1990 200 Candia Deck Boat Outdrive

[krogers385]

I have a 1990 200 Candia Deck boat that stays in the water at my dock. I have noticed recently that if do not use it for 3 or 4 days, the outdrive will be lowered back into the water. At first, I thought I had absentmindedly forgotten to raise it but weekend before last I made sure I raised it. When I went back on Friday it was fully lowered into the water. What can cause this and what is the fix? The water is shallow enough when the drive is down to endanger the prop to banging on the river bottom with the wave action.