I recently acquired a Catalina 30 Tall Rig, which is great ! We are having some trouble with our depth meter. It seems that when the engine is running the display shows unusually high readings for depth and when the engine is off and we are under sail, the readings seem closer to the depths shown on my charts for a particular area we are navigating in. We have a Signet depth meter. Does anyone have a trouble shooting manual or suggestions for us on how to correct the problem ?