[Cutthroat]

You're right, Ken. The salt is to keep it from freezing.

I just used my new fishfinder to shoot through 12" of ice at Parvin Lake to read depths before drilling holes and to look for structure (or lack thereof). The 200K lowrance transducers can definitely handle this without a problem. It should work better with a salty brine to help transmit the sonar.

 

[Cutthroat]

good idea about the salty water to keep it from freezing, it wont help the transmision any if any thing it would hurt it but with just a small amout cant see that it would make a diff. salt water is more dense and all fish finders have a greatly reduced depth capacity in salt water

i wonder if a little alcohol/water would work to prevent freezing and would that be less harmfull to the enviroment than adding salt any thoughts?

Man, I don't think you could carry enough salt to be harmful. Besides, we mostly have reservoirs with some flow-through, here. salt doesn't stay put. Most aquatic organisms can handle a little salt in their water, too. Trout have no problem with it at all.