Headsail vs. Mainsail: Do You Know the Difference?

When you look at a sailboat, you will see two primary sails. These are the mainsail and the headsail. You might think that, besides their positioning on your boat, the two sails are practically the same. That actually couldn’t be further from the truth. What are the differences between the headsail and the mainsail on your sailboat then? 

The headsail and mainsail differ in the following ways:

  • Type
  • Function
  • Shape
  • Size
  • Wind speed

Curious to learn more about your sailboat’s headsail and mainsail? If so, then this is the article for you. In it, we’ll expand on the above differences, giving you all the info you need to better understand your boat. 

The Differences Between Headsails and Mainsails

Below we will list 4 main differences between headsails and mainsails:

The Type

Before we get too deep into the types of sails, let’s go over basic sail anatomy, because this will come up later in the article. All sails have a head, a leech, a luff, a clew, a foot, and a tack. The head is at the top of the sail and is the highest point. At the front of the sail, there’s the luff, which is the front edge. Behind that is the leech, or the back edge of the sail.

Getting towards the bottom of the sail now, you have your clew, foot, and tack. A clew refers to the back corner of the sail’s bottom. The foot, like our own feet, is the lowermost point of the sail, the very bottom. There’s also the tack, which is the front corner at the bottom of your sail. 

Now that we got that basic knowledge out of the way, let’s talk first about the types of mainsails and then headsails. 

Mainsail and its types 

Your mainsail, as the name suggests, is the, well, main sail of the boat. Now, this can be kind of confusing on its own since the mainsail is in the back of the sailboat, but we’ll get more into what it does and why later. 

The mainsail has four battens, which are sail inserts that enhance the quality of the sail. You should always use the direction that the wind is flowing to place your battens, putting them parallel.

Also a part of the average mainsail is reef diamonds, up to nine depending on the sail size. Every sailboat should have reefs, typically in a row. These allow you to lessen your sail area in emergencies. Too many reefs can be detrimental to your sailboat though, as it weighs the boat down. 

When setting up your mainsail, you have several ways to go about it. You can go loose-footed, where you tie the sail around your boat’s clew and tack only. You can also use the boom, attaching your sail to the bolt-rope, car, or slug. 

Headsail and its types

Besides the mainsail, there’s also the headsail. This sail earned its name because it’s ahead of the mainsail. Your headsail connects from the bowsprit or the deck by a rod, wire, or rope, keeping the sail in one position. 

Depending on the shape of your headsail, it could be referred to as a jib. This is a specialty staysail (a type of headsail) that goes in front of your sailboat’s mast.   

One type of jib is a genoa sail. It’s supposed to cross over your boat’s main sail. Besides sailboats, you’ll also spot genoa sails on ketches, yawls, and other boats with twin masters or single-mast sloops. 

You’ll often see percentages associated with the genoa sail. These refer to how much bigger this sail’s leech is beyond the mast. If it’s between 125 and 140 percent, that’s a number two genoa sail. Those sails that extend 155 percent or more are considered number one genoa sails. 

Other Sail types

There are more than just headsails and mainsails. For instance, you should also learn about the spinnaker. This can be used in very windy conditions, especially when sailing downwind. A spinnaker sail will ride with the force of the wind, puffing outward and looking almost like half a balloon. It then flies along the water.

Spinnakers go by names like chutes or kites due to their design. They’re meant to look fun and colorful, and with their nylon construction, spinnakers don’t weigh too much. 

There are yet more specialty sails that deserve some mention. These include:

