When I just started to learn about sailing, I had asked myself a lot whether a sailboat could sail upwind. So, to answer this question I have written this helpful post.
So, Can A Sailboat Sail Upwind? The short answer is yes it can, however not directly, sailboats cannot sail directly into the wind, instead sailors use a zigzag motion to reach across a headwind. This technique is called “tacking” in sailors’ term.
In addition to “tacking” there is a lot more to getting your boat across a headwind. I will discuss all those in details in this article.
How does a sailboat sail into the wind?
As you can see in the point of sail diagram below, the sailboats are not able to sail directly to the wind direction, however, all sailboats can sail certain degrees close to the direction of the wind.
An average sailboat can sail 40 to 45 degrees dead to the wind. Some advanced vessels can even sail 30 degrees away from the direction of the wind. The 45 degrees point of sail is called Close Hauled.
Typically, when a sailboat is positioned at 40 – 45 degree angle away from the wind, that is the optimum position of the sails where the wind comes across the sails and splits in the process. This process creates high pressure on the inside of the sails and low pressure on the outside or curved side of the sail which in turn generates a type of suction or lift that pulls the boat forward with the help of keel, rudder and proper sail trim.
It is of great importance to trim the sails properly, also to hold and maintain the sails at the 40 – 45 degrees angle to be able to move forward towards the desired course.
When sailors desire to move directly to the direction of the wind they perform a movement called “Tacking”.
Tacking allows the sailors to sail forward into the wind. How do they do that? The sailors travel for some time at an angle approximately 45 degrees away from the direction of the wind one way and then it cut across and sail about 45 degrees away from the wind direction on the other side.
By moving in this zigzag fashion the sailboat will move in the direction of the wind and reach its destination.
The Sailing history
Before there were airplanes, before there were trains, there were sailboats without them the World as We Know it would have been different. Square-rigged sailboat Brought Europeans to America.
Their stable decks and massive hulls carried the people and supplies that would build San Francisco but these ships had their limitations. They were slow And they only traverse in one basic direction with the wind.
As a result of trade expansion, European sailors were exposed to triangular sails which were very common in Arabia. Triangular sails were most common on smaller sailboats though. The use of triangular sails allowed for surfing water with the wind coming directly from over the bow of the ship.
Soon after European ships adopted these new designs. Triangular rig designs changed the whole sailing journey. Now sailor did not have to wait for favorable winds anymore, they could now literally trave to any direction they desired.
Modern sailing is not all about being pushed by the wind anymore, rather it is something that is happening at the sail that makes it fly like a wing and that force is called lifts. To help us understand what lift is we dive deeper into this topic in the coming sections.
How is the lift generated when sailing upwind?
To understand how lift is generated in a sailboat, we first study the lift in an airplane. They both work the same.
Lift is a force that an airplane utilizes to fly and stay up. This force pushes the wings up against the gravity. How does it occur? The lift occurs because of a change in pressure between the top and the bottom of the surface of the wings. This phenomenon is clarified in an easy to understand illustration.
In the illustration below you can see an airfoil shape which is a representation of a wing. It is not a symmetrical shape, i.e. the top is curved and the bottom is a straight line.
When the airfoil moves through the air or the water because of the unsymmetrical shape of the airfoil, the air or water on curvature part has to travel a longer distance to past the airfoil than the bottom one.
As a result, the air or water on top travels faster than the air in the bottom. In physics, the air is considered as a form of fluid. Bernoulli’s principle states that when fluid increases in speed, its pressure decreases.
So, when the airfoil moves in the air, the faster air of the top part creates lower pressure while the slower air below creates higher pressure. So, we have low pressure on the top that acts as a suction mechanism which holds the winds up and the higher pressure at the bottom the pushes the wings up, therefore, the lift is generated. This causes the airfoil to move upward.
So, now we understood what lift is and how it is generated. It is time to discuss how lift is generated on the sails.
- Typically a sail acts as an airfoil that is positioned sideways.
- The illustration below depicts a sailboat from the above.
- The front of the boat is called Bow
- The back part is called Stern
- On the sail, there is windward and a leeward side
- Headwind blows
In this scenario the wind blows, some wind passes the windward and some passes the leeward side.
