master_baiter Posted September 6, 2005 Share Posted September 6, 2005 i just bought my first boat (used) on fri and it already has a fish finder a humming bird not sure of the model name but when i was in the boat launch maybe 3 feet max it was reading 25+ feet with alot of static lines on the screen. Some guy said i needed a different style of spark plugs. Any tips would help thanks in advance Quote Link to comment Share on other sites More sharing options...
Yankee_Bassman Posted September 7, 2005 Share Posted September 7, 2005 My Humminbird does the same thing in less than 3 feet of water...did it work ok in deeper water? If so, don't sweat it..... Quote Link to comment Share on other sites More sharing options...
Ben Posted September 7, 2005 Share Posted September 7, 2005 If you run in the AUTO mode, it's common for depth finders to read deep in shallow water, or to take a few minutes to adjust to the proper depth after moving to a new location. This is caused by the gain being too high and the unit reading harmonics (additional echoes) of it's orignal first pulse. Making the unit think it's in much deeper water than it really is. Thinking it's in deep water, it cranks the gain up even more, picking up even greater harmonics. The harmonics are multiples of the actual depth, so if the depth is 5 ft, a 10th harmonic would make the unit think it's 50 ft. The best way to solve this is to run the unit in the manual mode. Most of the time, I run my gain between 95 and 100%. I can see 1/4 oz jigging spoon and tube worms in 30 ft of water with no problem. I have seen fish as small as three fingerd bream when they hit the spoon or tube. With everything else properly adjusted, it shows very little trash but wealth of other info. Thermoclines show up almost as well as the bottom contour. When I go shallow I adjust the gain so the first bottom shows up and none of the other. However, it I'm going to be fishing that shallow less than five ft, I turn the unit off, it's not needed and the pings can spook fish. Quote Link to comment Share on other sites More sharing options...
master_baiter Posted September 8, 2005 Author Share Posted September 8, 2005 no it still does it n deeper water. i will try the gain thing next trip out thanks Quote Link to comment Share on other sites More sharing options...
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