Summer sailing is a blast. But it can also be notoriously hot and filled with light wind. Quantum Sails’ Dave Flynn provides some downwind sailing tips for when you find yourself floating.
SAILING DOWNWIND
It can be useful to divide sailing downwind into three modes: under 10 knots true, 10-14, and over 14. If you own a relatively standard monohull, the magic true wind angle is around 140 degrees in 10 knots of wind or less. In 10-14 the optimum angle quickly becomes broader, probably somewhere between 140 and 155 degrees true-wind angle. Once there are more than 14 knots of breeze, you should be sailing as deep as you can with control.
The only exception to the rule is if your boat has a very high horsepower-to weight ratio, in which case you may sail slightly tighter angles on average, and in 18-20 knots, it will actually pay to head back up into the low 140s. If your boat is light enough, it will begin to plane and surf in this much breeze.
Now what if you don’t have instruments capable of providing true wind angle? Notice, apparent wind angle was never referenced. This is because the optimum apparent wind angle changes rapidly with relatively small changes in wind speed. A typical displacement monohull will see the optimum apparent wind angle range from 90 to 130 degrees as the velocity increases from 4 to 10 knots. This makes the apparent wind angle simply too volatile to be useful. The true wind angle remains virtually constant over this same range; hence, its power.
POINTING IN LIGHT BREEZE
First, prioritize power. If you sail a modern fractional rig with swept-back spreaders, you need to power up the rig. Increasing headstay length, easing tension on the uppers, lowers, and diagonals are key. In established one-design classes the exact numbers and proportions will be set out in well-researched tuning guides. For handicap boats there may not be specific settings, but the goals are the same:
1. Generate headstay sag to power up the headsail and
2. Create middle-mast sag to juice up the mainsail.
You would like the headstay to sag just to the point of bouncing in the waves. An inch or two of leeward sag as you sight up the mast is the goal. For boats with more traditional masthead rigs with inline spreaders you can still go for headstay sag by fully releasing the backstay, though you will need to be careful of loosening up the rig too much. On all boats a little extra pre-bend is good, so moving the mast step aft is a nice touch.
Heel can help. Heel can create weather helm and forces the boat to point. The crew would aggressively move weight forward and to leeward. This is particularly critical out of tacks or when you are trying to squeeze up to a weather mark on a thin lay line. Weight forward will put the skinny part of the boat in the water and pick the fat stern sections out, reducing wetted surface. Keep weight low. On bigger boats, down below is the best place to be. (Who really wants to watch in these conditions anyway?)
Speed is king. You have to resist the temptation to point. This may be counter intuitive, but unless you get water flowing past the blades, they are not going to work; and you will just go sideways. Err on the side of "footing" or being on the low part of the groove with telltales streaming straight aft or even showing a little heavy on the bottom set. Use the middle telltales. It is okay to steer to leeward; your weight will be better positioned, and you can see the whole headsail.
Keep on course. Steering to keep the telltales flying is important but be careful not to chase. Small changes in wind speed (little puffs and lulls) will have a big impact on apparent wind angle. In a puff the apparent wind will move aft, and the telltales will tell you to come up. You can, but a better approach is to split the difference. Ease the headsail sheet to keep the telltales flowing, turning the puff into speed first, and then ever so gradually sneak the boat up trimming slowly as you go. Don’t get greedy! If you come up too fast and overshoot, you will kill speed quickly and will have to start all over again. In a lull you will get a header, and the jib will show luff. Instead of bearing off quickly, over trim for a moment and gradually bear off. As the boat slows, the apparent wind will go back aft, and you will be able to ease and resume a normal setup. The trick is not to coast in the lulls and not give up too much distance to leeward. Constant work with both trimmers minimizes the amount the driver has to steer. Straight, with a steady state and flow is the goal.
FOR CRUISING SAILORS
If you are a cruising sailor, you will struggle to sail broader angles especially in light air. There is just not enough apparent wind velocity to fill a heavy genoa or jib designed for upwind work unless you head up quite far (apparent wind on the beam). If you want to sail deeper in light air, add an asymmetrical spinnaker to your quiver.
In the middle range (10-14 knots) both apparent and true wind change quickly. In this area it pays to get back to the basics and only rely on the pressure on the spinnaker sheet and helm as a guide. The game downwind is all about constant pressure. The more constant, the less overall pressure you will need to maintain speed.
Eventually, the pole will be able to be squared back and the boat sailed at broad angles without losing pressure. Usually, above 14 knots, it pays to concentrate on sailing as deep as control will allow. The boat is no longer going to sail much faster by heading up.
WORKING THE WAVES
Most reasonably in-tune racing sailors are aware that in light to moderate conditions you can’t sail straight downwind and should head up until there is pressure in the spinnaker and pull on the sheet. They are aware that the optimum angle changes as a function of velocity and have figured out the best angles for various conditions; when it pays to heat up, when it pays to sail low. One subtle factor often not included in this equation is wave angle.
This seems particularly important in moderate conditions when there are waves, but not quite enough breeze for full-time surfing. What happens is this: On one gybe heating up in the lulls is no problem, but on the other, heading up for more pressure puts the boat more parallel to the waves. The boat rolls more, causing spinnaker instability. The helmsperson and the trimmer don’t like what they feel and head up further. The net result is a loss in Velocity Made Good (VMG) because you have to sail well above optimum angles to get the boat and the spinnaker to feel pressured up.
Bearing off and sailing a slightly lower angle puts the boat more in line with the waves, resulting in a steadier ride. Remember, steady state and steady flow (pressure) are the key downwind. Lock in, and the waves will help. You might not exactly be “surfing” in the classic sense, but you will be getting small rides as the waves push the boat. These rides keep the speed up and consequently the apparent wind velocity. Subtle steering (keep the range small) can make big gains to leeward if the combination of a small puff and a wave can be put together.
Recognition of the wave pattern’s effect on angles can be particularly critical when trying to hold a lane. It can keep one from heading up right into the weather boat’s bad air. Remember, I am not suggesting low and slow, but a steadier ride and more constant pressure by riding with the waves instead of letting them roll the boat. It is really about using the waves to help maintain a steady platform and constant pressure.
IT’S ALL ABOUT CONSTANT PRESSURE
The game downwind is all about constant pressure. The more constant, the less overall pressure you will need to maintain speed. The trick is to avoid cycling between too much pressure and not enough, making all the right responses but overcorrecting, until the driver and trimmer are locked in a vicious game of chasing their tails.
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This article was originally published on SpinSheet.com in August, 2018.