Any of you guys that use fish finders. My lowrance lms 520c 200hz works great in fresh water but I was very disappointed when I went to Catalina island (salt water) It would not penetrate the temp layer at all and now fish identified. Is this normal (that's what bass pro shops tells me) or do i need to practice some more?

i was looking into fish finders recently and read that for salt water, a dual beam unit is recommended.

Did you check the gain?

Was the transducer kicked up due to hitting something (like the trailer when launching)?

What is the frequency? A dual 50/200 Hz is required for use in deep and shallow water.

DeepV, no there was nothing wrong except the picture was just filled with all yellow. After some more study it seems I may have had the gain too high. It's a 200hz model. I have already checked back on mohave and it worked fine.????

I boat in salt water and use a Lowrance Dual Frequency unit. I have not been out over about 150 feet depth since installing this unit --(Key West area) -- but no issues at that depth in salt water -- should go much much deeper ---

You need 50 Hz to go over about 200feet.