8.5 Rules

Open 8.5m Rule

(Established by the New Zealand Multihull Yacht Club 2004)

Revised 2006 V2.1


1/Intent
The intention of the Open 8.5 rule is to create a "box rule" class, based
around the principal dimensions of the popular Great Barrier Express to
stimulate fleet growth and provide much needed class racing. The spirit of the rule is to establish a class which will not promote "cheque book racing" but still allow some free thinking in design and construction and to generate boats able to be competitive both in harbour and coastal racing.
There is to be no restriction on design of or number of hulls, rigs or sails other than:


2/Length

Maximum length overall: 8500mm

The overall length is measured between the foremost point and the after most point of the boat, projected on the waterplane in rating trim, excluding prods, pulpits, rudder(s).
It is measured between the following points:
a- at the front: the foremost point of the hull(s) or the outriggers,
including bulwarks, rubbing strakes, fittings, whether above or below deck level., and excluding prods. This point will be called the "bow" for the purpose of this rule.
b - At the back: the aft aftermost point of the hull(s) or outriggers,
including bulwarks, rubbing strakes, fittings, whether above or below deck level. This point will be called the "stern" for the purpose of this rule.
The rudder(s) is (are) not taken into account in the rated length provided they have no surface, volume or appendage that would lengthen the static or dynamic length of flotation.


3/Beam

Maximum beam to outside edges 6500mm
Only sails, booms, and rigging may project outside the maximum beam at any time.
Maximum beam includes any other part of the boat and is measured perpendicular to the centerline.
Boats shall not be fitted with trapezes, hiking devices or moveable wings.
Maximum width of seat projection beyond topside 250mm(confirm after group measurement) .

4/Rig(s)

The length measured parallel to the waterplane from the fore end of the prod to the bow point as described above shall not be greater than 2000mm. This measurement shall be taken from the fore end of the bowsprit, even if the block or fitting for fixing the Gennaker tack is located aft of this end.

A prod is defined as a spar used as a fore-outrigger for the Gennaker or screecher tack.
If the positioning of the bowsprit is achieved with rigging elements (for example bobstay and side stays, etc.) they shall be tight and not adjustable when in use.
No part of rig or sails in their normal position shall extend aft of
measured transom.

Forestays shall be permanently attached aft of the bow.

Maximum air draft (total height above waterline)12600mm.

The air draft is measured between the uppermost point of the mast(s) and/or any sail (in functioning position) and the waterplane, in measurement condition. The uppermost point of the mast(s) shall be measured on any rigid point of the mast(s), including any halyard block, but excluding appendages such as lights, antennas, wind vane, anemometer, etc.

5/Weight

The minimum weight of the boat in race trim equipped to cat 5 including..

mast (s),boom(s), prod (s), all running and standing rigging, centerboards, rudders, engine, anchor and permanently attached equipment

But excluding... crew, consumables such as food, water and fuel shall be 900 Kg.
In the event that a boat is underweight corrector weights to bring the boat up to the minium weight shall be added to the boat divided equally between the two hulls in the following positions...

2m aft of the bow
2m fwd of the stern

6/ Stability
Boats shall not be fitted with trapezes, hiking devices or moveable wings.

7/ Scantlings and arrangement

The boats have to be capable of obtaining Cat 3 safety certificate.
Boats shall have at least one hull with headroom of 1600mm measured over a centreline distance of not less than 1000mm.

8/Auxilliary Propulsion

Boats shall be fitted with an engine with a minimum of 8hp.
Boats with an overall length of 7m or under shall have a minimum of 6hp.
The installation of the engine and its accessories shall be according to YNZ Cat III requirements

9/ Grandfather Clause

A "grandfather clause" allowing existing boats which do not measure to some of the above still be class-eligible at the discretion of the Open 8.5m Class Association Measurers.


10/ Eligibilty
Final decision on Class eligibility rests solely with the Open 8.5 Measurers and Class committee as established by the New Zealand Multihull Yacht Club.
To be eligible for class racing boats must be measured and registered. Once successfully measured boats shall display an 8.5 class mainsail logo as per the attached drawing.

11/ Inspection
The boat shall be measured in its usual race trim, equipped to Cat V
It is the responsibility of the owner to maintain the boat in compliance with these rules at all times when racing.
A boat may be inspected at any time. If it is found to not comply its race entry to the race and/or series may be refused, it may be disqualified or be subject of any other penalty decided by the Open 8.5 class committee.

12/ Amendments to rules

The above rules may be altered by a meeting of 10 or more 8.5m class owners. who are financial members of both the NZMYC and 8.5m Class Owners Association. A 75% majority of those present is required.

Notice of any such meeting is to be circulated to all current members of the owners association at least 2 weeks prior.

13/ Measurement

All measurements to the nearest mm or kg.

For more information or appointment for measuring conatct:


Bill Barry voomon@hotmail.com 021 2959 467