In 1964, I was and learning to sail on Watkins Lake, a 250-acre inland lake in southeast Michigan. On Saturdays I would race Sunfish and on Sundays crew in Snipes and Thistles. When the wind was from the southwest or northeast, our upwind legs would be as long as one mile. The more I sailed, the more I recognized wind patterns. In 1968, in my excitement and compulsion, I started to log information about upwind legs and starts, not only on my home lake but also at other venues where I competed. Over the years, this enabled me to make educated guesses about upwind legs and starting line patterns. My initial intent was to use this information to help make decisions for the upwind legs and starts at regattas; little did I realize that this crazy habit would turn into a huge data set that could help others make strong statistical calls.
For each venue, my log detailed which side of the starting line was favored in different wind directions and which side of the windward leg was favored. If a regatta had seven Olympic course races, I would record seven starts and 21 windward legs. In my earlier years I averaged about 16 regattas a year all over North America, but mostly in the East and Midwest. Later in life, I averaged about eight regattas a year. In all, racing took me to 24 states and 13 countries.
I’m still logging data today, 47 years later. The result is a huge statistical set: 10,000 windward legs and more than 3,700 starts. In 2012, I began the long two-year process of entering the data from all of those windward legs and starts into a statistical profile. It’s critical to understand which air mass you are sailing in, as all of the statistical probability tables are exclusive to the air mass. Fortunately, most single-day sets of races are usually in just one airmass type. The data was recorded in four basic wind groups: continental polar air mass, maritime polar air mass, continental tropical air mass and maritime tropical air mass.
The continental polar air mass is more common in the spring and fall. The wind is out of the north or northwest, skies are partly cloudy to cloudy, and it generally follows the arrival of a cool or cold front. With the divergent air mass pressing down on the earth’s surface, it’s characterized by short, intense puffs. Of the four types of wind masses, the continental polar has the largest oscillations, with windshifts as great as 30 to 40 degrees.
The maritime polar air mass is perhaps the most difficult breeze to sail in and, east of the Mississippi, is generally the blustery northeaster. This air mass contains a lot of moisture and clouds, making it difficult to see puffs on the water. The puffs in this air mass can be less pronounced and oscillations slow in movement, making it much different from a continental polar air mass.
A continental tropical air mass is generally a summertime air that primarily affects the midsection of North America. Its major source is central Mexico. It pulls up very warm, dry air that moves as far north as 45 degrees N. With hot days and lower humidity, there are large oscillations and variable velocity changes.
The maritime tropical air mass differs from its continental cousin in that its source is either the Gulf of Mexico or the southern Atlantic. As a result, it’s more humid, although the temperatures are not as hot as for the continental. In some places it’s referred to as a “smoky sou’wester” because humidity obscures long-range visibility. Here you’ll find lazy wind oscillations. Each of the four air masses has unique properties. Once organized into the four basic wind categories, the sailing log was simple. For starting information, I had three choices: Boat, Middle or Pin (B, M or P). I recorded which section was favored, which was not necessarily where I started. I did the same thing with windward legs. There were three choices: Left, Middle or Right (L, M or R). Again, I logged not the course that I sailed but which side of the windward leg was favored. The intent of this data set is to provide quantitative facts about the probability of one side of the windward leg being favored. Keep in mind that the data was based on which side of the course was the fastest route to the weather mark, not necessarily the course I sailed. Here’s what the data shows:
Continental Polar Air Mass: This data set included 4,126 windward legs. Of those legs, the middle paid off 2,352 times, or 57 percent of the time. The right side worked best 949 times, or 23 percent of the time, and the left side on 825 upwind legs, or 20 percent of the time. The conclusion? In a continental air mass, you’ll be correct more than half the time if you stick to the middle.
Continental Tropical Air Mass: My data was smaller in this air mass, with only 302 windward legs, but it still provides an important statistical outcome. Here the left side was favored on 154 legs, or 51 percent of the time; the middle worked on 79 legs, or 26 percent of the time; and the right side paid off on 74 legs, or 23 percent of the time. No flip of the coin here — when it goes tropical, head left. Maritime Polar Air Mass: I sailed 1,107 upwind legs in these conditions, and the right side paid off 454 times, or 41 percent of the time. The left side was favored 421 times, or 38 percent of the time. The middle was fastest 232 times, or 21 percent of the time. The verdict? Pick a side and avoid the middle.
Maritime Tropical Air Mass: This wind group comprised the biggest set of races in my data set. Of the 4,528 upwind legs in maritime tropical air, the left side was overwhelmingly favored in 3,350 legs, or 74 percent of the time. The middle is not the place to be, as it was favored on only 181 legs, or 4 percent of the time. The right side was better, but still not as good as the left, on 996 upwind legs, or 22 percent of the time. Only the biggest gamblers would go against a 75 percent winning percentage in a maritime tropical air mass.
Besides the statistical review of favored sides, I also gathered data about my strengths and weaknesses at starts and in upwind sailing. By creating your own log, you can evaluate your strengths and weaknesses in various conditions. My best breeze performance was in maritime tropical masses with sunny skies. My biggest weakness was sailing upwind in a maritime polar mass, especially in cloudy conditions.
If you ever serve on the race committee, you will learn that one boat over early at the boat end can block the spotter’s view of the entire starting line and lead to a lot of general recalls. That’s one reason why the pin end might often be favored. Additionally, the RC boat is often under private ownership, and to minimize the potential of a racer running into it, the committee will often make the line pin-favored. So conventional wisdom suggests that, all else being equal, you should start at the pin end. My data quantifies that assumption. Of the 3,727 starts in my data bank, 2,646 of them were pin-end-favored — a whopping 71 percent of the time. It made no difference which air mass was present or which side of the windward leg was favored. That’s why it can be challenging when the pin end is favored but you want to go right; then you must balance the advantage you’ll gain by starting at the favored end of the line with the ability to more quickly get to the favored side of the course.
The tactical world of sailing is complicated and confusing, and each day and wind group brings a new set of decision variables. I have never been a sailor of high risks when racing upwind, but I’ve often found myself confused about which side of the course to head for after the leeward mark. Now, in the back of my mind, I have this footnote of data that I may use at critical decision points. My datalogging compulsion will continue into future years. At 62 years old, I am in the third weather leg of my racing career, but going back and reviewing data from 1965 makes me feel like a kid all over again.
