DEPTH FINDER PROBLEMS
~ Captain Paul's response to: ~ Mike ~
The inability to read depths at high speeds is a common problem with some depth finders. This is usually caused by the slipstream generating bubbles which react with and deflect the transducer signals. A flat boat with various ridges running the length of the bottom usually causes more of the interference.
For high speeds the transducer has to be aimed more forward when under way at increased speeds. If the transducer is aimed directly downward, it is possible that the vessel will pass away from the reflected signal before the signals can reach back to the transducer. It may work in shallow water, say under 10 feet, but deeper water requires the signal to travel farther and the transducer may not then be in a position to always receive the signal. A speed of 35 mph the vessel would have traveled about 51 feet in a second. At that speed the transducer may not be able to read the return signal.
The blacking of the screen usually comes from the unit being in a heated environment such as in direct sun light for a period of time or a short has occurred in the display screen. Either way, if the unit is still under warranty, I would call Humminbird support at 1-800-633-1468 and get an opinion from them. I would insist that they take a look at the unit.
The cost of their bench fee, just to look at the unit if our of warranty, will nearly be the same as a new unit. If it is still in warranty, send it back NOW.
~ Captain Paul ~