Technical Committee Ruling No 1

Request for Rule Interpretation No. 1 Decision by : Brett McCormack (Chairman, NZL), Bill Hagerup (USA),  Angus Richardson (GBR)

Date: 13 Jan 2007

Effective immediately

My primary question surrounds the Length (Depth) that the Rudder my extend on the Vertical Axes for the Footy. "By reading the Rules there doesn't seem to be an exact determination of what the Overall Restrictive Length of the Rudder might be. There is however the assumed 200mm slot but no formal rule to provide for this eventuating."


FOOTY CLASS RULES for radio sailing These are open class rules in which anything not specifically restricted or prohibited is permitted. B. PRIMARY MEASUREMENT RULE

B.1 With the exceptions listed below in B.2, B.3 and B.4, the

boat in racing trim shall be capable of fitting into an open-topped rectangular measurement box of internal dimensions 305mm long, 305mm deep, 153mm wide, with 6.3mm wide slots for projecting spars and rudder, as shown in the diagram. B.2 The following may project above the top of the measurement box:

sail(s), mast, spars, rigging, aerial, associated fittings. B.3 A

bowsprit may project forward of the measurement box. B.4 The following may project aft of the measurement box: bumpkin, rudder.

E. HULL APPENDAGES

 E.1 The overhang of the rudder is restricted to 51mm aft of the measurement box.

E.2 Except for the rudder, the following are prohibited: retractable and or movable hull appendages .

 E.3Rudder thickness shall not exceed 6.3mm. E.4 Materials shall not be of density higher than lead; 11300kg/m3.

Also in addition to this there is somewhat of a confusion on my part re the Construction of the Box. I've seen many tact's with some made from simple Ply to others made from 20mm MDF Board. Each have varying restrictive degrees on how a boat can be placed. The more robust teh construction of the Box in effect brings into play the 200mm guide slot to allow rudders which attach or are positioned under teh hull. In progressing a Rule Interpretation I have provided for an attachment which hopefully explains what I am contemplating, albeit with a straight rudder and not one as described in my suggested alternative. In summary  

  • Assumed the Boat is placed in the Box along the Vertical axes and is not slotted in from a variety of Axes merely to overcome a restriction or conversely to deny a competitors right to address the rules as they stand.
  • A rudder Attaching Post extends from the boat through the "V" to no more than 51mm aft of the interior of the box.
  • with a box construction of 1mm ply this could mean a maximum rudder width of 50mm.
  • A Vertical hole for Inserting Rudder is drilled through post.
  • The Rudder is attached through hole on rudder post by Tiller Arm Fitting.
  • The Rudder of varying length up to 250mm (possibly out to 305mm without ballast restriction), yet not more than 6.3mm in thickness, can be attached via rudder post with no part of the rudder entering the slot in box.
  • Can the Push rod be bent (say 90 deg) to accommodate a longer Tiller Arm? This might extend beyond the "V" but still fits within the box if placed from the vertical axes.
  • Construction Material could be Carbon Fibre, Glass, Ply, Aluminium or any other material lighter than current ballast.
Additionally can there be an Alternative consisting of;
  • varying shapes of rudders that could have a portion under the boat
  • extending downward and exiting the slot at less than 200mm
  • with a Vertical Thinner trailing section extending further downwards.
  • At no time extending along the Longitudinal axes greater than 51mm aft of the internal of the Box
Pros
  1. Greater Steerage Control in Gusts.
  2. Marginal Performance Increases to Windward
  3. Negligible but minor Benefits Running
  4. Improved Tacking in higher winds
  5. possible reduction in Ballast weight giving greater steerage control and increased all round performance due to weight displacement.
  6. Less Weight - Less Force Require to move static object.
  7. Greater Sideways Resistance against force of wind enabling a reduction in notional ballast
Cons
  1. Greater Drag
  2. Greater Weight depending on construction.
  3. Perception of unfairness and outside spirit of Box Rule 200mm Slot
  4. High grade Servos Req'd
  5. possible reduction in ballast weight and perception of using rudder as ballast
The only limitation on what I am proposing is where it states at Rule B:1, where it states, "the boat in racing trim shall becapable of fitting into....as shown in the diagram ".

