J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment prebend

It will start depowering the main earlier and will impact light air sailing. Most sailmakers have their designs setup for the optimal sail shape starting with the rig in the correct position. With 15 kt trade winds shouldn't even need to start the backstay tension.

Since you need to pull the mast to adjust the base position, if you are not doing racing, you can wait until a convenient time when you pull the stick. Otherwise if you are racing, you are taking a performance hit.