We can observe that the wind which is blowing through the leeward side has to travel a larger distance with a higher speed to catch up with the wind blowing the windward side.
According to Bernoulli’s law, this creates low pressure on the leeward side. Likewise, due to airflow, high pressure is generated on the windward side. These two pressures result in motion or force just like the wing of an airplane or simply put the lift.
If we do not consider the effect of the keel and the rudder the vessel sails generally sideways and partially forward. However, the keel and the rudder counteract the sideways force and allow the sailboat to sail forward to 40 – 45 degrees in a close haul direction.
Just as if you put pressure with two fingers on a watermelon seed, the two opposing forces will cause the seed to shoot forward.
Surfing in a close-hauled direction is the closest a sailboat can travel to the headwind. In order to sail into the wind direction, sailors use the zigzag “tacking” technique which we will clarify in the next section.
The Tacking Technique For Sailing Upwind
What is Tacking on a sailboat?! It is one of the key maneuvers that is employed by the sailors to change direction by turning the bow of the vessel through the eye of the wind.
Tacking needs good teamwork between the helmsman and the crew. Tacking is typically performed to change direction from one close-hauled direction to another however, it is not limited to this wind course only.
so, in our scenario, we can use the tacking technique to sail into the wind.
How is this done? you might ask.
We discussed earlier that sailboat can sail upwind at an angle, on most sailboats, this is 40 degrees away from the wind course.
The sailors travel for some time -at approximately 40-45 degrees from the direction of the wind -one way and then they cut across and sail about 40-45 degrees away from the wind direction on the other side. By tacking back and forth (moving in this zigzag fashion) the sailboats will move against the wind and reach their destination.
Tacking is shown in the illustration below:
How should you Trim your sails when you sail upwind?
Sailing upwind requires that the sails are set in a fairly specific way and then you can steer the boat to keep the sails at the right angle to the wind. Taking each of the sails inturns, first of all, you want to look at the sails at the front of the boat i.e. the jib.
Trimming The Jib
One of the most important maneuver to cruise efficiently and at the same time to keep your momentum and speed high would be proper trimming.
It is crucial to trim the jib properly before the mainsail. Because having a well-trimmed jib sail will have a tremendous effect on the mail trim behind, therefore you want to get it trimmed properly first.
As the primary control on a sailboat is the jib sheet, I would like to have marks on the jib sheet so that I have a valid basis to work with and return to when I either tack or when the wind shifts in speed.
Adjusting The Jib Car
The other main control would be the jib car and on most vessels, you can shift it back and forth on the track. In light winds, it is advisable to have the car further forward while in stronger airs it is most efficient to have the car further back in order to spill the top of the sail.
You can use the telltales to judge where to have the car, it is best to have all three of them breaking at the same time.
Adjusting The Halyard
Additionally, the halyard is the other control mechanism that needs your attention when sailing upwind. In order to control halyard properly you want to have it tighter in stronger winds and also the backstay needs to be tighter in stronger winds to flatten the sail.
Trimming The Mainsail
After that go ahead and look at your mainsail. Your mainsail must be nice and tight. So pull tight on your main sheet. You want to get the boom pretty much to the centerline. Once you have that in place, the next step is to get the boat sailing at the right angle to the wind.
As we mentioned before sailboats can’t sail straight into the wind however they can sail about 40 to 45 degrees away from the direction of the wind. So if we know where the wind is coming from then we should have a good idea where to point the boat.
Every individual has his or her preferred wind indicator to find out where the wind is coming from. For me, I like to use the flags to figure out the wind.
Tacking The Sailboat
Once I know where the wind is I can then angle my boat at about 40-45 degrees to the wind and start my vessel moving upwind.
As soon as we are sailing in the right direction, I can then go ahead and fine-tune by looking at telltales on the jib. When you look at the telltales you will see the yarn on the leading edge Of the Jib.
We aim to get the yarn on both sides of the sail flying straight back, that means that we have got a good even flow of air over both sides of the sails. This even airflow will generate lift that will allow us to sail upwind. That is how to set the sails up and trim for upwind sailing.