Asymetric Amendments

Initial Asymmetric Spinnaker Amendments

The amendments listed below were modified after discussions between the New Zealand and Australian Associations before being included in the official Class Rules.

They are included here for interest, and historical purposes only.


Objective: To provide sufficient change to the class restrictions to allow development of asymmetrical type spinnakers

11.5.1 A retractable spinnaker boom, mounted in a permanently fixed position through or on the bow may be used. Boom shall not project more than 1800 mm from bow stem head, when fully extended. Boom shall not project more than 700 mm from bow stem head when fully retracted. Boom shall be kept in a fully retracted position while spinnaker is not in use.

Reasoning: –

A fixed pole was disregarded for the following reasons:
– too cumbersome (and dangerous) on a startline and in general sailing
– completely changes the look of the Javelin hull which we are trying to avoid
– minimal cost savings compared to a retractable pole setup
A retracted pole length of 700 mm was required to enable all boats to fit a pole that does not extend aft of the mast position when retracted.

11.5.2 A bow sprit may be fitted solely for the purpose of launching an asymmetrical spinnaker boom, but shall not project more than 400mm forward of bow stem head.
A reinforcing strop may be fitted between bowsprit and bow stem. Strop may be made of any material provided its dimensions are no greater than 50mm x 12 mm. Lowest end of strop to be not less than 50mm from lowest point of bow or projection

Reasoning: –

Whist a bow sprit is not essentially required to fit a retractable spinnaker boom, it was felt that it would assist the conversion of older style hulls. A bow sprit will provide additional support for the spinnaker pole, reducing the need for the use of exotic materials in its construction. A bow sprit reduces the total length of spinnaker boom required by reducing the size of supporting tube required to be fitted inside the hull and therefore reduces the amount of pole projecting forward of bow when the pole is retracted.

Reinforcement of the bow sprit makes the bowsprit stronger. The 50mm measurement is to ensure the effective length of the hull is not compromised, when the reinforcement is attached to the bow stem.

11.5.3 Forestay may be attached to the bowsprit, provided the point of attachment is no more than 20mm from bow stem.

Reasoning: –

Currently the forestay attachment cannot protrude forward of the bow stem. Once a retractable pole is fitted, the strongest method to attach the forestay is to utlise the bow sprit or its extensions. This measurement makes it easier to fit the forestay attachment.

11.5.4. The asymmetrical spinnaker halyard must be led from the spinnaker firstly through a sheave or fair lead placed on the mast in such a way that when the halyard is held tightly perpendicular to the mast, the projection of the halyard shall intersect the mast no higher than 5825 mm above the sheerline level measuring band, and the forward edge of the sheave or fair lead shall not extend further than 64 mm from the forward side of the mast. Other sheaves or fair leads after this first one are not restricted.

Reasoning: –

Hoist height increased to fit the larger asymmetrical spinnaker. A hoist height any greater than this would require the use of additional rigging (ie. uppers) to control the mast, which we want to avoid.

11.5.5. Spinnaker to be measured with the head, tack and clew stretched out simultaneously so as to tension the three edges of the sail equally. The total length of the luff, leach and foot shall not exceed 17500 mm.

Reasoning: –

It was felt that some sort of measurement rule was required to place some additional control over the size of the spinnaker (instead of relying upon the hoist height and pole length to control what size spinnaker could be fitted). Formulas to control the area of the kite were considered but were felt to be too complicated and too restrictive. A perimeter measurement was felt to be a happy medium. The 17500 mm measurement allows a relatively deep kite to be constructed with an area of approximately 200 sq ft.

11.5.6 The measurement rules contained in Rule 11.5.4 and 11.5.5 may only be applied to a spinnaker flown from a spinnaker boom of type described in Rule 11.5.1.

Reasoning: –

Do not want to allow a larger conventional symmetrical spinnaker to be used.

What are your thoughts on this...

Fast, Affordable, Fun