Lake Sailing Tactics and Choices

There are fundamental rules to follow when racing on a lake, and when the shorelines influence the wind, it pays to follow your instincts, too.

Sailing on Lake Garda

Sailing on Lake Garda

When the topography of the shoreline influences the wind flowing across the racecourse (as it does on Italy’s Lake Garda), getting to the advantaged side is essential.Mark Lloyd/DPPI

Sailboat racing is always about choices: starboard or port, right or left, higher or lower. A sailboat racer is always ambivalent; good reasons impel us to do one thing and equally good reasons impel us to do the other. There are always two options, and we should be aware that both options are regularly attractive. Success requires that we make up our mind and act. Our instinct will usually be correct, and we must not dither. Those who fail at the game tend to be ditherers.

This need to make choices is particularly evident when sailing on small lakes. In two recent regattas, on the Traunsee and the Attersee in Austria, I was repeatedly required to decide between two major options: to head for the advantaged side of the lake (there always was one) or to tack in an oscillating header. I soon realized I did better when I spurned a careful calculation and instead followed my instinct.

In the variable winds of a lake there is rarely time to weigh the influence of important factors, nor is there certitude to facilitate a quick decision. Either of the two possible choices always seems reasonable: Do you tack to port to reach the advantaged side or hold an oscillating lift on starboard? Do you jibe away from the fleet at the beginning of the run or stay with them? Do you ride the gust downwind or stay high so as to get closer to the shore?

In the first race on the Traunsee I made a clear-air start at the port (upwind and favored) end of the line and led most of the fleet up the left shore toward a promontory beyond which I presumed the mark would lay and the wind would back. Unfortunately, the mark was on the other side of the lake. Boats that had tacked for that shore had the benefit of increased velocity and veer produced by divergence all along it. We rounded last.

The lesson here is not only that finding the mark is always the most important event of the weather leg, but also that on a beat up a long narrow lake, take the shore to the right when in doubt. Here the prolonged increase in velocity and the veering produced by the divergence between the segments of the parallel-to-shore flow will result in a protracted benefit that will outweigh any transitory back around a promontory on the left.

In the first race on the Attersee we had a great start at the committee boat in an oscillating lift. I was lifting above the nearby boats, but felt I had to tack toward the right shore along which (I presumed) divergence would produce more wind and a port-tack header. I tacked out of the lift toward the right shore. But a few hundred yards later when I tacked left to cover, the boats that had started down the line in the starboard lift were now crossing ahead of me in an oscillating back.

My instinct to keep right and protect the right had been correct, but I needn’t have tacked until a competitor threatened to get to my right. Instead of tacking immediately, I should’ve utilized the oscillating lift to get upwind and then, when one of my competitors threatened to cross, tacked ahead.

In the third race on the Attersee we approached the final weather mark ninth in an oscillating veer. As we bore away we could see the long jibe was on port and that everyone ahead of us had jibed or was jibing to the left. My instinct, however, was to hold on starboard and go right—to jibe away from the coming shift, a back—and I could see that further down the leg, beyond a light patch, there was dark water.

“We’ll hold this jibe!” I proclaimed.

On the layline to the leeward mark, after we had jibed to port, we could see that we had passed four boats and would finish fifth. Again the instinct had been the correct one, but it had been based on observations made going upwind. The downwind leg must be planned on the beat: Which side has the strongest wind? Which way did the wind oscillate as we approached the weather mark? Is one side of the run advantaged by a persistent shift, larger waves, or less adverse current?

Before the final race on the Attersee we tested the wind at three-minute intervals (as we always do), and about one minute before the start we recognized a huge back of about 25 degrees. We continued down the line, started on starboard at the pin, realized we could tack and cross the fleet, and did so. As the rest of the fleet realized what was happening, they tacked and followed. We were 150 feet ahead of our nearest competitor and pulling away, until we sailed into a soft spot and the fleet, now lifting on our hip, began to close. We tacked to cover, but immediately recognized that we were going against the shift by doing so. So we tacked back to port, preventing the loss of all but four boats and snagging one back.

When oscillations are big, one has to ignore the need to get to a particular shore and use the oscillation to move upwind. Remember that the wind is oscillating and don’t sail away from a coming shift to try to cover your competition.

From these experiences we can draw some conclusions. On a small lake the choice is regularly between treating the conditions as Category II—where one side of the lake is obviously advantaged and an immediate tack toward that side is required— and Category I, oscillating winds, where conditions can be managed by holding to the lifted tack and tacking in subsequent headers. On a lake, both conditions are typically present: One side of the course, one shore, is almost always advantaged, and almost all winds, being offshore, are rife with oscillating shifts.

If one shore of a lake is almost always advantaged, remember the following:

Channeling (particularly of cold winds) occurs along each shore of a lake, producing shifts that may cause one side to provide a shorter course than the other.

Narrowing of a lake causes the wind to diverge, producing a lift along both shores. Widening of a lake causes the wind to converge, producing a header along both shores, but typically on one shore more than the other.

Higher velocity upper level flow is brought to the surface by thermal turbulence over heated land, and thus in a dying wind the strongest breeze is near the windward shore.

When wind is flowing parallel to shore, the flow over land is slowed and backed by friction, and is accelerated and veered by the lessened friction over water. Consequently, the two segments converge along shores to one’s left—looking upwind—slowing, backing, and increasing in turbulence. Conversely, when the wind flow is parallel to the shore and diverges along shore to one’s right (looking upwind), it accelerates, veers, and decreases in turbulence. This is usually the most important of shoreline advantages and should be sought on most small lakes.

At the same time, gradient winds—as well as many of the thermal winds coming offshore after traversing heated land—are mixtures of upper and lower levels of flow at different velocities and different directions, which produce oscillating shifts of up to 10 degrees. A gradient wind will, in addition, include “medium oscillations,” which produce larger oscillating shifts of 15 to 25 degrees. The result is oscillating shift conditions and the opportunity to shorten the course to windward by tacking in every header beyond the median wind direction.

When racing on a small lake, a competitor should both recognize that one side of the course is advantaged and head toward it and, en route, should shorten his course by tacking in the typically present oscillating shifts.

He should always sail so that when the alternative option becomes the better, he is free to take it: He should start at the windward end of the line (or at least on the hip of nearby competitors) so he can tack when a tack is desired. He should avoid tacking to leeward of a competitor into a position that would obviate a subsequent tack. He should jibe so as to escape the dirty air and the overlaps that might later hamper his freedom to jibe.

He should hold the lifted tack from the start until other boats tack. Don’t tack until boats on the same tack to leeward go, obeying the precepts of Category I, but do tack out of the lift when any opponent threatens to get closer to the advantaged side, obeying the precepts of Category II. And when the choice is in doubt, he should follow his instinct.