Fishfinder output power

SS MAYFLOAT

Admiral
Joined
May 17, 2001
Messages
6,372
I've been looking for a FF for awhile now. I usually always go by the spec sheets and customer comments.<br /><br />I have found an area that I'm having problems getting an answer for.<br /><br />I fish in fresh water lakes and rivers. Very rarely I will be in water 100' or more. Average depth would be 15 to 35'.<br /><br />Will having too much output power (500 watts rms) effect the fishing in the range that I fish in? Will the action of the transducer send the fish away from the boat? Thanks
 

ThomWV

Senior Chief Petty Officer
Joined
Dec 19, 2003
Messages
701
Re: Fishfinder output power

No, it won't scare the fish away. You don't need anywhere near 500 Watts RMS in that sort of water. In fact you could get away with 50 watts quite nicely. More is better of course.<br /><br />You should know that the Gain on the fish finder doesn't decrease the power output, it decreases the receive sensitivity. I think a lot of folks aren't clear on that.<br /><br />As to the power, in a sense its sort of meaningless in water that shallow. We've all heard the argument that says its just like a flash light and that the brighter it is the better you can see. Well, that's true but in this case we're talking about looking though an empty room and trying to espy a cow. Once you've got enough light to recognize it as a cow you really don't need any more, let alone a floodlight.<br /><br />However I can tell you, I have a 600 watt fish finder (Furuno 582L) connected to a high performance 1-kW transducer (Airmar M260), and when we are in 35' of water absolutly no fish could pass under our boat without being detected. It simply could not happen. This would remain true in depths up to about 150 feet.<br /><br />Thom
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: Fishfinder output power

In fresh water down to 100 feet I think 1500 PeP is enough (187.5 Watts RMS). You also will want it to be a 200khz unit for more detail. Many older high power unit had trouble is shallow water (less than 15 feet). Newer unit seen to work better. <br /><br />Some fish like Salmon hard to see on a fish finder. I think I see Salmon when I turn the sensitivy up high enough the the screen is 1/4 black. Some say the only way you see Salmon is to see the cavity when the salmon has eaten a bunch of bait fish. In this case more power may help.<br /><br />Do fish feel the pluse, that is a good question. I can fell the pluse with my foot or hand under the transducer. Many fish can fell the movement of other fish with their latteral line on their side. I can not feel the movement of other fish with my hand or foot, so are fish more sensitive, I think so. Still most people do not fish within the cone angel of their transducer. In 30 feet of water the 20 degree cone angle would cover a 10 foot circle under the transducer. Most fishing is done out more than 5 feet from the boat.
 

SS MAYFLOAT

Admiral
Joined
May 17, 2001
Messages
6,372
Re: Fishfinder output power

Cool, thanks guys for your input. I have found an Eagle Seafinder 320DF. It has 500 watts rms and good down to 1500'. Dual freq 200/50hz. This unit new is less than $225. For the power output, this is the cheapest unit I have found. <br /><br />I have had a few Eagles in the past with good results.<br /><br />I still haven't found a FF that will tell if the fish are hungry or not. :D <br /><br />Thanks again for the input!
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: Fishfinder output power

Easy to tell if they are hungry out here in the West. Just get a surf board and paddle out. Do a lot of splashing if you come back with all limbs they were not hungry.
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: Fishfinder output power

The Eagle 320DF is a great unit for shallow water, less than 150 feet. You may not need the dual frequency unless you troll with downrigers. The wider cone angle of the 50khz will usually see your downrigger ball where the 200 Khz transducer will not.
 
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