J is for Jib


Firstly and simply, a jib is the triangular sail on the front (the bow) of a sailing vessel. The bottom corner, or tack, is fastened at the bow or the bowsprit if the vessel has one. The function of the jib is not just for jaunty appearance or to provide more sail area, but to smooth the flow of air on the back side of the mainsail. Again, not to get too complicated about it, when a sailboat is going against the wind, it’s the effect of the airflow on the back side of the mainsail that draws the boat through the water.

air flow 1

In the figure, the flow to the right of the sail causes a low pressure area. Think of being in the shower with a shower curtain. When you turn the water on, the flow of water causes a flow of air on the inside of the shower curtain. That airflow draws the curtain in on you. It’s maddening, especially if you’re in a hurry. So, in the figure above, the flow on the left side of the said is pushing, but the flow to the right side is pulling, just like that shower curtain. Now you put a jib on the boat.

air flow 2

The jib smoothes the flow of air on the backside of the sail, making it much more efficient. Jibs are really cool that way. It increases the power of the sails but also enables the boat to point a little further into the wind.

There are, as you might imagine, many kinds of jibs, especially on classic sailing ships. Working from the inside out, there’s the staysail (still a jib), the inner jib, the outer jib and the flying jib.


In addition there are storm jibs (much smaller for strong winds), Genoa jibs (usually on smaller vessels that have fore-and-aft rigs. Genoas can be great huge things that overlap the main sail, very efficient and wonderful in light air), and working jibs.

In the olden days of sail there were many more types. Remember the phrase ‘Arrh, Captain, I don’t like the cut of his jib’ from swashbuckling movies? In those days of sail, the shape of jibs of all types in the royal navy were very clearly defined, manufactured by military specification if you will. Pirates, not being limited by military specifications (‘they’re more like guidelines really.’) and/or orders, were free to experiment with different cuts of sails to increase their efficiency and did so frequently. So when a merchant ship was being approached by another ship at sea (ostensibly benign) it was a good idea to look at the cut of their sails to have an idea if the other vessel was play-acting and they might well be attacked by pirates.




11 thoughts on “J is for Jib

    • I’m so glad you liked it. I struggle a bit to keep the explanations not too long, not too short, but just right. We’ll see how successful I am at the finish line! Thanks.

  1. Thank you once again for extending my knowledge of sailing so I can try to keep up with the rest of the family. Geoff took our son out for a lovely sail in the Laser yesterday while my daughter and I headed off in the kayak. Mister operated the tiller, which I think must have drained his powers of concentration as he hasn’t listened ever since.

    • You really need to get on a sailboat. I know the terms sound all salty and arrrgh, but conceptually sailing is really simple and I can’t imagine anyone not enjoying it. You just have to be allowed to make your own misteaks (ahem). Just do them on a relatively calm day, for as I once heard ‘lessons earned are better than lessons learned if the cost ain’t too dear’.

      • I do love love sailing and get out occasionally. UNfortunately, wind has been rather uncooperative…either too strong or non-existent. We’re hoping for better conditions over here on Broken Bay rather than Palm Beach where it was more sheltered.

  2. I am enjoying this. My husband is going to get a boat next year, I am going to be so informed:)
    Good luck with the rest of the A-Z!!

    • Thank you, and thank you for reading. I’m going to be looking for a new boat soon myself, so reviewing all this stuff is good for me too. My brain is too full of cobwebs so it’s a good exercise. Thanks.

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