In the Laser, a common practice when there's seaweed or kelp is to "air scull" to clear weeds from the rudder. This takes two forms:

1) Straightine: heel boat way over so that rudder comes out of water, then quickly scull rudder back and forth a few times so that seaweed shakes off, then flatten boat.

2) Mid-tack: in light air, heel the boat a little more than usual, and a little longer than usual, while shaking tiller to get seaweed off rudder.

Is this legal?

By my reading of rule 42.2.d, it seems likely to be acceptable:

sculling: repeated movement of the helm that is either forceful or  that  propels  the  boat  forward  or  prevents  her  from  moving astern;

The sculling isn't forceful, since the rudder blade is moving through the air. It's literally just a couple of pounds of force to move the tiller. Also, the sculling doesn't propel the boat forward, since the rudder is out of the water. So it doesn't meet either of the criteria of 42.2.d.

Straightline air sculling, done once every few minutes, also doesn't seem to meet the definition of rocking, since it's not repeated. It's only done once.

The World Sailing guide for Laser Rule 42 common breaches doesn't address air sculling specifically. Obviously, you can't come out of a tack faster than you went in, but a sailor can air scull and still comply with this requirement.

What are your thoughts?