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  Heads'l Dimensions

Heads'l Dimensions

12/09/14

What exactly does a sailor mean when he says "I have a 135% Genoa"? How is that number calculated and what does it mean? Most sailors understand that a larger percentage corresponds to a larger heads'l, but many don't know how that number gets calculated. 

When ordering a new heads'l, it's a good idea to know what size you currently have so you can either order the same size, or adjust the size up or down to reflect the experience you have with your current sails and prevailing weather conditions in your area.

Headsail size is calculated from two measurements, one on your boat and one on the sail.

The first is the "J" dimension. This is the distance from the mast to the bottom of the forestay at the stem fitting when measured along a line perpendicular to the mast. Since you can't measure through the cabin, measuring from the stem to the mast step is close enough.

 
The second dimension is the "Luff Perpendicular" or "LP". This is the distance of the headsail clew from it's luff when measured along a line perpendicular to the luff. Rather than trying to establish a right angle at the luff, you can simply measure the shortest path between the clew and the luff.

 

The size of your headsail expressed as a percentage is simply LP divided by the J.

 

For example, if you measured the "LP" at 11' and the "J" of your boat is 10', then: 11/10 = 1.1 or 110%.

 

On the same boat a sail with a 15' LP would be a 150%, (15/10 = 1.5 or 150%).

For heads'l measurements:

Use the dimensions shown in pink on the diagram at left.

 

Note that the "LP" is perpendicular to the luff of the sail, and the "J" measurement extends to a point directly above where the forestay attaches to the stem fitting.

 

The "J" measurement can be measured as shown, or you can call our staff as we have that figure for most Catalinas.

 

Now that you can determine what size headsails you have, here are some descriptions that might help you choose your new headsail.

The 110% is a common size headsail suitable for a wide range of wind and sea conditions. It provides adequate power in a moderate breeze and takes a good bit of wind without being overpowered. Adding inboard sheeting for a 110% jib will almost certainly improve windward performance. 

 

A 135% genoa may be more popular with sailors who sail primarily in moderate conditions. When combined with a roller furling system, the 135% genoa can be effectively reefed to something around a 110% jib when the wind pipes up and it will still maintain excellent sail shape. If you must reef deeper than that, the 135% genoa will still be an effective heads'l, though the shape may not be optimal.

 

The 150% genoa is usually used for very light air where its large sail area and easily flown light cloth can keep you moving in a zephyr. The 150% genoa should not be reefed too deeply, as its light cloth weight (essential for light air performance) makes it vulnerable to being blown out in heavy air. If the wind pipes up strong, the 150% genoa should be rolled up completely to preserve its shape.

 

Storm sails and heavy weather sails are typically in the 50% to 75% range. These are very sturdy specialized headsails that usually have a short luff as well. A storm sail might have a 50% luff and a 50% LP/J configuration. They are made for both hank on rigs and furling rig versions that can be hoisted over a furled heads’l. It is more common to have a 75% heavy weather sail aboard but if your are heading to Tahiti, a smaller storm jib is definitely in order.

 

 

 

 

 

 

 

 



Products
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C-38 Genoa 135%
Furling Ullman Offshore


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C-387 Genoa 135%
Furling Offshore by Ullman


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C-400 Genoa 135% Furling Ullman Offshore

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C-350 Jib 100%
Furling Ullman Offshore


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C-470 Main In Boom Furling Ullman Offshore

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C-380 Jib 110%
Furling Offshore by Ullman


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C-470 Std Rig Genoa 135%
Furling Offshore by Ullman


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C-350 Genoa 135%
Furling Ullman Offshore


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C-36 Std Rig Genoa 135%
Furling Ullman Offshore


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C-36 Tall Rig Genoa 135%
Furling Ullman Offshore


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C-380 Genoa 135%
Furling Offshore by Ullman


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C-42 Genoa 135%
Furling Ullman Offshore


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C-470 Tall Rig Genoa 135%
Furling Offshore by Ullman


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C-22 Jib 110% Furling Offshore by Ullman

