The club 420 class has now allowed the use of an electronic compass as long as the compass only uses the heading and timing functions.
Please see the new class rule below: This is effective June 1, 2017
11.9 One compass and bracket may be mounted to the mast no holes are cut or drilled in the buoyancy tanks or spars. A compass may not be installed in an inspection hatch cover. If electronic, only a compass with heading, heading memory, and timing functions is permitted. Other electronic devices except a digital timing device, electronic compass, and a camera are not permitted to be carried on board while racing.