If you do your home work understand weather charts and are sensible you should have no problems heading out that far, have been out to browns many of times chasing tuna in winter and have had no problems, but must stress have studied the weather charts in great detail and ticked all the boxes and doubled checked everything right up to the last moment.I Know of a 5.6 mt boat that heads out to Heatons ,thats 3 times the distance of the shelf. Boats are not designed to sink or capsize, its the person behind the wheel just like cars are not designed to wrap themselves around telegraph poles