DFF3D for locating tuna?

[big_tuna_]

hello, I'm curious if anyone uses the dff3d sidescan to locate tuna? On the west coast we get bft tuna up to 300lbs and often there are no surface signals to let us know they are there...we often fish in the dark for them as well...so we depend on our electronics to locate them. I use b175hw and it works well but I have to practically run right over them. The larger sportfishing boats have a "radar" type furuno sonars which can locate schools of tuna couple hundred yards away in 360 degrees. Very impressive sonars but they are 30k and not practical for the recreational boater in his 23 boat.

I thought perhaps the DFF3d to locate tuna off to the side could be the next best thing other than spending 30k for 360 degrees. However, my boat is set up with simrad so if I was going to jump to the DFF3d I would need to spend probably 6k for mfd, control box, and transducer. I'm just wondering if that 6k is worth it or not....

Thanks in advance

 

[FishTech]

Just be aware that the DFF3D has a 120° beam width so it will not be looking too far sideways until you get some depth. If you wanted to do this I would add a true side-scan to the mix as well. Then you would truly have full coverage. Hopefully someone can offer some visual evidence. I know of a few people that do exactly what you are planning.

 

[Deep Blue]

big_tuna_,

95% of Albacore and Tuna guys are fishing in less than 350 ft. The DFF3D's Cross-Section was designed to display water column echoes (providing the operator with real time raw data on what the transducer seeing.) by using a 120° port & starboard beam width. However, keep in mind that the Cross-Section fore & aft beam width is only at 8°.

You can still use the Cross-Section for detection of baitfish and the distribution of any fish school concentrations within the water column, but as the fore & aft beam width being very narrow, and with the Albacore and Tuna typically moving very fast, these fish don't stay in the Cross-Section's beam width for very long.

Here is a picture of tuna that was detected using the DFF3D's Cross-section (bottom right in the picture) when they were hitting baitfish. I would use DFF3D's Cross-Section along with Side Scan and/or Triple Beam Sounder for complete coverage:

 

[Quitsa]

I use my DFF-3D while trolling for tuna, which is usually in 200-400 feet of water. It is quite useful, mostly in showing bait balls below the surface off to one side of the boat that would not appear on my regular narrow beam sounder. The 3D history map also shows marks well to one side. It certainly can’t duplicate what I have seen on other boats with the omni sonar that shows a complete circle around the boat. That being said, if I didn’t already have Furuno MFDs, I am not sure I would say it is so valuable as to justify spending so much to add it unless maybe you also do a lot of bottom fishing and would use it to locate and map structure. That’s where it really excels.

A cheaper option might be the new Airmar B175 medium ultra wide beam, which should show quite a lot. https://www.airmar.com/Product/B175MW

I have not heard any reports yet on those. I assume your current sounder could drive it.

 

[sdonx]

I use both the DFF3D and the sidescan to get a more complete 180* picture. But like DeepBlue says its just a thin slice of whats happening around you.

 

[ToddF]

Yes it works for tuna. I'm in your area and can say for sure we caught bluefin last year that we would have missed without DFF3D. Fish that didn't show at first on my B175HW, but did on the sides of the DFF3D triple beam. The main advantage is not just locating schools way off to the side, but knowing exactly which side they are off and how far off they are.

Since our bluefin (especially big ones) spend a lot of time at 120-400', it can effectively target them quite a ways off to the sides. It's definitely not sonar, and you can't chase a school down, or see one way out in front like a sportboat. But if you do run by school, it gives you a shot to know it, then to turn and find it. Triple beam gets you a wide sweep and its my favorite for searching offshore. Also, prefer the full 40 deg angle on the 3 beams (120) but narrow the width of each beam to 20deg. This leaves a little space between each beam, decreases crossover from one beam to the next, and find it pinpoints side targets more accurately.

You'll also probably need an SCX20 sat compass to get the full benefit of DFF3D so add that into your cost/value analysis. Lastly, it takes some time to learn how to setup and use. There's tons of settings (a positive thing) and sensitivities so it needs constant adjustment for changing depths, water temp, and clarity.