  • Stormsails: Trysails and storm jibs are two types of stormsails. The storm jib is a staysail in a triangular shape. These sails have more strength compared to your average boat sail so they can withstand inclement weather. The trysail acts as the temporary mainsail during stormy conditions. It sits above the gooseneck and connects via an included pennant. 
  • Windseekers: Another type of staysail is the windseeker. This has a slim and tall profile and can stand on its own without connecting to your boat’s headstay. Instead, you attach your windseeker to your deck pad-eye via the tack. 
  • Code zero reacher: As a spinnaker variety, the code zero reacher has a look that makes it resemble a genoa more. With its unique profile, you can use this sail for achieving close range. It won’t puff out like a typical spinnaker, though. 
  • Drifter reacher: In the same vein as the code zero reacher is the drifter reacher. This genoa sail uses spinnaker fabric (that’s often laminated) so it can sail through lighter winds without difficulty.
  • Gennaker: The gennaker is named such because it’s a mix of a spinnaker and a genoa. You won’t get the kind of performance you do out of a spinnaker going downwind when sailing with a gennaker. That’s due to the speed of the gennaker, which isn’t stellar, mostly because it’s not nearly as big as your average spinnaker. In some cases, sailors will refer to the gennaker as the SpinDrifter, pole-less spinnaker, cruising chute, or cruising spinnaker. 

The Function


Jibs have numbers with a J in front of them, indicating the point of attachment for each jib. J1 can refer to the smallest or biggest point, with the latter much more common. Your jib may be a roller furling type. With this, you can connect the jib to your boat’s stay and then reef it with one hand. 

Another thing about the jib is it boosts your boat’s sail area and makes handling the vessel easier, boosting your speed. Think of this way: if you need more control of your boat’s bow, then you want to check your jib or headsail. If it’s the rear of the boat you need to control, such as the stern, that’s dependent on the mainsail. 


The mainsail function can go even deeper depending on the type you have on your sailboat. Here’s an overview of these:

  • Boom furling mainsail: The boom furling mainsail does not come with reef points. You can roll it up right into the boom, making it convenient to use.
  • Mast furling mainsail: Another mainsail type without reef points is the mast furling mainsail. This reduces control somewhat when sailing, even if the way you can roll it within the mast is super easy. 
  • Cruising mainsail: With a cruising mainsail, you enjoy more consistent performance. These sails don’t require a lot of maintenance, yet they should last you for years to come. You can either get a cruising mainsail with several reef points or just one. 
  • Full-batten cruising mainsail: While a cruising mainsail on its own is a good pick, if you’re interested in having more control over the shape of your sail, then you want a full-batten cruising mainsail. The length of the battens provides greater strength and reinforcement of your sailboat. This all leads to less flogging. 
  • Racing mainsail: With a name like a racing mainsail, if you’re expecting speed with this sail type, you’ve got it. You can use the reef points if you want, but it’s not mandatory. 
  • Square top racing mainsail: This is like your basic racing mainsail but with a top that’s squared off instead of triangular. Your speed and performance go up thanks to this redesign. 
  • High roach mainsail: The high roach mainsail combines the best qualities of the cruising and square top racing mainsails. You’ll find this sail option more often on multi-hulled boats and catamarans than sailboats. 

The Shape

Depending on the type of mainsail or headsail in question, the shape of your sail can differ somewhat. In this section, we’ll go over the sail shape for each of the types of sails we’ve discussed to this point:

  • Storm jib (a headsail for strong winds): Triangular, sort of like a staysail, but lower
  • Windseeker: Resembles a staysail, but more free-flying
  • Drifter reacher: Like a genoa sail but bigger
  • Storm trysail: Triangular but smaller than your average sail since it’s meant to replace the mainsail
  • Code zero reacher: Bigger and wider, like an upwind spinnaker but with luffing that’s tighter
  • Spinnaker: Wide, open, and free, much like a balloon
  • Genoa: Like a headsail, so it’s large and triangular, but also big enough that it outsizes the mainsail
  • Jib: A smaller type of foresail that’s triangular 
  • Bermuda: A triangular mainsail that’s higher on the boat

The Size

Which sail type is bigger, headsails or mainsails? 

Most of these sails, including the specialty types, are compared against what’s known as a foretriangle. Every boat has a foretriangle, which consists of the points of your headstay, foremast, and deck. These should be shaped like a triangle. 

If you’re not already familiar with your own sailboat’s foretriangle, then we recommend you go out to your boat and measure it out. Otherwise, the following information won’t make much sense to you.

Now that you’re more comfortable with spotting and using your foretriangle for measurements, let’s talk sizing. 


