My first sailboat was a Huntre 23, it came with a trailer with the extending tongue to allow the trailer to get into deeper water for the draft of the keef with out flooding the car. Before my first attempt at launching the boat, so I could look like a pro, I practiced stepping the mast and setting the boom several times. I had it down pat.On a busy Saturday, we took my fine craft to a boat ramp on north Tampa Bay. I stepped the mast and set the boom as people watched, answering questions of several by-standers. Now ready to launch, I backed the boat onto the ramp, but then remembered that I hadn't extended the tongue. I lowered the landing gear on the front of the trailer, told my wife to pull the pin as I rocked the car back and forth, and replace the pin as the next hohe in the tongue came into view. But I forgot I was still on the ramp!!I rocked the car back and forth, the pin came out as it was supposed to. Then the boat rapidly rand down the ramp towards the water. I jumpped out of the car, ran towards my run-away boat, and because I had not placed the car in park, it began rolling forward. My wife quickly ran to the car and stopped it. Stamding knee deep in water, I reatteached the tongue, hooked it back into the car and tried to launch the boat. Only to find that with the out-going tide, it was now too shallow to get the boat off the trailer.Red-faced I unstepped the mast went home and tried again the next day at another ramp, this time successfuly, and with much more humility.