Author makes every effort to ensure the accuracy of these
rules but does not accept responsibility for inaccuracy.To
ensure accuuracy please consult the class association.
Index to Rules
||2.0 Protection Of the One Design
||3.0 Measurement and certificates
|4.0 Hull and Deck (including cockpit)
||5.0 Keel Casting
||8.0 Mast Rigging
||9.0 Main Boom
|10.0 Spinnaker Boom
||12.0 Deck Gear
|13.0 Interior Accomadation
||14.0 Engine and Stern Gear
||15.0 Other Equipment
||17.0 Exotic Materials
|19.0 Crew Qualifications
These rules, Specifications and the
Approved Plans are intended to ensure that Sigma 38 One-Design
Class yachts are as nearly alike as possible as regards.
- Hull and deck
shape and weight.
- Shape and weight
of keel and rudder.
- Shape and area of
- Size and weight
of spars and rigging.
- Weight and
distribution of accommodation layout.
- Specification and
weight of engine, sterngear, batteries and other
- Any other matter
which may influence the speed or affect the
weight of the yacht.
The yacht and her
equipment shall comply with the current Class Rules as
interpreted by the Class Association. No alternatives are
allowed except as specified in these Rules. If in doubt
as to whether a particular system or alteration is
permitted, clarification should be obtained before
becoming committed to any expense.
|2.0 Protection of the One Design
2.0 Protection of the One-Design
2.1 The administering
authority for the Class shall be the Sigma 38 OOD Class
Associationwith such National or International Authority
as will best promote the , which may co-operate
management and popularity of the Class.
2.2 Copyrights of the Sigma 38 design shall remain the
property of the Designer David Thomas unless otherwise
2.3 Rights to build the Sigma 38 shall remain with Marine
Project (Plymouth) Ltd. and Northshore Yachts Ltd.,
referred to as the Builders, 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
2.5 Production moulds for hull, deck and rudder shall be
made from GRP plugs only obtainable from the Master
Moulds. The casting pattern for the fin keel shall be
taken from the master plug.
2.6 Hull and deck and internal stiffener layup shall be
strictly to the specification designed to ensure
similarity in shape, strength and weight distribution.
2.7 The internal stiffening module shall be permanently
joined with the hull in the building mould.
The sheerline and profile shall be as shown on the lines
plan and all girths, depths and dimensions that affect
the hull shape shall be as defined by IMS standard hull
2.8 In order to qualify for one design status the yachts
shall be put in measurement trim as defined below. FFM (Freeboard
Forward Measurement) shall be not more than 1.305m and
FAM (Freeboard Aft Measurement) shall be not less than 0.965m
and not more than 0.980m. 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 is measured 592mm
aft from the stem. FAM is measured where the transom
meets the sheerline. Measurement trim is achieved as
a) The yacht shall float upright and free of mooring or
anchor effects. No person shall be on board.
b) The yacht must be rigged ready for sailing with sheets
and guys stowed aft of the mast. No sails shall be on
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) Life raft shall not be on board.
g) Fuel tank shall be full.
2.9 The Approved Class Spar makers shall be Kemp Masts
2.10 Sails for Class racing shall only be manufactured by
sailmakers approved by the Association, and to the design
and specification approved by the Class 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 yacht's Class
Certificate from the time the attempt was made until such
time as any deviations have been rectified.
2.12 A Builder's Plaque shall be fixed in an approved
i) Hull number
ii) Yard number
iii) Keel weight
iv) Datum weight
|3.0 Measurement and Certificates
3.0 Measurement and Certificates
3.1 The Measurement Authority shall be the Owner's
National Authority. Class Measurers shall be appointed by
the National Measurement Authority.
3.2 The Measurers shall:
i) Inspect and measure yachts under construction at the
ii) Inspect and measure sails.
iii) Check each boat afloat in measurement trim (Rule 2.8).
3.3 Sails and spars when inspected and found to conform
to these Rules shall be marked with the measurers stamp;
only those so marked shall be used.
