1
The engine model and location shall be agreed from time
to time by the Class Association and Designer. Its weight and weight
distribution (whether by using corrector weights or not) shall not change from
those of the Volvo Penta MD7A marine diesel engine of minimum weight 166 kg
originally fitted.
14.2
A propeller and stern gear shall befitted as in the
Approved Plan. The minimum propeller diameter shall be 380mm, minimum blade
width 90mm and projected propeller hub diameter shall not be less than 60 mm.
14.3
The Class Association shall be kept informed of any
proposed change in engine specification that might affect weight, position or
stern gear dimensions.
14.4
A rigid fuel tank
of minimum capacity 68 litres (approx. 15 galls) shall be fitted.
15 Other Equipment
15.1
Two anchors, one with a minimum weight of 25 lb (11.34
Kg), and one with a minimum weight of 15 lb (6.80 Kg) and two fathoms (3.66m of
5/16” (8mm) chain shall be carried. Both anchors and the chain shall be carried
in a marked stowage not more than 2750 mm from the stem.
15.2
Navigation,
emergency, safety and general equipment shall be carried on board the yacht to
the specification of the Sailing Instructions and the applicable Category of
the Offshore Racing Council Special Regulations governing minimum equipment
currently in force. Copies of the booklet
containing these Regulations are available from the Offshore Racing Council, 19
St. James Place, London, SWIA 1NN.
15.3
Two batteries each weighing a minimum of 29 kg shall be
carried in the battery compartment aft of the main saloon bulkhead.
15.4
There is no restriction on radio or electronic aids but
automatic, mechanical and wind vane devices for steering must not be used
within racing unless specifically permitted in the Notice of Race or Sailing
Instructions.
15.5
Minor
modifications to enhance the safety and comfort of the yacht are permitted,
subject to approval of the Class Association.
16 One
Design Racing
16.1
As a condition for the granting of a One-Design Rating,
the Officers and Committee have given an undertaking that all yachts of the
Class shall adopt it and that any yacht claiming an individual rating shall be
excluded from racing as a one-design in the Class. It shall be mandatory of the
Committee to exclude from all Sigma 33 Class racing any yacht claiming an
individual rating.
16.2
When racing in CHS, the Class crew limit is seven
persons. Unless otherwise specified in the sailing instructions, when racing
One Design, one additional crew member under the age of fourteen may be carried.
When racing in IMS in addition to the limit of seven persons, the crew weight shall not exceed that appearing on the
yacht’s IMS certificate.