Rules and rudders

Most people I see with rudders up is because they haven’t noticed or because they don’t actually know they should be fully down. 

Originally posted by GML Originally posted by jeffers As others have said nothing in the RRS but class rules may prescribe that the rudder must be fully lowered during racing (like the ILCA/Laser for one). The ILCA/Laser class rules actually allow you to sail with the rudder raised in shallow water: "14.(j) The rudder shall be maintained in the full down position except whilst racing in water less than 1.5m deep unless otherwise specified in the sailing instructions."

I'm sure I have heard of the Aussie Musto Skiffs regularly sailing with dagger style rudders half up in some conditions

Originally posted by 423zero There is also a substantial increase in load through the rudder and associated fittings, possibly leading to breakage.

There are classes which require the rudder to be fully down at all times, but that's a class rules thing. There is nothing in the racing rules of sailing requiring you to sail with a rudder at all!
What isn't permitted is to use the rudder for paddling or sculling, to propel the boat or even scull the stern round in a tack, but although having the rudder part up may make such illegal actions more effective, its not banned per se.