3.4 i) All yachts competing in Class or Handicap racing
as a Sigma 38 OOD shall hold a current, valid Class
Certificate. On application by the owner and after
receipt of the due fees and satisfactory reports from the
measurer(s), the National Measurement Authority will
issue a Valid Class Certificate for the IRC and Rating
currently applicable to the Sigma 38 Class, stating that
the yacht complies with these Rules.
ii) Such certificates shall remain valid until the 31st
December in the year of issue of the certificate or
change or ownership, whichever first occurs.
iii) Certificates may be revalidated for a further year (or
until change of ownership) on receipt by the Class
Secretary from the owner of a certificate that all sails
and spars are duly marked and that no alterations have
been made to the yacht.
iv) The Class Association may require a yacht to be
checked in measurement trim during any One Design event.
v) On change of ownership, a yacht shall be inspected by
a Class 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 National
|4.0 hull and Deck (including
4.0 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 6580 +/- 130kg. This shall be recorded on the
Builder's Plaque as in para 2.12. Corrector weights shall
be added if necessary, half forward of the main bulkhead
and half aft of the engine, and shall not be removed
during the life of the boat.
4.3 Datum Weight shall be the weight of the yacht as it
leaves the Builder's works including all fitted and loose
equipment and 5 galls. of fuel but excluding spars, sails
and with water tanks empty.
4.4 The removal of molding marks and blemishes from the
hull is permitted provided that the hull is not in any
way altered so as to depart from the standard shape. The
hull may be covered with protective coatings and shall be
anti-fouled. Repairs shall return the affected area to
the standard shape. Extensive repairs to the yacht shall
be reported to the Class Association which may require
the yacht to be remeasured.
|5.0 Keel Casting
5.0 Keel Casting
5.1 The fin keel shall be of cast iron and lead,
manufactured according to the Master Plug and Mould and
conforming to the Class Template, bolted in position as
shown in the Lines Plan.
5.2 The weight of the combined fin keel casting shall be
2640 +/- 40kg. The keel weight shall be recorded on the
5.3 The keel shall not be ground except to remove minor
casting blemishes and in particular no part of the
trailing edge may be less than 10mm. Filler may be used
to fair the keel so long as the keel profile is not
altered from standard. The keel may be covered with
preservative coatings and shall be anti-fouled.
6.1 The rudder blade shall be of GRP made from moulds
taken from the Master Plug.
6.2 The rubber stock shall be made from solid stainless
steel rod not less than 63mm (2½ in.) diameter.
6.3 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.
6.4 The rudder may be covered with preservative coatings
and shall be anti-fouled.
7.1 The mast shall be of 90% aluminum alloy extrusion
with integral luff groove.
7.2 The basic sectional weight of the mast shall be not
less than 5.73kg/metre.
7.3 Section dimensions of the mast shall be 127/137mm
athwartships and 179/199mm fore and aft including the
luff groove. The top mast shall be tapered over not more
than 2700mm from the masthead and the minimum section
dimension of the masthead shall be 120mm x 90mm.
7.4 The straight line distance between the forestay pin
and the centre of the mast ring shall be 4067 +/- 10mm.
7.5 Bands of contrasting colour shall be painted on the
mast as follows:
i) With its upper edge not more than 3010mm or less than
2900mm above the underside of the "T" Base on
which the mast step is fastened.
ii) With its lower edge not more than 14478mm above the
upper edge of the band defined in (i).
7.6 No alterations to the mast are permitted except for
navigation lights, wind vanes, pre-feeders, jamming cleat
for uphaul and similar additions. No alterations to
Halyard exits are permitted nor any alteration which
might change the moment of inertia of the spar.
|8.0 Mast Rigging
8.0 Mast Rigging
8.1 Combined chain plate fittings shall be attached port
and starboard. The upper shrouds shall be attached by a
rigging screw to the forward pins. The intermediate
shrouds shall be attached by a rigging screw to the aft
pins and the lower shrouds by a rigging screw to the
inner pins. The forestay chain plate.
8.2 All standing rigging shall be of 1 x 19 stainless
steel wire rope. The wire strands shall be of round
section, each strand being of the same diameter. The caps
and lower shrouds shall be not less than 10mm diameter,
the forestay not less than 9mm diameter and the
intermediated shrouds not less than 8mm diameter.
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 14900mm above the
underside of the "T" base in 7.5(i). The
maximum forestay length shall not exceed 13865mm.
8.4 One topmast backstay of not less than 8mm shall be
attached to the masthead and to a hydraulic tensioning
system at the transom with 200mm maximum adjustment. No
additional system or device is permitted for adjusting
the topmast backstay.
8.5 The spreaders shall be of fixed type angled aft 25
degree to the athwartships plane of the mast and attached
at points 10673/10713mm and 6423/6493mm above the
underside of the "T" base in 7.5(i).
8.6 The spinnaker shall not be hoisted higher than the
forestay intersection point as defined in 8.3. Only two
spinnaker halyards shall be fitted.
