Both the jib and the genoa can also accurately be referred to as the headsail because it is at the head (bow (front)) of the sailboat.
A jib is when the foot of the headsail is shorter than the distance from the forestay to the mast. A genoa is when the foot of the headsail is longer than the distance from the forestay to the mast. As with the mainsail, you can use the headsails at all points of sail from close haul (usually about 30-40 degrees off from where the wind is coming from) to a downwind run. headsails are also referred to by number. A number one headsail would mean the largest genoa on board the vessel. You might also hear a number like 130 headsail which means that the foot extends 30% past the mast to forestay distance.
So as you learn to sail, you’ll find the headsail is relatively easy to operate. The main controls are the two jib sheets. One on each side of the boat. The jib sheet that is on the leeward (downwind) side of the boat is referred to as the working jib because it is tensioned up. The windward jib sheet is referred to as the lazy jib sheet because it is not being used and is left loose. Many new sailors just learning to sail try to pull the lazy sheet tight, partly because it seems unnatural to have a line on a sailboat that is slack. The best position for a lazy sheet to be in is slack but ready to be tensioned by being wrapped around the winch in a clockwise direction.
Another line attached to the headsail is the halyard. The halyard is the line used solely for hoisting and lowering the headsail. Even if the headsail is a roller furling headsail, it will still have a halyard to hoist it up.
One function of the headsail, which is not obvious to novices as they learn to sail, is that the headsail feeds extra wind to the back side (downwind side) of the mainsail. This provides extra lift function from the increased velocity of the wind being diverted by the headsail. This is explained more in our article which explains how sails actually work.
The set of the headsail should follow the set of the mainsail. As you learn to sail more and more you’ll be able to expertly set the headsail according to the telltales mounted close to the leading edge of the headsail. However for now just set it according to how far away from the wind direction you are headed and according to this golden rule: Let the working headsail sheet out until you see the leading edge of the sail begin to fold in on itself then tighten the sheet up a little.
This is actually a fairly accurate way of doing it and you’ll notice that the more away from the wind you steer, the more you will need to let out the headsail sheet. And in doing so, you’ll notice that it is mimicking the set of the mainsail discussed in another article in this series.
On a close haul which is when the sailboat is steering 30-40 degrees off from the direction of the wind, the best position of the headsail is cranked in tight so that the sail is about 4-6 inches (10 -15 cm) away from the spreader bars on the mast. To some this may seem overly tight and it takes a lot of strength to get the sail in this tight. But alas, this is what will be required to stop the leading edge from folding in on itself.
Headsails vary in size and are hoisted according to the wind conditions. As a general rule, you’d use a 150 genoa in winds up to about 10 knots. A 130 genoa to about 12 knots. A 110 genoa to about 15 knots. A 90 Jib at 20 knots. A 70 jib at 25 knots. A 50 jib at 30 knots. And a storm jib sail anything above 30 knots.
Headsails are either of roller furling type which are becoming more common, or are hanked on by clips to the forestay and raised and lowered each time. Roller furling headsails can not have horizontal battens which help control the airfoil shape of the sail. However some newer design roller furling headsails incorporate vertical battens which aids the shape.
Raise and lower hanked on headsails are reefed by replacing the sail out with a smaller sail this takes time and some serious effort. Roller furling headsails are simply wound up to reduce the size of the sail. This however does create a large leading edge to the headsail which decreases the effectiveness of the sail due to spoiled wind at the leading edge.
We’ll discuss the physics of how the headsail provides forward motion to the sailboat in a follow on article.