Hi Gary,
I think I'm right in saying that if you wrote the article and the mag simply published it, the copyright rests with you. HOWEVER, the final layout and any editorial changes of the finished article will rest with the magazine. So:
1. Shouldn't be a problem however many magazines you send the original material to.
2. If you were to ask Aus Sailing about reproduction permission they would most likely grant it (UK mags usually do) BUT you do have to ask!