We go out on Lake Ontario all the time.. Been out there a few times in 6-8' waves.. The best time is just after a big wind when the waves are still large but the wind is 10-15knots.. Lots of fun surfing. You have to make sure that your boat is solid, and if you do a lake crossing (which we do occasionally) that you go with other people. Its always a good idea to bring a cell phone or vhf, and tell people that you are going out..so that they know to look for you if you don't come back.