INTERNATIONAL SAILING FEDERATION
RADIO SAILING DIVISION

NOTE! This is the WWW version of the Interpretation. In the case of any divergences, the original document applies.

INTERPRETATION ON THE INTERNATIONAL A CLASS RULES

Clarification requested by David Coode, GBR, as follows:

1   Does the Australian boat A-1 reg. no KA 271, first measured before 1994, and built with a circa 25 mm negative camber from the forward end of "J" to the transom comply with the 1985 class rules and the 1994 class rules. The boat has a beam with convex upwards camber and a section of circa 30 mm fore and aft x 1 mm deep running from deck edge to deck edge at the mast position to which the height of the rig is measured. The mast measurement mark is placed on this beam. The lower mast measurement band is placed in line with the top edge of the boom and below the cambered beam.

2   Do boats with the lids of screw top pots and similar containers for remote control equipment protruding above the deck comply with the 1985 class rules and the 1994 class rules?

Relevant Rules (1985)

3

Freeboard

Freeboard shall be defined as the height above LWL of the junction between the upper side of the deck and hull. This shall at each station of measurement be determined as the lowest point of contact between the hull and a tangent of 45 degrees to the horizontal plane. Rail, fender, or other projections not be included (see Fig. 2).

4

Sheer

Sheer shall be a fair and continuous concave curve.

7

Camber of Deck

The camber of deck at any point must not exceed one twenty-forth (1/24) of the beam on deck at that point.

Discussion (1985 class rules)

The 1930's version of the class rules limited "the round of deck beams ...". This can be clearly understood to be either positive or negative. By 1985 the class rule had amended the restriction to camber. Camber is commonly described as a convexity so we can read class rule 7 to mean "The convexity of deck at any point must not exceed one twenty-fourth (1/24) of beam on deck at that point". As this is a development class and anything not restricted is permitted, we can understand this to place NO restriction on deck concavity.

The sheerline of the boat does not infringe class rule 4 and there are no restrictions placed on the height of the lower mast measurement band.

It is noted that the "Rail, fender, or other projections" are not included in the method of determining the freeboard measurement point. One of the diagrams in Fig. 2 shows a rail, circa 5 mm deep, mounted on the deck a small distance inboard from the deck edge.

The diagram shows its presence is ignored in determining the freeboard. Taken to the bow, where the deck is less than 120 mm wide, this rail would probably contravene the camber restriction, rule 7. It can be taken, then, that the "Rail, fender, or other projections" shall not be included when determining the camber at that station.

Likewise a protruding pot lid, a hatch coaming or hatch cover, may be considered to be a local modification to the deck shape projection and for the purpose of providing access to the interior of the hull. They are therefore local projections above the deck intended to be permitted. In contrast a cabin, coach roof or cockpit and similar structures are not considered to be local modifications to the deck shape and are therefore not intended to be permitted.

Decision (1985 class rules)

The boat A-1 complies with the class rules with respect to deck camber and rig measurement.

Lids of screw top pots and similar containers, hatches and hatch covers intended to provide access to the interior are not considered to form part of the deck and are not subject to the restrictions on deck camber.

Relevant Rules (1994)

3.2.9

The DECK EDGE at any section is the junction between the deck and the top sides. This is taken as the lowest point of contact between the hull and a tangent at 45 degrees to the horizontal. Rail, fender or other projections are to be ignored.

3.6.5

Deck Round

The deck round at every section between a point 25 mm aft of the foremost point on the hull and the aft freeboard measurement point shall not exceed one twenty-fourth of the local beam measured deck edge to deck edge.

Discussion (1994 class rules)

The class rules have reverted to what is though to have been the original intent by limiting overly convex and overly concave decks.

The same approach is taken to "Rail, fender or other projections" as regards to the deck edge and freeboard measurement. Therefore it is taken that the same logic can be applied to these items, cabins, coachroofs and cockpits.

Decision (1994 class rules)

The boat A-1 does not comply with these class rules with respect to deck camber.

Lids of screw top pots and similar containers, hatches and hatch covers intended to provide access to the interior are not considered to form part of the deck and are not subject to the restrictions on deck camber.

Graham Bantock
ISAF-RSD Technical Committee Chairman

These interpretations were ratified at the PC Meeting 10 January 1998 and have the status of class rules from this date.