This is the prime rule of interpretation to which everything else is subject.

Aligning the boat along the diagonals of the box is permissible.

On measurement all relevant parts of the boat must fit in the box at one time.

'In racing trim' means in any trim that may be used during racing. This, in turn, means that any part of the rig that falls within the box must stay ‘within the box’ while the boat is sailing.

Only one rudder is allowed.

A rudder includes any associated hangings, transom standoffs, steering gear, etc. capable of fitting through the appropriate aperture in the measurement box

A ruling (Rule Interpretation No. 1) has already been given to clarify the position on the 200 mm slot shown in the diagram of the measurement box.

More than one mast is allowed.

The word ‘above’ means ‘above and beyond’. Rig etc. components can extend aft of the box, forward of the box or out sideways from the box – so long as they are above the upper horizontal plane of the box.

Transmitters and receivers having more than 2 channels are permitted, provided that no more than 2 channels are used.

There is no restriction on the size, weight, function or number of servos and/or other actuators.

The number of batteries must be 4 – no more, no less.

AA means a battery designated commercially as AA. (i.e. a single, cylindrical, commercially available cell measuring approx. 51 mm long X 14.5 mm diameter, capable of providing 1.2-1.5 V). There is no restriction on the chemistry or weight of such batteries.