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Can you guys help me out with using my sonar in manual mode?
Here is the scenario: I usually fish deep water for tuna so this is my typical situation
Fishing the floaters out of venice in 1000' of water, take me through the steps
Put the unit in 50khtz mode, then turn the power up to 100%. Then adjust the gain until you get rid of most of the noise (snow), but still hold bottom. You will need 1000 watts or better in 1000' of saltwater.
Quick and dirty Definitions: Range = The range of the water depth displayed on the screen. The top of the screen represents the top of the water (0'), your range setting tells the display what depth to display at the bottom of the screen. Usually, the auto setting works fine. If your in 100' of water, but you only care about the first 10' of water, set the rage to 10'. Your display will show the water column from 0 to 10' on the screen. The sounder will still be looking at (sending sound waves to the bottom) and displaying the proper depth (100' in this case), but you won't see it.
Gain = Sets the sensitivity to the transducer when listening for the return. Think of this like the squelch on a VHF radio. If you turn the squelch all the way down, you will hear all the noise the receiver is picking up (fuzzy sound). Turn the squelch up, and you will block out most of the background noise. Same goes for the gain. Turn it up and you will see all the background noise (snow or fuzzy stuff) on the display. Turn the gain down, and you will block out the fuzzy stuff. BUT, just like on a VHF, if you turn the squelch to high, you will also block out weak signals of a friends boat far away. In the case of gain, you could possibly block out a return from a small bait fish.
Power = The amount of power output by the transducer in the form of sound. This is the volume setting. The further you need the sound to go (the deeper the water in other words), the louder the volume (or power in this case) needs to be. So the deeper the water, the higher the power.
Those are the very basics. Of course you can play with these in combination for better results. For example, turn the power down, but turn the gain up. In this case you would be sending out a weaker sound signal(with the power turned down), but listening harder for the return (with a higher gain setting).
The auto setting plays around with these settings for you to get the best picture for you.
Sonar setup 
