Rudders are open for the 14 and 16. There are weight and shape rules in the rules book.
http://www.hobieclass.com/site/hobie/ihca/downloads/classrules/RBook050401_1.pdf
1. RUDDERS AND RUDDER ASSEMBLIES
1.1 Rudder blades made of another material yet
conforming with the size, shape and minimum
weight of the standard rudder blades may be
used. Rudder blades must conform within the
minimum and maximum dimensions that are
found within the profile plans. Profile plans are
available through the IHCA.
1.2 The maximum thickness of a rudder blade(s)
shall not exceed 1.015 in. (25.8 mm.), tapering
over a distance of 2 ft. (60.96 cm) to a maximum
thickness of 1/2 in. (12.7 mm), 2 in. (50.8
mm) from the bottom tip of the rudder. These
dimensions are for reference purposes only.
Please refer to profile plans for exact dimensions.
Profile plans are available through the
IHCA.