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C-25 Std Rig Jib 110%
Furling Offshore by Ullman


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C-25 Tall Rig Jib 110% Furling Offshore by Ullman

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C-28 Std Jib 110% Furling Offshore by Ullman

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C-320 Jib 110% Furling Offshore Ullman

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C-34 Std Rig Jib 110%
Furling Ullman Offshore


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C-34 Tall Rig Jib 110%
Furling Ullman Offshore


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C-350 Jib 110%
Furling Ullman Offshore


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C-36 Std Rig Jib 110%
Furling Ullman Offshore


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C-36 Tall Rig Jib 110%
Furling Ullman Offshore


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C-387 Jib 110%
Furling Offshore by Ullman


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C-42 Jib 110%
Furling Ullman Offshore


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C-470 Tall Rig Jib 110%
Furling Offshore by Ullman


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C-25 Tall Rig Genoa
150% Furling Offshore by Ullman


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C-250 110% Furling Jib Ullman Offshore

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C-250 135% Furling Genoa Ullman Offshore

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C-250 150% Furling Genoa Ullman Offshore

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C-27 Std Rig Genoa
135% Furling Offshore by Ullman


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C-27 Std Rig Genoa
150% Furling Offshore by Ullman


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C-27 Std Rig Jib
110% Furling Offshore by Ullman


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C-27 Tall Rig Genoa
135% Furling Offshore by Ullman


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C-27 Tall Rig Genoa
150% Furling Offshore by Ullman


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C-27 Tall Rig Jib
110% Furling Offshore by Ullman


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C-270 Std Rig Genoa
135% Furling Offshore by Ullman


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C-28 Std Rig Genoa
135% Furling Offshore by Ullman


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C-28 Std Rig Genoa
150% Furling Offshore by Ullman


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C-28 Tall Rig Genoa
135% Furling Offshore by Ullman


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C-28 Tall Rig Genoa
150% Furling Offshore by Ullman


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C-28 Tall Rig Jib
110% Furling Offshore by Ullman


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C-30 Std Rig Genoa
135% Furling Offshore by Ullman


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C-30 Std Rig Genoa
150% Furling Offshore by Ullman


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C-30 Std Rig Jib
110% Furling Offshore by Ullman


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C-30 Tall Rig Genoa
135% Furling Offshore by Ullman


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C-30 Tall Rig Genoa
150% Furling Offshore by Ullman


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C-30 Tall Rig Jib
110% Furling Offshore by Ullman


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C-42 Genoa 140% Furling Offshore Ullman

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CP-14.2 Furling Jib,
Offshore by Ullman


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CP-16 Furling Jib, Offshore by Ullman

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CP-16.5 Furling Jib Offshore by Ullman

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CP-16.5 Furling Jib w/ UV Cover Offshore by Ullman

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CP-18 110% Furling Offshore by Ullman

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CP-18 135% Furling Genoa Offshore by Ullman

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CP-18 150% Furling Offshore by Ullman

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CP-22 Std Rig Jib 110% Furling
Offshore by Ullman


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CP-22 Tall Rig Jib 110%
Furling Offshore by Ullman


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CP-22 Std Rig Genoa 135%
Furling Offshore by Ullman


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CP-22 Tall Rig Genoa 135%
Furling Offshore by Ullman


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CP-22 Std Rig Genoa 150%
Furling Offshore by Ullman


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CP-22 Tall Rig Genoa 150%
Furling Offshore by Ullman


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CP-26 110% Furling Jib Offshore by Ullman

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CP-26 135% Furling Genoa Offshore by Ullman

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CP-26 150% Furling Genoa Offshore by Ullman

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C-15 Hank On Jib Offshore by Ullman

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C-22 Genoa 135% Hank On Offshore by Ullman

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C-22 Genoa 150% Hank On Offshore by Ullman

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C-22 Jib 110% Hank On Offshore by Ullman

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C-22 Storm Jib 50%
Hank On Offshore By Ullman


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C-22 Storm Jib 75% Hank On Offshore By Ullman

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C-25 Std Rig Genoa 135% Hank On Offshore by Ullman

