Most cruising boats today have a sail plan consisting of at least three sails: A mainsail, a headsail, and a light-wind sail.
The Jib sail (along with its sister, the Genoa) is one of the most widely used headsails on modern sailboats in combination with a larger mainsail. It is very versatile and easy to use in different configurations throughout most weather conditions.
In this article, I want to explain the Jib in detail and talk a bit about how it works and how we rig and trim it to get the most performance out of the boat. I’ll also show you each part of the sail and its materials before explaining how it differs from other headsails like the Genoa.
Finally, I’ll finish with some tips on maintaining the sail properly to make sure it last as long as possible.
Well, shall we get started?
What is a Jib sail, and what do we use it for?
The Jib is a triangular sail that does not overlap the mainsail. It is typically between 100% and 115% of the foretriangle size and is commonly seen on modern vessels with fractional rigs.
The foretriangle is the triangular area formed by the mast, deck, and forestay. Learn more terms here.
Like other headsails, the Jib is usually rigged on a furling system attached to the forestay, making it easy to operate. The Jib can also be rigged with a self-tacking system, making upwind sailing easy for you, whether you want to cruise solo or with your friends.
How the Jib works on a sailboat
The Jib provides a sail area forward of the mast, allowing the boat to be steered and balanced effectively.
The curved shape of the sail creates a pressure differential. The outer, more convex side (leeward side) has a lower pressure than the inner, concave side (windward side). This pressure differential generates lift, which translates into forward propulsion, much like how an airplane wing produces lift.
How to rig a Jib
You can rig the Jib on either a furling system or directly to the forestay. Most modern sailing boats are equipped with a furling system, which is a long sleeve that runs from the top of the mast down to the bow and attaches to a drum on the bottom and a swivel on the top.
Take a closer look at this step-by-step process on how to rig the Jib to sail onto a furling system:
- Feed the Jib’s luff into the track on the furler’s sleeve with the top of the sail first and connect the head ring on the sail to the chackle on the swivel.
- Attach the Jib halyard to the swivel and hoist the sail up.
- When the sail is hoisted almost all the way to the top, you attach the sail’s tack to a shackle on the top of the drum.
- Put the halyard on a winch and winch it tight.
- Now you have to manually roll up the sail around the forestay and tie on the two sheets to the clew of the sail.
- Lead the two sheets on each side of the vessel’s side decks through the sheet cars, turn blocks, and back to the winches.
- Now that the sail is furled away, we need to tie the furling line onto the drum. You have to figure out how the furling line attaches, as it differs from system to system.
- Once the furler line is attached to the drum, ensure that it can wrap itself up freely.
- Pull the sail back out using one of your sheets and monitor that the furling line wraps on nicely.
- Leed the furling line through the blocks and funnels, through the jammer, and leave it next to the winch.
- Furl the sail away again using the furling line and ensure that the sheets run freely as you monitor your sail getting wrapped nicely around the forestay.
- Secure the furler line jammer and tidy up your two sheets. Make sure to secure the sheets around the winches.
So, you see now why most boats use furling systems? It is easy! Many larger sailboats even have electrical furlers, removing the need for the furling line.
How to use, reef, and trim a Jib
To use the Jib, you wrap the furler line around the winch, open the jammer, and pull on either of the sheets, depending on which tack you are sailing on. You should hold on to the furler line to prevent the sail from unfurling itself uncontrollably, especially in strong winds. Trying to catch it if it starts running can injure your hands, so be careful! I’m speaking from experience here; burned hands are “No bueno.”
You can now unfurl the entire sail or a part of it. Once the full sail, or the amount you desire, is out, adjust your car position and tighten the sheet.
How to reef a jib
You do the opposite as the above to reef the sail or furl it back in.
Ease off the working sheet, but keep it on the winch. At the same time, pull in on the furler line either manually or on the winch. Remember to move the cars forward and re-tighten the sheet if you are reefing away only a part of the Jib.
How to trim a jib
Adjusting the sheet cars and sheet tension is important to obtain an optimal sail shape in the Jib. Finding this balance is what we call sail trim. I’m not going too deep into sail trim here, as it is a topic for itself, which will require a separate article,.
But here is a rule of thumb:
You want the leech and foot of the sail to form an even “U” shape on any point of sail. When sailing upwind, you usually move the car aft. When bearing off the wind, you move the car forward.
The goal is to apply even tension on both the foot and the leech. When you reef the sail, you’ll also want to move the car forward to adjust for the reduced sail area. Sailing downwind doesn’t require the same fine-tuning as upwind sailing.
Four tips for sailing upwind:
- Winch up the jib sheet until the leech stops fluttering and the foot has a nice, even “U” shape.
- You must move the sheet car forward if the foot is tight and the leech flutters.
- Move the sheet cars aft if the leech is tight and the foot flutters.
- If the wind increases and the boat starts to heel excessively, you can either ease off the sheet or adjust your course more head to wind.
