How to reduce drag
Just about any time when we’re racing our mission is to go faster than the competition, and if we are cruising, the sooner we can make it to our destination, the better. British Keelboat Academy Head Coach, Niall Myant, shares a secret
Understanding how to get the best sail shape for your boat, for all conditions and situations can feel exhausting – and most people brave enough to dive into the neverending spiral that is long articles on aerodynamic science quickly run out of enthusiasm. So, let me suggest that we take a moment to improve our speed from the other side of the equation: drag.
All boats produce drag, and as we get faster we produce even more. At higher speeds the bow wave gets bigger and, combined with other e ects, the total amount of drag ramps up. Once the drag – which is trying to stop us – equals the same as the power from the wind pulling forward, the boat stops accelerating and stays at that speed. In other words, if we increase the power we will go faster, but if we increase the drag we will go slower.
A huge part of sailing – and racing in particular – is about getting in the strongest wind, and having more power as a result.
Race teams might have one person whose sole job is to look for wind on the course, perhaps even climbing the rig to get the best view. If we put the same energy into finding ways to reduce our drag, it would have the same e ect as sailing into more wind. Upwind we’d go faster, higher or both. To put it bluntly, there is little point worrying about the condition of your sails if you sail with sheets dragging in the water.
There’s also another thing to consider. As sailors we’ve all stressed about a small piece of tape that’s peeling o in the wind, or a crew member standing in the jib slot, or slight crease in a sail. But instead we should be looking lower, at what is happening in the water.
Why? Well, water is much thicker than air, approaching 1000 times the density, so equipment dragging in the water has a far more serious impact than something of a similar size dragging in the air.
I don’t wish to get deep into the science, because there is no need to. We want to go fast, and we can do that by finding more power or by making the boat slip through the water more eciently. Sometimes that means sanding and smoothing the bottom, sometimes shifting crew weight, and very often, simply checking over the side.
Remember, lifting a sheet out of the water is like finding more wind.