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C-25 Std Rig Storm Jib 50%
Hank On Offshore by Ullman


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C-25 Std Rig Genoa 150% Hank On Offshore by Ullman

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C-25 Std Rig Jib 110% Hank On Offshore by Ullman

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C-25 Std Rig Storm Jib 75% Hank On By Ullman

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C-25 Tall Rig Genoa 135% Hank On Offshore by Ullman

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C-25 Tall Rig Genoa 150% Hank On Offshore by Ullman

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C-25 Tall Rig Jib 110% Hank On Offshore by Ullman

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C-25 Tall Rig Storm Jib 75% Hank On By Ullman

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C-27 Std Rig Genoa
150% Hank On Offshore by Ullman


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C-27 Std Rig Jib
110% Hank On Offshore by Ullman


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C-27 Tall Rig Genoa
150% Hank On Offshore by Ullman


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C-27 Tall Rig Jib
110% Hank On Offshore by Ullman


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C-30 Std Rig Genoa
150% Hank On Offshore by Ullman


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C-30 Std Rig Jib
110% Hank On Offshore by Ullman


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C-30 Tall Rig Genoa
150% Hank On Offshore by Ullman


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C-30 Tall Rig Jib
110% Hank On Offshore by Ullman


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C-34 Std Rig Genoa 150%
Hank On Ullman Offshore


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C-34 Std Rig Jib 110%
Hank On Ullman Offshore


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C-34 Tall Rig Genoa 150%
Hank On Ullman Offshore


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C-34 Tall Rig Jib 110%
Hank On Ullman Offshore


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C-350 Jib 110%
Hank On By Ullman


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C-36 Std Rig Genoa 150%
Hank On Ullman Offshore


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C-36 Std Rig Jib 110%
Hank On Ullman Offshore


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C-36 Tall Rig Genoa 150%
Hank On Ullman Offshore


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C-36 Tall Rig Jib 110%
Hank On Ullman Offshore


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C-380 Genoa 150%
Hank On Offshore by Ullman


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CP-14.2 Hank On Jib,
Offshore by Ullman


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CP-16 Hank On Jib Offshore by Ullman

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CP-16.5 Hank on Jib Offshore by Ullman

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CP-18 150% Hank On Genoa Offshore by Ullman

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CP-18 Hank On Genoa 135% Offshore by Ullman

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CP-18 Hank on Jib Offshore by Ullman

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CP-22 Std Rig Jib 110% Hank On
Offshore by Ullman


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CP-22 Tall Rig Jib 110% Hank On
Offshore by Ullman


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C-22 Genoa 150% Furling Offshore by Ullman

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C-25 Std Rig Genoa 150% Furling Offshore by Ullman

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C-320 Genoa 150%
Furling Offshore Ullman


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C-34 Std Rig Genoa 150%
Furling Ullman Offshore


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C-34 Tall Rig Genoa 150%
Furling Ullman Offshore


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C-36 Std Rig Genoa 150%
Furling Ullman Offshore


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C-36 Tall Rig Genoa 150%
Furling Ullman Offshore


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C-380 Genoa 150%
Furling Offshore by Ullman


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C-387 Genoa 150%
Furling Offshore by Ullman


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C-400 Genoa 150% Furling Ullman Offshore

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C-42 Genoa 150%
Furling Ullman Offshore


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C-470 Tall Rig Genoa 150%
Furling Offshore by Ullman


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C-22 Genoa 135% Furling Offshore by Ullman

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C-25 Tall Rig Genoa 135% Furling Offshore by Ullman

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C-309 Genoa 135% Furling Ullman Offshore

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C-310 Genoa 135%
Furling Offshore by Ullman


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C-320 Genoa 135% Furling Offshore Ullman

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C-34 Std Rig Genoa 135%
Furling Ullman Offshore


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C-34 Tall Rig Genoa 135%
Furling Ullman Offshore


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C-25 Std Rig Genoa 135% Furling Offshore by Ullman

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CP-22 Std Rig Racing Genoa 155%
Furling Offshore by Ullman