Late 80's I had a 15' hydrostream speedboat that I towed with an 83 GT mustang 5spd. The ramp was steep and full of algae, back down the ramp, set the emergency brake and put it in 1st. gear. Start cranking, the boat's 1/2 up the trailer when the car starts sliding back. I jump off try to open passenger door but it's locked, car still sliding run to driver's get in start car now rear wheels are slightly in. 1st spinning wheels, still sliding, pop 2nd. spinning wheels not a thing I could do 4" over the roof. The funny thing was after I knew it was hopeless I turned off the car got out what else could I do, turn around and with nothing on in the car the parking lights with the help of salt water that completed the circuit were glowing a nice amber visible thru the beautiful green colored NY water. Every thing electric in the car was replaced after that and it ran better than ever.