I`m not sure if I can help or not but I`ll give it a try.I `ve had my j30 for 5 yrs.now & the second year i had it I had a similar problem. I noticed an excessive rake aft in the mast. This created lots of weatherhelm.So I readjusted the fore stay and shrouds so there is just about 6 or 8 in. of rake.The fore stay appears maxed, the mast is back against the opening in deck. the upper shrouds are approx 40 on guage & lowers are approx . the same.The shrouds are never loose on leward side.My helm is very comfortable to weather now, but off the wind it can still be excessive. this is the nature of the beast.Sail trim is very important in reducing helm as well. It is not hard to loose control in close quarters in gusty conditions.How long have you been sailing the j30? I also balance my rudder, but I don`t think this is legal if racing one design. It did help reduce helm off the wind but did not eliminate it.
Good luck,
Clive J
