fish specific frequency

First let me say that this forum is fantastic. I've learned more about sounders here in 2 hours than anywhere else!

I have a FCV 295 connected to an R209. I've heard that different frequencies work better for locating different species. Is there any rules of thumb I can follow to try and better locate fish? We do a lot of snapper fishing from 50' to 150', where in the frequency range should I be focusing my efforts.

I think I've figured out how to use the dual frequency to see two different frequencies at the same time, but how much a difference between the two frequencies should I be using?

Thanks,
Eric

EricSC,
Thank you for your question. Since we don't have too many Snapper in our area it's tough to said what frequency is best. I did do a frequency test with the R-209 to see what difference it made. This test was in a fresh water lake and the fish targets are probably Perch. To me the best frequencies in this test were around 50 & 190Khz. The nice feature about the FCV-295 is that you can program it to TX on two low frequencies or two high frequencies, instead of one of each. This way you can compare two low (or high) frequencies side by side to see if there is a difference. Please note that the FCV-295 is blocked from transmitting 53-65, 111-139 and 171-183Khz due to slight inverter noise.

Snips

Thanks Snips, I'll try 10KHz increments and see which looks the best then narrow it down from there.

Is there any rule of thumb connecting target size and frequency? In other words if you are looking for small bait use a higher or lower freq?

Eric

EricSC,
In "theory" higher frequency should display smaller targets better. Most of the time I run both frequencies to compare the returns.

Snips

A quick follow up. I found that turning down the clutter (from 40% to 20%) in combination with setting the power to max (from auto) has had the biggest effect. The bottom detail seems to have increased dramatically and target discrimination is also much better.

Eric

Eirc,
Thanks for the update. Here are a couple other setting changes you might try, set the TX Rate at 20 and under the TX/RX Menu change both the LF/HF TX Pulse to Short 1. When you change the Pulse Length the sounder is not outputting as much power so you will need to increase your gain a little bit. Two things happen with a shorter PL, the sounder starts transmitting faster and you should see better fish separation. These setting changes probably won't help much in really deep water but in waters less than 125fm they should help.

Snips

After reading through a bunch of posts here I had already made those changes but I had not gone out to see the effects. Now that you mention it I did have to run a higher gain this weekend and the bottom detail was significantly sharper. In addition briefly ran 190KHz and 200KHz side by side but I can't say I saw much of a difference. I'll have to give that another shot when I have more time.

I can definitely say that this tweaking has made a world of difference. I'm getting closer to Snips quality screenshots!

Eric,
Progress, I like it. Don't expect to see much (or any) difference between 190 and 200Khz. The frequency difference will need to be greater, say 140 to 200Khz. Keep on tweaking.

Snips