You should play around and experiment with sail trim, as every boat behaves differently. Trimming sails is an art that takes time to master. Staysails, Jibs, and Genoas are trimmed the same way, but the car positions will be different due to their size and shape differences. Once you learn how to trim a Jib, you’ll be able to trim any headail and even a storm jib or a spinnaker.
Sailing with more than one Jib
Sailing with multiple jib sails can be beneficial on longer downwind passages. Most furling systems have two tracks, allowing you to have two Jibs on the same furler, making this setup easy to reef. You can do the same with Yankees and Genoas, depending on what you have available in your boat.
Some sailboats have two or more forestays, allowing them to have two individually furled Jibs. This is usually called a cutter rig. Most Cutter rigs, however, use a Staysail on the inner forestay and a Yankee sail on the outer, but this versatile rig allows you to experiment with many setups.
Exploring the different parts of the Jib
Head: The head is the top corner of the Jib. It typically has a ring in the top corner that attaches to the Jib halyard or the top swivel for furling systems.
Leech: The leech is the aft part of the rib, located between the clew and head.
Luff: A Jib’s luff is the front part between the tack and head. Jibs can be equipped with luff foam to help maintain their shape when partially reefed on a furler.
Clew: The clew is the aft lower corner of the jib where the sheets are attached.
Tack: The tack is the lower, forward corner of the Jib. The tack is connected to a furler drum on the forestay on most sailboats. Vessels using traditional hank-on headsails connect the tack to a fixed point on the bow.
Foot: The foot of the Jib is the bottom portion of the sail between the clew and the tack.
Telltales: Telltales are small ropes, bands, or flags attached to the front of the Jib’s leech to help us understand how the wind affects the sail and allow us to fine-tune the trim for optimal performance.
Commonly used materials for the Jib
The most common material used for Jib’s today is Dacron woven polyester, followed by CDX laminate due to the relatively affordable price. Continuing up the range, we find woven hybrids like Hydranet, Vectran, Radian, and other brands.
Then, we have advanced laminates with Aramids, carbon, kevlar, and more exotic materials. At the top of the spectrum, we find the latest technology in DFi membrane sails like Elvstrøms EPEX or North Sails 3Di, which comes at a premium price tag.
These days, however, modern technology has given us warp-oriented woven cloth, which is becoming a popular option due to its increased ability to keep shape over time without stretching as much as traditionally cross-cut dacron sails. ProRadial, made by Contender and Dimension Polyant, is a good example.
North Sails has an excellent article that goes in-depth on sail materials.
The difference between a Jib and a Genoa
The difference between a Jib and a Genoa is that the Jib is a headsail that does not overlap the mainsail, while the larger Genoa is designed to overlap the mainsail. While the smaller Jib is excellent at pointing upwind and easier to handle, the larger Genoa excels on any points of sail with the wind behind the beam.
Genoas are usually larger than 115% of the foretriangle, with sizes ranging from 120% to 150%. They are often used on yachts with masthead rigs and smaller mainsails but are also common on fractional rigs.
How to Maintain and Care for Your Jib Sail
Good maintenance and care of your Jib will ensure optimal performance and minimize wear and tear. Check out these tips on how to maintain and protect your Jib:
- Rinse the Jib with fresh water regularly and leave it up to dry before packing it away. Proper drying will prevent moisture and mildew.
- Give the sail a service once a year. Check for any damaged seams and repair them if necessary. If there are any chafing marks, reinforce the sail with patches on chafe points and add shafe guards to the equipment it rubs against.
- Protect the sail from UV rays by keeping it packed away when not in use. A furling Jib can be protected by adding a UV strip to the foot and leech.
I also wrote an article on how to make sails last longer.
We have talked a lot about the Jib’s features and how it works in this article. I recommend you to head out and set sail to get some experience and play around with your sails. If you don’t have a boat, chat around in your nearest marina; someone will for sure bring you along for a sail. I know I would.
Remember to experiment with sail trim and practice tacking and maneuvering the vessel with the sail on both the port and starboard sides.
If you still have questions, check out the frequently asked questions section below or drop a comment in the comment field. I’ll be more than happy to answer any of your questions!
PS: Explore more sails in my easy guide to different types of sails here.
FAQ – The Jib Sail Explained
When to use a jib sail?
The Jib is an excellent sail for most conditions, especially when cruising at any angle towards the wind. The Jib has a benefit over the Genoa in strong winds as it is easier to handle, and its smaller size makes it more effective than a reefed Genoa when sailing to windward.
Can you sail with just the Jib?
It is possible to sail with just the Jib alone, and it works exceptionally well downwind on deep angles where the mainsail usually would have blocked off the wind.
Can you sail upwind with just the jib?
It is possible to sail upwind with just the Jib, but most sailboat owners prefer to balance their boats by flying their mainsail combined with theiJib when sailing to windward.
What is the difference between a Genoa and a Jib?
The Genoa is different from a Jib sail as it is larger and overlaps the mainsail, whereas the Jib is smaller and does not overlap the mainsail.