We launch over the side at Knott End simply 'cos you have to on many ocasions. Last weekend was a very small neap. On a spring when we may have 10.5 to 11m high water the tide over the ramp produces a mass of waves from around 2 hours before hw which can make launching conventionally nigh on impossible. At the very least it can cause a lot of hull damage! At this state of tide it is easier to launch the bigger boat over the side than th C-rider off its conventional trailer in the conventional way.
My background has been launching fast fishing boats off exposed beaches for years. We are never able to float boats on from these beaches-more damage is caused by boats lifting on a wave and then dropping on a sharp bit of trailer than by taking it virtually dry off the beach. My club has 5 tractors all with electric winches on the back but the manual trailer winch is ok. You winch as, Johno says, the trailer underneath the boat to a certain extent. We handle boats up to 7m with no probs.