8.7 One jib halyard is permitted and shall intersect the
mast below the forestay intersection point as defined in
8.8 Two Running Backstays of not less than 7mm 1 x 19
SSWR with single sheave block attached, providing a 2:1
purchase, may be fitted. These backstays shall be
anchored to the eye bolts fitted in the toe rails. The
running backstay tails may only be taken to the aft pair
of Lewmar 40c winches for tensioning.
8.9 All halyards may be either of flexible steel wire of
minimum diameter 6mm for the main halyard and 5mm for
others, with polyester tails of minimum diameter 12mm, or
Spectra/Dyneema rope of minimum diameter 10mm for the
main halyard and 8mm for the others. The outer cover,
which shall be of polyester, may be removed for a maximum
length of 2m at each end of the halyard.
|9.0 Main Boom
9.0 Main Boom
9.1 The main boom shall be of 90% aluminum alloy constant
section extrusion incorporating an integral mainsail foot
9.2 Sectional dimensions shall be max. 205mm in depth
including luff groove and max. 130mm in width. Sectional
weight shall be not less than 4.4kg/metre.
9.3 A band of contrasting colour shall be painted on the
boom with its forward edge not more than 5182mm from the
after face of the mast extrusion.
9.4 Tapered booms and lighting holes are prohibited.
9.5 The main boom shall be equipped for triple slab
reefing and outhaul.
9.6 Roller reefing systems are not permitted.
9.7 A Kemp rod kicker shall be fitted. This shall be
either the standard version or the gas lift upgrade.
|10.0 Spinnaker Boom
10.0 Spinnaker Boom
10.1 No part of the spinnaker boom including fittings
shall be capable of extending more than 3980mm at right
angles from the centreline of the mast when the spinnaker
boom is attached to the mast.
10.2 The point of attachment of the spinnaker pole to the
mast shall be not more than 4600mm above the underside of
the "T" base in 7.5(i).
10.3 Only one aluminum alloy spinnaker boom shall be used.
Reaching structs are prohibited.
10.4 The spinnaker pole shall be stowed on deck, forward
of the mast when racing. It may be left attached to the
11.1 The sails shall be constructed and measured in
accordance with the current ISAF Sail Measurement Rules.
11.2 The number of sails that shall be carried is one of
each of the following: mainsail, 135% Genoa, No 2 Genoa,
working jib, light spinnaker, heavy spinnaker. If so
required by the Sailing Instructions, a storm jib,
trisail and other additional storm sails may be carried.
11.3 If an owner wishes to cruise after the finish of an
offshore race, he may carry extra fore and aft sails for
this purpose provided that they are not used during the
race. Each such sail shall be marked on both sides at the
head with 300mm diameter red disc marking.
11.4 The dimensions (in metres) and minimum cloth weight
(in U.S. oz) are as follows:
LONGEST PERPENDICULAR LUFF TO CLEW 5.34
HALF GIRTH 3.21
THREE QUARTER GRITH 1.85
The mainsail shall be manufactured either from
conventional Dacron, Genesis system (USA patent nos. 4,708080)
or such other material approved by the Class Association.
The Dacron main shall have minimum cloth weight 8.0oz and
cross cut construction. An additional ply on the leech
over the reef area, and from the head to below the top
batten is permitted. Corners may be radial construction.
The sail shall have a minimum weight, excluding battens,
Three reefs shall be fitted parallel to the foot at 1.37m,
3.35m and 5.91m from centre of tack cringle.
The 135% Genoa and No.2 Genoa may be either Dacron or
Polyester film material, including Mylar and Genesis or
such other material approved by the Class Association.
The maximum recommended wind speed shall be clearly
marked on the clew of the 135% Genoa, and shall not be
less than 25 knots apparent. The Working Jib shall be
Dacron, minimum weight 8.0oz. The No. 2 Genoa may have a
maximum of three leech battens, none of which shall
exceed 900mm in length.
135% Genoa No. 2 Genoa Working Jib
MAX. MIN MAX. MIN. MAX. MIN.
LUFF 13.25 13.15 13.15 13.05 11.40 11.30
LEECH 12.40 12.30 12.02 11.92 9.80 9.70
FOOT 5.90 5.80 4.32 4.22 3.87 3.77
LP 5.34 5.24 4.00 3.90 3.18 3.08
LUFF 13.20 13.20
MAX. WIDTH 7.13 7.13
Spinnakers shall be made of Nylon and have a maximum
cloth weight of Light 0.8oz, Heavy 1.5oz. The heavy
spinnaker shall have a maximum upper girth measurement of
4.05 metres at a point 3 metres from the head.
