watertight enclosure surrounding the vehicle on all sides including bottom a closure means preferably a heavy duty zipper 6 extending on two sides 5 and rear 7 allows when opened access to the interior of the enclosure an overlapping strip of sheeting material 8 covers the zipper 6 so that water entry is not possible located within the front part of the enclosure 9 a ventilating fan 10 is mounted on a bracket 11 and situated so that its air intake port faces an opening in the enclosure sheeting having a fitting 12 connecting to a flexible ducting 13 leading to a filter housing 14 referring to fig6 and 7 when the motor 15 driving the impeller of ventilating fan 10 is electrically energized air is drawn in through a screen 16 enters the filter housing 14 flows through filter 17 duct 13 and is discharged by the fan 10 into the interior of the enclosure causing it to become inflated once inflated and an equilibrium condition is attained the airflow is of such magnitude that it equals the leakage through small openings in the enclosure and through the zipper 6 which is designed to leak an amount of air sufficient to ventilate the enclosure the.