Catching the first shift in an iceboat race means a lot, especially since the average beat lasts between 2 and 5 minutes, there are no compasses on iceboats and if there were it could be very dangerous. In this brief outline, I will discuss some of my techniques on detecting wind shifts before and after the start - upwind and downwind.
It is very important to try and figure out what the wind is doing before the start. The first method is to watch the telltale on your headstay and pick out a landmark in line with the telltale. Watch the telltale to see if the wind shifts left or right. If you take enough readings, it becomes easy to see if the wind is oscillating (shifting back and forth), clocking (shifting to the right), or backing (shifting to the left). In general, you always want to sail toward the first knock. In an oscillating wind, sail on the lift until it becomes a knock and then tack. If the wind is clocking or backing, sail on the knocked tack until it knocks further and then tack over to the more lifted tack.
The most effective method for detecting shifts is sailing the course before the start. This method involves mark roundings, landmarks, and is a good time to scout the ice for smooth spots or areas with less snow. Round the weather and leeward mark at least three times each: sailing the boat as if you were racing. Watch for landmarks behind the marks on your approach. This will help you to judge lay lines and whether the wind is shifting or not. It is important to pick out the landmarks you are aimed at immediately after rounding both windward and leeward marks.
For instance, if you come around the leeward mark and are aimed to the left of your landmark, you know you're on a lift and should not tack right away. If you're aimed to the right of your landmark and it is not because of a velocity decrease, you should tack. This method is good because it will help you to start the beat on the favored tack. The same method can be used downwind.
Each leg of an ice boat race usually lasts two to five minutes. In this short period of time, usually there are very few shifts so if you can start out on the right tack it is a huge advantage. Remember that when you take your practice mark roundings you do not have to sail all the way to the other mark. You could practice three weather mark roundings in a row, taking landmark readings, and then sail downwind and practice your leeward mark roundings.
The last method of checking the wind is the buddy system. This system uses a friend with similar boat speed. The two sailors take off at the same time on opposite tacks. The two sailors tack back towards each other either after a certain period of time or on a lay line for a pre-determined mark. As the two sailors come together, it is easy to see which side has the advantage.
Next, start from the same place and go for the same distance but have the sailors switch sides. This system works well for upwind and downwind, especially if the sailors stop to compare notes.
Different people use different techniques for attacking the wind shifts. Henry Bossett is a "by the book" sailor and you will always find him on the tack that is closest to the mark. Rarely will you find him in a corner or overstanding any mark. Jan Gougeon has a sixth sense when it comes to the wind. He can smell out a puff or a shift as though he has some kind of a infra-red vision.
Hopefully, you have found some good food for thought through this article. Writing this has reminded me of the different ways to watch for shifts.