Wind and windage

What happens

Windage is everything above the water that the wind can get hold of: hull, coachroof, mast, sprayhood. The wind acts on these topsides and pushes the boat to leeward, while the current acts on the underwater hull. The more hull there is out of the water, the more the wind has to grip: a few extra metres of length soon mean a lot more windage.

The wind’s effects are greater at low speed, and above all with the boat stopped, because then you can no longer steer. In harbour, that is exactly the speed you manoeuvre at.

The bow blows off

The wind doesn’t push evenly on the boat. On a modern yacht the bow is high and shallow, while the keel, rudder, propeller and weight are aft of the mast. The bow acts like a sail and the wind blows it off downwind.

So a boat with no way on doesn’t stay head to wind: she swings round and lies beam-on. A motor boat with a wheelhouse often ends up 100 to 120° off the wind; a yacht with her sails down swings more slowly, thanks to her keel and wetted area.

Going astern, the stern comes up into the wind

It is the same thing seen from the other end. Going astern, the bow blowing off brings the stern up towards the wind: the “stern seeking the wind”. It doesn’t take much to pull the stern up towards the breeze and keep it there: almost any boat will motor astern well upwind, stern to the wind.

Conversely, going astern with the wind behind you is hard: the bow is inevitably blown off one way or the other. Setting off astern without the stern to the wind loses you control.

How to use it

• Stern to the wind to go astern. It is the most stable starting position for steering astern. In a crosswind, try to get the stern into the wind as quickly as possible.
• Keep way on. You only get steerage astern by having way on and moving positively through the water. See Carrying way.
• Allow for prop walk. Going astern, it will push the stern to one side: knowing it is coming, be ready for it before you go astern. See Prop walk.
• Make use of a bow already downwind. When the bow is already pointing downwind, it takes little speed to stay in control; head to wind, you need more to stop the wind blowing the bow off.
• Practise holding the boat in place going astern, stern to the wind.

Pitfalls

• Slowing down too early. With no way on, wind or current turns the boat beam-on.
• Leaving no room to leeward. The wind carries the boat away: keep space on that side so you have time to manoeuvre. Going astern, the bow swings out: leave it room.
• Waiting too long for the rudder. A shallow-draught boat can be blown around by the wind at speeds too low for the rudder to bite.