Some of you should listen to the ABC radio segment with Consumer Affairs (Perth that is). Quite informative on consumer rights.....
All the scenarios (except the 11 month one maybe) described by Legless I would deem to be fairly normal and as such if you had a "wave" boom or mast it should be fit for purpose and built to take the occasional wipeout.
If anything breaks first time and brand new I think you would have a very good case to get a replacement no matter if it was a wipeout or not. I am reasonably sure that the statement that refers to manufacturing defects only won't hold up if you go to Consumer Affairs - or whatever it is called now - because if an item is sold for a certain purpose (windsurfing is high risk according to the Stirling Council

) and it breaks "prematurely" when being used as it is sold for it should be replaced under warranty.
I do however think 11 months of hard or MIS-use would be a bit rude to try for a warranty but definitely I would if I was a better sailor and never crashed.
One thing to remember also is that for a lot of people a year quite often only equates to less than 20 or 30 uses.
The first line of defense for a retailer is "NNaah mate! You were too hard on it." and hope you give up...........
I wouldn't buy a brand again that broke in those scenarios.