And a ten foot drop-off. While launching and retrieving at high tide are easy, a minus tide usually means having to lift the boat on and off the trailer. You will not be able to float the boat off or on the trailer unless you drop the wheels off the edge. With Kayaks and small inflatables, this is not a problem, but with inflatables larger than fourteen feet, and during times with big swells, this is extremely difficult. The most common method for dealing with this involves rounding up as many divers as you can, and lifting the boat onto the trailer, but I have seen several creative alternatives.
Some people just back the trailer off the end of the ramp.
Doing this without a 4x4 is a slippery task, due to the thick mat of algae that is growing on the ramp. If the surge is strong enough, water will get into your brakes, and without a fresh water rinse afterwards, will eventually wreak expensive havoc with them. One guy I met used a rental car to deal with this problem, but in order to keep my brakes and wheel bearings out of the salt water, I detach the trailer, and use a winch mounted on the back of my truck, with the hook attached to the front of the trailer. This allows us to push the trailer wheels off the end and still be able to retrieve it without having to do a search and salvage dive. Some people have rigged floats to their trailers to keep them afloat when they are pushed off the edge.