New methods have made sailing upwind through gusts easier and faster and easier to teach – these methods that make sailing easier are well known to some sailors, but are not as well or as clearly known as they should be. Many sailing books complicate the methods excessively. This is a streamlined approach as part of our online sailing lessons.
All Free Online Sailing Lessons – Index
- Sailing Upwind with less effort
- Increase confidence in Stronger Winds
- Downwind with less distress
- Gusts, Gybes and tacks easily
- Not hitting other boats and more
Last week (Read Part 1 of New Upwind Sailing methods) we talked through why it is better not to luff ( not to point the boat up) in a gust when going upwind. It is much easier and faster to ease the sheet. Boatspeed comes up quickly, the boat stays very flat and the extra speed reduces leeway.
Exiting the gust is of less importance for most, but some lose their direction because the sail seems to luff. It is not true luffing and you should go straight, not bear away.
Some of our builders got out on the water in the past fortnight to try the – go straight and ease the sheet. They said:
To ease the sheet and aim for speed in gusts instead of luffing is definitely faster and feels much safer.
Pontus Wallgren Facebook GIS Group
But what is the best way to exit the gust cleanly?
If you like, this comes down to a little bit of advice. I will explain why below.
But on exiting the gust the boat will lose power for a moment
The sail will luff. But don’t change direction.
Keep going straight, pull in some sheet if you can without oversheeting and wait a 2 to 3 seconds.
Usually the luffing will disappear by itself.
This is called a “Velocity Shift” because you are going faster than is normal for the wind speed.
You can stop reading here if you just want to try it and see if it is true.
It is. You leave the gust, the boat feels less power, the sail will luff.
But if you trust the advice and just sail straight the sail will usually stop luffing.
This Luffing of the sail happens when the Boat’s Speed is high but the wind speed has dropped
With the Oz Goose we have measured speeds that work out as efficient in racing.
In 5 to 8 knots of breeze our boatspeed is best around 4 to 4.2 knots. This is actually fairly typical for boats using hiking straps.
In a 10 to 12 knot gust we move into the “Ease, Hike then Trim” and find the boatspeed sustains at 5 knots. Actually a little bit higher than 5. Sail is a little wider and the sail may luff slightly.
The wind speed arrows and the red boat speed arrows are to scale. Both boats are in nice balance.
Boat feels good in both ranges. In 8 to 10 knots the boat is fully powered up.
Around 12 knots of wind the boat is overpowered so we have to ease sails without changing direction; the sail is eased to keep the boat flat and the boat speed goes up. The boat now has a nice loose and fast feeling. We now know that is the best way from last week’s article – right!
To recap the difference, from our club racing we have dozens of photos from last year with my boat coming out of the start often ahead but no higher than other boats. I time my starts and can sail fast. Here I am on line with the other Geese.
On our first test of this method late last year, in a similar wind I’m a long way to windward, despite sailing free, and Paul a newer sailor has been told the method and is copying me. We are both ahead and to windward of the fleet after a few minutes. You can see we are easing sails more because of the twist of our sails. The other boats are still trying to point. We are easing sails in the gusts and are not luffing in the gusts.
Thought Experiment about what happens when the wind speed drops
Imagine sailing a boat at 5knots as in the gust drawing.
And then the wind disappears completely – a dead calm. But magically your boat is still sailing at 5 knots.
What will we feel?
Same as a bicycle travelling at 5 knots when there is no wind
- 5 knots of wind in your face – same as the bicycle speed but opposite direction
- Direction of wind will be felt from directly ahead.
It is not a real wind, but a wind from movement and it changes the direction of the existing wind.
Let’s look at when there is a 5 knot wind from the right side and the cyclist is at 5knots.
Then the wind in the face combines with the true wind to give a wind coming from 45 degrees from the front and on the right side. The two wind sources split the difference.
This wind direction from combining true wind with the wind of movement is called “Apparent Wind”
Same thing happens when we are sailing.
Looking at Real Boat Speeds from GPS and seeing what really happens to Apparent Wind.
I’ve worked out the apparent wind direction accurately in the diagrams below – the wind direction we feel (And the sail “feels”) changes with changes if the actual windspeed changes.
The wind direction you feel (solid green lines below = apparent wind) is different from the actual true wind direction (blue lines below). Boat velocity is shown by the red line.
Note that the boat is heading in the same direction in all four drawings.
A – Boat Speed of 4knots is correct for 8knots of wind – Sail is powered up – no luffing.
B – Gust – Ease Hike and Trim so speed increases to 5knots and sail will be luffing slightly as it is eased to keep the boat flat. The old apparent wind from A is the dashed line. The new apparent wind is the solid green line.
C – Gust ends – True Wind is now back to 8 knots but boat has not slowed. See the Apparent wind is now (solid green) from more in front of the boat than previous – dashed green is a copy of apparent wind in drawing B). So the sail will luff. AT THIS POINT CONTINUE TO GO STRAIGHT. Let the speed drop back to the right speed for 8knot wind.
D – Speed has now dropped and apparent wind direction is the same direction as in A, luffing disappeared as the excessive speed disappeared.
Review of what happens when leaving a gust
During the gust we are going faster if we use the Ease, Hike and Trim to keep the boat flat. Even more true of trapeze powered boats.
Sailing out of the gust the True Wind Speed decreases which makes the sail luff because the boat is going too fast for the windspeed.
But if we wait a few seconds the boat speed goes down and the luffing stops. If it has not after 3 to 5 seconds, maybe there has been a wind direction change or we are not quite steering straight.
A tiny bit extra for free.
Look at B again when the gust has hit.
The solid line showing the apparent wind has moved back allows us to to point a tiny angle higher. Around 2 to 3 degrees.
It is a TINY angle and not intended to get rid of heeling. Here is how to visualise the angle stolen from astronomy. Nice to know
Hold your arm out at full length and stick up two fingers side by side (touching or someone might be insulted). That is the angle – IT IS VERY SMALL.
But the boat can be taken that tiny amount higher when the gust hits “B”.
However, remember when the wind drops the apparent wind does swing forward “C” so may have to steer back down that tiny amount after the luffing disappears.
