Was recently reading a tactics book by Stuart Walker which was first published in 1966. In it he refers to a balking rule. This, as far as I could ascertain, restricted last moment alterations of course by a starboard tack boat meeting a port tacker. Now I assume this term has long ago bitten the dust, but how do the rules cover this scenario in 2005.

Prior to the start, where there's no proper course, is there some sort of cut off point after which when a port tacker has already made an avoidance maneuvre a boat on starboard can no longer alter course towards the avoiding boat?

This rule arose in the context of explaining how sailing on port tack amongst lots of starboard tackers prior to the start could actually be safer as you wouldn't be subject to this 'balking' rule.

Yes "Clocking" is not allowed...

A right of way boat is not allowed to change course if it requires the give way boat to make an immediate move to avoid a collision.

You've been reading Stuart Walker's books then. That explains a lot. No wonder you are confused. Dreadful pompous tomes.

Rule 16.1 is the answer to your question. Look it up.

Quite a few of American tactics books explain how you can approach the start-line on port and flip neatly onto starboard at the last moment. Thing is, in the USA, because of the geography, they rarely get the big fleets we do. Try the same thing at a big UK open meeting and you will be stuffed. There are rarely the gaps between the starboard tackers to get away with it. That, at least, has been my experience.

If you are a starboard tacker reaching along the line, you can usually prevent a port tacker tacking underneath you quite easily. If he shows signs of doing so, bear away and aim roughly at him. He will have to bear away too. So long as you do so early enough so he can keep clear, this is legal and prevents him tacking to leeward of you (16.1 applies). Obviously once the moment he can tack has passed, you head up again - you don't keep hunting him down, which is illegal.

Given that I'm not exactly the only person in the world doing this, sailing on port in a crowded fleet with less than, say, a minute to go, is unlikely to be a "safe" option.

Dave Perry's book on tactics is much better and there is an updated version for the post-1997 rules. I got the routine above from his book.

I sail in Ireland, Stefan, where the fleets tend to be much smaller - probably more like the US than England. So, Walker's tactic can be applied here. But then again you really do need good boat handling skills and spacial awareness to get away with it. A less competitive fleet helps too!

So, on approaching a port tacker on starboard you can legally bear off to a point where he has to duck you, being no longer able to tack into a leebow position? Then, after its clear he's borne off to avoid a collision, you can't bear off any further as this would fall under 'hunting', 'clocking'... etc.

And yes, Walker does come across as a bit pompous, even archaic in his prose.