Hook in mainsail

[Guest Chris5876]

In light wind (4-5mph), my J/22 Quantum mainsail folds in the middle to create a “hook” causing the wind not to attach to the sail. We took the top batten out and have to hold the boom up a bit to get a smooth aerodynamic shape. What setting in the traveler, mainsheet, or something else is causing that?

[cdoyle]

Put the batten back in. Pull the traveler all the way to weather and then ease the sheet until the boom is on the centerline. Make sure the vang is eased. 
 

Also, make sure your battens are inserted with the tapered ends forward. 
 

if the above doesn’t work, it may be time for a new sail.  
 

it would be good if you could take a picture and post it here. 

[TyeDyedGary]

Your leach line may be pulled to tight for the wind condition. otherwise what cdoyle said.

[GER1640]

Since the class rules 2021 the length of the lowest main sail batten has been changed form 686 mm to 915 mm. With this change the lowest batten doesn't end at the same line as the upper threee battens and that helps to reduce the hook effect on older sails.