11.5 The mainsail shall have four battens. The upper
batten shall not exceed 980mm, the two middle battens
1760mm and the lower batten 1290mm.
11.6 The mailsail headboard width shall not exceed 200mm
and the batten Leech Penalty distance shall not be less
11.7 The mainsail may be fitted with luff and leech
Cunningham holes and may have a "soft foot"
with lighter cloth, or a loose foot.
11.8 The mainsail may only be set within the dimensions
governed by the bands specified in 7.5 and 9.3.
11.9 Loose footed mainsails are permitted.
11.10 The 135% genoa and/or the main may have a window or
windows not exceeding a combined total of 0.2sq.m.
11.11 The standard Forestay shall be used with the Kemp
Furlex systems or Tuff Luff. The forestay shall bear the
11.12 Only sails made be the Approved Class Sailmakers
and carrying the measurement stamp of the Class
Measurement Authority including the date and signature of
the measurers are permitted, save that storm jibs and
trisails may be made by any sailmaker provided that they
comply with the provisions of the ORC Special Regulations
10.21 to 10.23 (1995).
11.13 Only sails made by the Sailmakers approved by the
Class Association and carrying the measurement stamp of
the Class Measurement Authority including the date and
signature of the measurer are permitted, save that storm
jibs and trysails may be made by any sailmaker provided
that the comply with they provisions of the ORC Special
Regulations 10.21 to 10.23 (1995).
11.14 The Sigma symbol in red with two stripes shall be
affixed to both sides of the mainsail above the National
11.15 Sail specification may be updated when and if this
is considered beneficial to the Class but not more
frequently than once every two years and with the
approval of the Class Association.
|12.0 Deck Gear
12.0 Deck Gear
12.1 Yachts shall carry two halyard winches (Lewmar 40C);
two primary sheet winches (Lewmer 52C or 50C) on the
cockpit winch turrets; two secondary sheet runner winches
(Lewmer 40C); and one reefing winch (Lewmer 30C) on the
mast and sited below the main boom. Self-tailing versions
are permitted. Where reefing lines are led aft to the
cockpit, the reefing winch may be removed from the mast:
detachable blocks may be fitted at the bottom of the mast
for this purpose. No additional cleats or jammers may be
fitted, and although the cockpit winches may be used, in
order to free them of other use, only the existing
jammers on the boom are available.
12.2 Genoa sheeting tracks shall be permanently fixed to
the side decks, port and starboard, adjacent to the
coachroof and forward on the top of the coachroof. These
tracks shall remain as fitted by the Builders. Six genoa
sheet fairleads may be fitted (3 per side). Headsails and
Spinnakers may be sheeted to the aluminum toe rails. A
device may be fitted to permit fore and aft adjustment of
the deckside genoa sheet fairleads while under load. For
this purpose, turning blocks and one set of jamming
cleats may be fitted to each side of the deck/coachroof,
and alternative genoa sheet fairleads may be fitted.
12.3 Bow and stern pulpits and eight stanchions with
double lifelines, shall be fitted in compliance with ORC
Special Regulations currently in force
12.4 A mainsheet track of maximum length 1320mm between
stops shall be fitted to the plinth on the cockpit seats.
Only the track either originally or currently fitted by
the Builders is permitted. An alternative traveller
system is permitted including the use of extra purchase,
provided it runs on the existing track as fitted by the
12.5 Hydraulic, electric or pneumatic actuators are
prohibited except as provided for the topmost backstay
and the rod kicker. An alternative mainsheet system may
be fitted, and this may include provision for coarse and
fine tuning. Where an alternative system is fitted, which
does not require the use of mainsheet winch, this may be
12.6 All turning blocks, jammers and cleats shall remain
as originally fitted by the Builder, or as the current
building specification, except as provided in these Rules.
Any option listed by Sigma Yachts or Northshore Yachts
Ltd. as standard may be carried. This includes the
fitting or removal of Furlex roller reefing equipment,
including the necessary blocks and cleats.
12.7 Where self-tailing winches are used, the
corresponding jamming cleats may be removed.
12.8 A double-ended kicker may be fitted in replacement
of the existing system and one set of jamming cleats may
be fitted to each side of the deck for this purpose.
