[willy]

Came up with an idea for boat ramps that have a hose a couple of years ago.
Put one of those fixed sprinkler heads with a pretty good wide pattern on the ground under the boat and trailer, with hose attached of course.
Have a thirty some foot length of para cord, attached to the other side of the sprinkler and a weight on the other end of the para cord. Toss the length of the trailer on the ground and just ull it along underneath pausing as long as you want to flush the the whole underside of the trailer and boat.
Have a handle on the sprinkler and an adjustable spray pattern and use it for the rest of the boat.