Downwind Spinnaker Trim

DW1_X35Downwind sailing can be frustrating or exciting, and it often seems there is little in between these two emotions. Why is this?

Much of the problem is to do with the boats own motion and the wind itself. When we sail upwind the boat’s own speed (apparent wind speed) is added to the wind’s speed (true wind speed)and therefore even in light winds the boat feels alive. However, turn away from the wind the opposite happens, and every effort you make to increase the boat’s speed, the less wind there is to power the sails. When reaching, the middle position, then the wind speed is the same as the sails feel – it is closer to the true wind speed.

So how do make the best of this dilemma?

In light winds then we should not point the boat dead downwind – better to come up a bit, until the boat comes alive again, the sails fill well, and the helming is easier. But… not too far up that you are not going close to where you wanted to go! You need always to balance where you need to get too, the bearing you desire, and this feel of the sails and the boat. It is better to go quickly a little off the bearing, than go very slowly at the correct one. Velocity Made Good (VMG) is the balance of these two factors (boat speed, and bearing) that when expressed mathematically can tell you exactly the correct angle to sail for the speed you are doing – many instruments have this feature today, and is no longer the preserve of the racing boat exclusively – and has huge impact on all your sailing, racing and cruising.