I have equipped an Elan plastic boat (16 ft)with 1975. Mercury D500 outboard, which runs fine, but when running fast, gives two strong jets of water, just over the sides of the shaft, diagonnaly upwards. Also there is some water entering the engine well on the stern, just over the steering cylinder. The jets come between the two lift cylinders. The jets are stronger, the faster boat moves through the water. Ventilation plate is appr. 1 in lower than the transom bottom, and vertical trim seems to be in order. The boats top speed is some 24-25 mph. Please, advice me what to do.
