Sigma 38 


Racing Tips for Autopilots


Philip Meakins shares his autopilot tips from his experience racing his Sigma 38 Festina Lente


Modern autopilots seem little short of miraculous. The introduction of gyro capability in particular has enabled them to match and even exceed the performance of a human helm in conditions where pitch and roll would have played havoc with the performance of early autopilot models. From a racing sailor’s perspective however, the ability to sail locked onto the wind has, if anything, brought even greater performance benefits.


My experience is that the latest generation of masthead wind indicators have significantly improved the accuracy of the wind data and made sailing using the apparent wind function my default setting. This is particularly true to windward but in heavier boats like mine it pays as far back as 120 degrees true. Apparent wind is directly measured rather than being a calculated function so once the masthead unit has been meticulously calibrated you can be confident in the data coming from it.

Wind is never constant. Its variations may be a few degrees every minute and/or larger variations over a longer time scale in both direction and strength. Successful sailors are aware of this and constantly adjust the shape and setting of the sails to suit. In a fully crewed boat the helm follows these variations and top trimmers never stop adjusting but single or short handed crews may be too busy to match this constant attention to micro-detail.


Given the inherent variability of wind, if the autopilot is used to windward on compass heading mode, even in relatively stable conditions the heading is going to be less than perfect much of the time. It is far better to use the apparent wind setting so that the boat follows the wind and assuming you have the rig set up correctly, the sails will continue to deliver maximum drive despite variation in the wind direction. On a fetch or a reach, the better speed thus maintained easily overcomes the marginal extra distance sailed and the wind change alarm will bring attention to significant course changes that might require adjustment. Downwind the large change in apparent wind angles with changes in wind strength and/or waves means that I tend to use the compass course setting in all but the most stable conditions.

Ambassador Philip Meakins


In order to get the best use of the apparent wind setting when racing to windward, you need to know your boat. In light airs my fairly heavy cruiser racer goes best at 35 degrees apparent – significantly more if there is a chop. In 10 knots of breeze she likes 29 or 30 degrees, at 20 knots of true wind we might have 26 as the optimum, and in 35 knots as little as 24 if the water is flat – but much more if there is a heavy sea. I might add 2 or 3 degrees as we come out of the tack and reduce it once we are up to target speed.

Light displacement monos and multihulls may have problems on reaches or even fetches as the apparent wind changes radically when they accelerate in gusts or waves.
Lastly, you may get very confused in conditions where there is a large wind shear, as often occurs in the Solent when the surface wind follows land contours, whilst the masthead wind may be in the gradient breeze. Nonetheless, for the vast majority of the time you will be much faster with your autopilot talking to your wind vane rather than your compass.

Once you get the angle right for your boat and the conditions, the next problem is that the autopilot may be faster than you. Now that’s impressive! Try it for yourself.”