During our discussion at the last advanced racing seminar, someone asked how you choose which tack will be favored downwind as you are making your final approach to the windward mark.
I asked Mark Goodwin for help on this one, because it is hard to determine as you are coming into the windward mark (much easier once you round and are heading downwind, but it may be too late by then).
First, as you are approaching the mark, you should determine whether there are any persistent wind shifts that would favor being on Starboard or Port Tack on the downwind run. If on the upwind leg, starboard tack is favored, then the opposite tack (port tack) will be favored downwind. If the favored tack upwind is port, then starboard will be favored downwind. If you are in oscillating breeze or shifts because the mark was set close to a land mass, you need to determine how long you will sail in the shift (if it is a very short part of the run, ask yourself how much you gain by being on favored tack versus needing to jibe in a minute.
If you determine that the winds are pretty square or you are not sure of the favored tack because of the wind direction, the next thing to do is look for pressure. As you are sailing downwind, which side of the course has more pressure. Pressure is always important, but it is even more important on the downwind leg where the difference between 12 knots of breeze and 15 knots of breeze can be the difference it hitting hull speed and being 1.5 knots below hull speed. If the pressure is clearly different on one side or the other, setup to get to the pressure first. Even in a minor persistent shift, this might be more important than being on the lifted tack downwind.
Third setup to make it easy for your crew. If you are flying a spinnaker and setup for a bear away set (set to continue around the mark on a starboard tack), ask yourself which will hurt you more, sailing downwind for a short time (30 seconds to a minute) before jibing onto the favored tack or trying for a jibe set and having something go wrong - a great crew can jibe set or do a bear away set and jibe quickly) an inexperienced crew will probably be faster doing their standard bear away set and then jibing once the jib is down/furled. If you are going wing on wing, it really depends on wind speeds. In light winds, it is pretty easy to set the pole on either side. In heavy winds, I find a jibe set to be easier because you can put the whisker pole out on the same side as the main with the main blanketing the sail, and then jibe the main quickly. But others find a bear away set to be easier. So ask you crew. Again, unless there is a major persistent shift or major difference in pressure, typically getting both sails working is more important than being on the best tack, but taking 1/3 of the leg to get the sail flying.
Last, I said to ignore tactical considerations, but we all know we are not sailing alone on the race course so tactical considerations come into play. It is just as critical to sail in clear air downwind as it is upwind. So if you are rounding the windward mark at the front of a big group, you need to make the decision based on tactical considerations as well as which tack is best. Likewise, if you need to beat someone in your fleet, you need to consider whether blanketing them is more important than sailing on the favored tack.
Hope everyone sails fast at Goldrush and Junior Ol' Man this weekend. Try to put some of these things into practice.