First, there’s your storm jib, which is technically a headsail, even if it’s not one you use all the time. From the height of your sailboat’s foretriangle, the storm jib should be 65 percent of that. It’s okay if it’s slightly less. 

The genoa is represented as a percentage of the foretriangle, as the genoa sail often is. It should consist of 122 to 155 percent of the foretriangle. As for your jib, it should encompass 100 percent of the foretriangle. 


Next, we’ve got the mainsails. Your storm trysail, much like the storm jib headsail, isn’t something you use all the time. Still, we’re sure you want to know the size of it anyway. The storm trysail is only 17.5 percent of your entire mainsail, making it a slim addition to your sailboat. 

Other Sails

How about some light air sails? Your free-flying windseeker should be 85 to 100 percent of the foretriangle. The drifter reacher doesn’t use the foretriangle formula, but rather it compares against the genoa, since it is a genoa sail itself. It should constitute 150 to 170 percent of your sailboat’s genoa.

The code zero reacher can be used for light air or upwind purposes, but either way, it should constitute 70 to 75 percent of your spinnaker. Yes, that’s right, the spinnaker, not the genoa. When riding downwind, the genoa sail itself should cover 125 to 155 percent of your foretriangle. Your jib should be 100 percent of that foretriangle. 

The Wind Speed

Finally, let’s discuss how your headsails and mainsails perform in various wind conditions. Wind speed is measured in knots and how far a vessel would travel per knot. When moving at one knot, your boat would go 1.15 statute miles. You can also convert wind knots to miles per hour or MPH, where a knot is the equivalent of 1.15078 MPH. We’ll use MPH going forward.


Let’s start with the headsails again. Your storm jib will travel at 45 knots or more, making it one of the fastest sails on your boat. To help you better understand how fast 45 knots is, it converts to 51.79 MPH. Not too shabby!

Your genoa doesn’t go that fast, only 30 knots, sometimes less. That’s 34.52 MPH or lower, so you’re not exactly dragging along the water, but you’re not going at a racing pace, either. Your jib can go as fast as the storm jib, give or take. It won’t ever exceed 45 knots like the storm jib will, so you’re limited to 51.79 MPH only. 


In the mainsails category, the storm trysail can also go over 45 knots, making it as speedy as the storm jib. Again, we’re taking over 50 MPH as a potential speed. Your other mainsail, the Bermuda, has a base wind speed of 30 knots or under. To reiterate, that’s about 34.52 MPH.

Other Sails

When riding a light air sail like the windseeker, don’t expect much of a speed boost at all. Some windseekers travel at zero knots while others will get up to six knots. That’s 6.91 MPH at most, so you’re moving at a very slow speed here.

The drifter reacher is slightly better, achieving up to 15 knots. You won’t get tremendous speed boosts necessarily, as the drifter reacher is recorded at going at 1 knot on the lower end of the spectrum. Sticking with that higher reading of 15 knots, the equivalent is 17.26 MPH, so now you’re getting somewhere. 

The code reacher moves at about the same speed as the drifter reacher, able to go a single knot higher at 16 knots. That barely changes its max speed to 18.41 MPH.

Now as we get to downwind sails, we’ve got the gennaker and spinnaker. The spinnaker can also reach up to 15 knots, or about 17.26 MPH. It requires a wind angle of 90 to 180 degrees. The gennaker has a knot range of one to 20 knots, with its max speed 23.02 MPH. You want to achieve a slightly sharper wind angle with your gennaker, between 75 and 165 degrees. 


The headsail and mainsail are two major features on your sailboat. While the headsail is at the front of the boat and the mainsail behind, there’s so much more to these two sail types than just that. They serve different purposes (improving control over the front or rear of the boat), come in different sizes (with the headsail bigger than the mainsail), and travel at different wind speeds.

Now, the next time someone asks you if you know the difference between your sailboat’s headsail and mainsail, you can say with certainty that you do!  


I am the owner of sailoradvice. I live in Birmingham, UK and love to sail with my wife and three boys throughout the year.

Recent Posts