12.9 Detachable blocks, including snatchblocks, and also
handybillies may be fitted to the toe-rail and to the
bottom of the mast; these may be used for barber hauling,
fixing a preventer, or leading lines aft from the mast,
and in the event of gear failure.
12.10 Any make of block may be used to replace existing
loose or shackled on blocks except that no blocks or
fittings on the yacht may be made of or contain titanium.
12.11 Sheets, guys, reefing lines and other control lines
may be made of any material.
|13.0 interior Accomodation
13.0 Interior Accommodation
13.1 The builder shall at all times maintain close
tolerances on position, size and weight of materials used
in interior bulkheads, joinery work, cabin sole and
lining in an endevour to produce yachts of the closest
weight and strength tolerances within these Rules.
The Class Association shall keep 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, aft cabin, saloon, gallery, cooker as
originally fitted, gas bottles of total weight not less
than 5.44KG (12lb), chart table, 1 WC toilet compartment.
No lightening holes shall be cut or drilled.
13.3 All yachts shall carry a full set of berth matresses
of minimum thickness 100mm on the appropriate berths.
13.4 All yachts shall have complete head, topside and
coachroof lining and trim mouldings as fitted by the
Two fresh water storage tanks of total capacity not
exceeding 332 litres (approx. 60 galls) shall be
installed beneath the after ends of the main saloon
|14.0 Engine and Stern Gear
14.0 Engine and Stern Gear
14.1 The standard engine model and location shall be the
Volvo Penta 2003R or the MD 2030 installed as shown on
the Official plans. The Turbo version of the Volvo 2003
engine may be installed at the option of the owner. The
Class Engine Weight is 159kg. If the MD 2030 engine is
fitted, a corrector weight of 7kg shall be added to the
14.2 A folding propeller and stern gear shall be fitted
by the Builders to the Approved Plan.
14.3 The Class Association shall keep informed of any
proposed change in engine specification that might affect
weight, position or stern dimensions.
14.4 A fuel tank of minimum capacity 114 litres (approx.
25 galls) shall be fitted.
|15.0 Other Equipment
15.0 Other Equipment
15.1 A minimum of one 16kg (35lb) anchor, one 9kg (20lb)
anchor and 7300mm of 8mm chain shall be carried. One
anchor and the chain shall be carried in the forward
anchor well. The other anchor shall be carried in the
marked stowage, not more than 300mm from the stem and
forward of the forward bulkhead.
15.2 Navigation, emergency, safety and general equipment
shall be carried on board the yacht to the specification
of the Sailing Instruction and the applicable Category of
Offshore Racing Council Special Regulations governing
minimum equipment currently in force.
15.3 Two batteries each weighing a minimum of 29kg shall
be carried in the battery compartment aft of the main
15.4 There is no restriction on radio or electronic aids,
but automatic, mechanical and wind vane devices for
steering must not be used when racing unless specifically
permitted in the Notice of Race or Sailing Instruction.
15.5 Minor modifications to enhance the safety and
comfort of the yacht are permitted, subject to approval
of the Class Committee.
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 for the Committee to exclude from all
Sigma Class racing any yachts claiming an individual
16.2 Only approved equipment specified in these Rules may
be used in the Sigma 38 OOD Class and no changes may be
made to equipment or fittings without reference to the
16.3 Changes in the approved Class Equipment Suppliers
shall be authorised only by the Sigma 38 OOD Class
Association which may delegate this responsibility to the
Committee in consultation with Builders.
|17.0 Exotic Materials
17.0 Exotic Materials
17.1 The use of exotic materials is prohibited except in
|18.0 Crew Limitations
18.0 Crew Limitations
18.1 The maximum Crew Number shall be nine for Class and
IRC racing. The notice of race, the Sailing Instructions
or the Class Association may change this limit.
|19.0 Crew Qualifications
19.0 Crew Qualifications
19.1 When racing under a Class Certificate the skipper,
whether owner or not, and any helmsperson must be members
of the Class Association. The Sigma 38 OOD Class
Association Committee may make special arrangements for
Service, Sailing School and Chartered Boats.
19.2 The Skipper (whether owner or not) and any
helmsperson for the Offshore and Inshore Races of the
National Championship must have been members of the Class
association for at least three months prior to the start
of the Series, and at least half of the crew including
the skipper and the helmsperson (rounded up) must have
sailed at least four races in a Sigma 38 OOD since the
end of the last National Championships. Special
dispensation may be granted at the discretion of the
Class Association Committee in respect of yachts under