Know the Numbers

with Caroline Atwood @catwoodsails

An electronic compass is a tool that reads your boat’s sailing angle relative to true north or zero degrees.

If the wind is coming from true north, and you are sailing 50 degrees off the wind, close hauled, on port the compass will read “050” in nice, bold, digital letters. If you continue to sail close-hauled and your compass starts to read “056” and then “060” and then “065” you and your teammate now have numerical proof that you have sailed in to a 15 degree header. In other words, the wind has shifted from true north at zero degrees to the right and now is at 15 degrees.


Compasses are great and can offer us numerically quantifiable proof of trends on the racecourse and in practice. However, they are only one tool in your arsenal of what it takes to be a successful sailor and they become useless at the point that they become distracting. Here are two basic ways to start using your compass to compliment your training and racing without distracting you from the big picture:

Pre Start:

-At its best a compass helps you understand the course better and therefore it is invaluable to your pre-start and pre-race research. Three key numbers that you need to have in your mind before the first start are average starboard angle, average port angle, and true wind heading.

-To establish your average port and starboard angles make it someone in the boat’s job to glance at the compass every few seconds any time you find yourself close hauled (split tack, speed test, sail out to the course etc.). The number you see most often, or the number in the middle of an 8 to 10 degree range of numbers you are seeing is your average number. After a few glances, over the course of a minute, you should be able to report to your teammate and coach what the average heading is for each tack. For example, if your compass check-ins report 053, 050, 047, 050, 049, 051, 050 then your average angle on that tack is 50.prestart numbers

Do the same for the opposite tack and remember those two averages. Continue to check your compass periodically on every upwind from now on.

If you see the number change dramatically (more than 10 numbers) from the average in either direction make sure you and your teammate are both aware of that change. As you acquire more data points, adjust your pre-start average angles as needed. These numbers can help you track shift pre start and will also be very helpful on your upwind beats so remember them.

-The other number you must be aware of pre-start is the true wind angle. To take a true wind heading, point your bow in to wind, look at the number on the compass when the jib is hitting the mast. That number is the true wind angle. Take true wind headings regularly throughout your pre-start routine and use them to track shifts.

Compass Hacks

Numbers keep going up? Breeze is clocking right.

Numbers keep going down? Breeze is clocking left.

Numbers are flipping between high and low? You’ve got an oscillating breeze.

*Also make sure to compare your true wind angle to the angle of the top mark as reported by the race committee. Usually this number is displayed on a board on the RC boat along with the type of course. If you notice that your heading is significantly to the left (lower number) or right (higher number) of where the race committee has set the mark get ready to sail a skewed course.

On an Upwind Beat:

Remember those upwind angle numbers you collected before the start? Now is the time to use them. At any point on an upwind you can take a quick look at the compass and compare the number you see to your pre-race average for that tack. This is a quick and efficient way to determine if you are headed or lifted, to what degree you are headed or lifted (only a little headed or super duper headed), and, if you check often enough, how long the shift is.

Throughout the upwind someone on the boat needs to know and say what angle the boat is currently on and what the average pre-start angle on that tack is.

On starboard, a lower number than your pre-race starboard angle means you are headed compared to your pre-race angle. On port, a higher number than your pre-race average means you are headed relative to your pre-race angle. Any time you catch yourself sailing headed, especially for over 30 seconds, you need to have a good reason to be sailing that direction. If you forget that headed = lower than average on starboard and higher than average on port look under the number on the face of your compass. On the right side, the side you see on starboard, it should say, “tack on –” and on the side you see on port it should say, “tack on +”.

Just like in your pre-race angle reporting, make sure both people in the boat are aware when the angle changes over 10 degrees from the average in either direction. That number change is an opportunity for a strategic gain or a tactical play.  As you go up the beat, also take note of a new “first beat average” that may be developing. If it is different from your pre-race average then you have identified a shift pattern that can inform your downwind and second beat.

Once you get comfortable with these compass techniques, talk to your coach about what else a compass can do for you.

Just remember, a compass isn’t a golden ticket.

It is only useful when the boat is sailing well and it only tells you about one part of the puzzle. However, when it comes to getting quick, quantifiable answers to questions like “where is the wind right now?” and “am I headed or lifted?” it’s the perfect tool.


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