This could be interpreted that some portion of the Rudder must fit within the confines of the Box. From here however my Alternative rudder configurations would seem to be applicable.
Can you investigate whether my Rudder Length is a problem within the rules and whether there should be a formal Interpretation Issued to clear-up any misgivings about what size rudder/ Length of Rudder can be used.
As an aside there has been some mention of foil rudders which if attached in my estimation would exceed the greater thickness of 6.3mm for the rudder. Are Foils on Footy's permissible by way of attachment to the rudder and thereby not allowing passage through the slot.
My suggestion of longer than the box was merely to get the members of the Forum thinking of the possibilities where some unscrupulous sailors might try to exploit the rules to their benefit. To some degree this was successful, if somewhat naive on my part given the aversion to addressing rules and regulations within a developing Class .

Decision
  1. A rudder as suggested is legal so long as it is no more than 200 mm deep at the point where it passes through the slot in the box (if at all) (Arg.4).
  2. A foil on a rudder projecting aft of the measurement box is legal provided that it forms part of the rudder and the total thickness of the latter does not exceed 6.3 mm (Arg.5).
  3. The box is to be taken as a notional set of plane surfaces. Any intersection with the physical fabric of the box shall be regarded as a practical problem on which the class association should provide guidance, and not per se grounds for illegality.
Recommendation ON REVISION OF THE RULE:
The diagrammatic and textual versions of the class rules should be brought into line with one another.

Amend Rule E1 to read as follows;
  1. The overhang of the rudder is restricted to 51mm aft of the measurement box.
  2. The depth of the rudder at the aft limit of the measurement box is restricted to 200mm below the top of the box.
Argument
1. Does the diagram form part of the rule?
      ... the boat in racing trim shall be capable of fitting into an open-topped rectangular measurement box of internal dimensions 305mm long, 305mm deep, 153mm wide, with 6.3mm wide slots for projecting spars and rudder, as shown in the diagram. (rule B1)
    Therefore the diagram does indeed constitute part of the rule.

2. Application of preamble to rule.
    The prime rule of interpretation is that
    anything not specifically restricted or prohibited is permitted. (Preamble). The 200 mm slot which forms the basis of this application appears in the diagrammatic version of the rule. The true question is what limitation or restriction that 200 mm slot represents. It is common ground that there is a restriction of 200 mm on the depth of the rudder at the point it crosses the aft reference plane of the box.

    There can be little doubt that the rule is inconsistent in that the written version does not mention the depth of the slot, whereas it does mention the width (rule E1).

3. 'No uniform material used for box construction ...'. (Requestor's comment on diagram)
    Since no material thickness is specified, it must be assumed that the box is indeed notional. All measurements (including the aftward projection of the rudder) are taken from the hull measurement plane of the box (i.e. its inner face). Note that in the diagrammatic version of the rule, the word 'box' is always written thus (i.e. in inverted commas) and that the gauge for rudder projection shown on the diagram of the box has its dimensions taken from the inside of the box.

4. Reference point.
    Since it as apparent from (3) above that the point at which the 200 mm limit is measured is a horizontal line on the reference plane (i.e. the inner face of the box), there is no specific prohibition or limitation applying to the depth of the rudder other than along that line.

5. Foils
Treating the question of foils on rudders as part of the request, only a rudder (or bumpkin) is allowed to project aft of the measurement box (rule B4). Hence, anything of that nature projecting aft of the measurement box, if legal at all, must be subject to the limitation on rudder thickness of 6.3 mm. Subject to the proviso that the rudder is used primarily to affect steerage (ERS E.1.10), its sectional shape within the 6.3 mm width limit is not subject to any limitation or prohibition within the rule. The density of the material used must be less than that of lead, but is otherwise irrelevant so long as the extension falls within the definition of ERS E.1.10.