Best practices for using Fish Finder and Radar

[lakershen]

My new offshore boat has the following Furuno package installed:
TZT3 MFD (2)
DFF3D
165T-TM54 (transom mount transducer for DFF3D)
B175HW
B175L
SCX20 (heading sensor)
DRS12ANXT/4 (solid state 4' open array radar).

I am fishing very hard in the Upper Keys, backcountry inshore fishing, 30' patch reef bottom fishing, 200' wahoo trolling, 100' to 200' wreck fishing, 200' to 800' Mahi and Tuna trolling, 600' to 1000' deep dropping for snowy grouper, tilefish, and queen snapper, and 1500'+ for swordfish.

I also have a bay boat with a Garmin package installed. The transducer is a GT51M through-hull transducer. All my fish finder-related experience is on the bay boat with Garmin electronics.

I have been trying pretty hard to dial in my new Furuno package. I watched every video on YouTube about Furuno, and I read through a lot of posts about fish finders, transducers, and radar online. Still, I have a lot of questions.

The biggest question is: what is the best practice for using the Furuno fish finder? Here are some related specific questions:

1) Should I keep both B175HW and B175L running at the same time? I heard there might be an interference problem. Right now, I keep them both on, with one displayed on each TZT3.

2) While trolling at a speed of more than 5 mph (about 700' deep), the B175L's reading is very noisy and unusable. The B175HW is a little bit better, but not as good as my GT51M. On the bay boat, at any speed slower than 25 mph, the fish finder has a pretty clear display, good enough to find a new wreck holding fish. Is this by design, or do I need to adjust the fish finder settings? Right now, I have been using auto fishing mode. My Furuno package was installed by a very reputable marine electronics shop, who is familiar with both the boat and Furuno. I think they should have installed everything properly.

3) What is the ideal depth for both transducers? I understand the basics: low-frequency transducers are good for deeper water and provide a wider view, while higher frequency is good for shallower water and has better accuracy. The B175HW is supposed to have a depth limit of 500', but based on my experience, it is working fine at a depth of 700'.

4) While drifting for deep dropping, should I use bottom lock, zoom, or shift? I am using bottom lock with a split screen now, but I watched a YouTube video where the YouTuber said shift is the better feature to use.

5) Another problem is the depth/bottom reading. My GT51M can read depth pretty well even at speeds of 30 mph+. The depth reading is pretty accurate and consistent. However, with the B175HW, the depth reading is all over the place at high speed—sometimes it is good, sometimes it reads thousands of feet, and sometimes there is no reading. Is there a way to fix it? I never tried to read depth on B175L while running high speed.

6) On the TZT3 fish finder, there is an HF and LF setting. Should I change it under different conditions? Right now, I am just using the default setting. I understand that the B175HW has a frequency range of 150 to 250 kHz. How does it work? Does the transducer generate ultrasonic waves at any frequency between 150 to 250 kHz?

How about the DFF3D? What is the best practice for using it? I have the CMOR mapping now, so the 3D bottom mapping feature of the DFF3D is less important to me. There are quite a few very cool viewpoints, but I just don't know how to use them. I use the traditional 2D fish finder almost 100% of the time. I know that DFF3D is a game changer, but as someone new, how can I learn to use it effectively?

Two of the biggest reasons for choosing Furuno are the DFF3D and the better solid state open array radar. I am very excited to use the radar to find birds. I have been offshore a few times trolling for Mahi and Tuna, including one trip with a Furuno tech on board. I have never been able to find any birds using the radar. All I have been seeing are either big/strong signals (boats) or small/weak signals/noises that are hard to tell whether or not they are birds. I ran to a signal twice, and after a two mile plus run, I found nothing. I understand the birds are not always there, and I need to spend more screen time to get everything dialed in. In the real world, what is the best practice to find birds using Furuno radar? All videos I found online about the bird mode are more like promotional videos—too short and nothing practical.

I still think I got the best electronic package for recreational fishing. I am willing to spend time learning. Hope you guys can help me shorten the learning curve. Thank you so much!

 

[Johnny Electron]

Reading the post, my thought is it doesn't matter what transducer, or what you spent, or who makes it; if you have water turbulence over the face of a transducer you are done for. There is no changing physics. The transducer placement on the B175s sound like an issue if sitting still or slower speeds works. @Deep Blue would be best to comment on the general acoustic settings for your fishing but it is a bit like open to what one likes to see. Everyone has different taste so there isn't normally magic settings that are given out that works for everyone but he should be able to point you the right direction.

 

[ToddF]

1) I would probably stick with one or the other (HW for shallower targets and L for real deep stuff) but if you use both setting interference rejection to High would probably work best. Should probably be doing that anyway if running DFF3D.

2) My B175HW works clear to almost 20knts. Above that I get cavitation. There's a Nav mode for the fishfinder that will lower gain and reduce other sensitivities to get a cleaner pic. You should be getting much better than 5knts. People here are going to need pics to help. Location of bottom of hull with transducer location and of your screen while running

3) Can only speak for the B175HW. Depends on water clarity but at least down to 600' but an stretch it out to 1000' by lowering frequency range and adjusting pulse length (longer) and increasing gain.

4) I shift. Primarily because its easy but also because my understanding is you have more pixels dedicated to the range you care about, rather than spread over the entire water column. Could be totally wrong but I'm going with this till corrected. There's a use for each mode though. The operators manual does a good job spelling it out. Basically it depends what you are looking for (bottom detail, fish holding close to botttom, etc)

5) I think your comparing to your old transducer, which essentially has a fairing block to a flush mount.... Its just not going to compare well at speed. But again you should do much better than 5knts.

6. HF is for your B175HW LF for the B175L. The chirp transducer will default operate through that entire range when set to Chirp (Screen will display 200kw though). You can also set it to run at any smaller range between 150 and 250kw or just a single number. I think it allows you 3 preset frequencies. Your only limited by your imagination as to what you'll use different frequencies for but generally lower frequencies penetrate deeper and make smaller fish look bigger, while higher frequencies provide greater detail on targets and bottom detail but are limited by depth.

7. DFF3d has a lot of topics here to search. Honestly its a bit too much to explain. Best practice is get the single beam dialed in an area you already know, then adjust the triple beam in same area. Start with the auto fishing mode and start adjust gain, speed, clutter, and other adjustments till the screen looks good (a little clutter but not too much) and then till your PBG trail matches what you know is down on the bottom. Its worth getting to learn but it takes hours and frequent adjustments for speed, temp, use, and water clarity.

8. Not much help here as I have the radome but even with that I can see birds. It does need to be set to bird mode though specfically and I believe sea state moderate is most useful. Practice with known birds and be realistic with your range. I'm not convinced my radar will beat my binoculars but haven't spent a bunch of time on it.

 

[Quitsa]

If you want to see birds with the radar, the NXT open array does very well with the same approach that has worked for many years with the magnetron radars. First, turn off the filters (sea state and rain) setting them to manual and zero. Select the range you feel most appropriate, recognizing that unless it is very calm or you are looking for big birds like pelicans, four miles is about as good as you can realistically expect. With the higher power DRS25A-NXT on my boat, 6 to 8 miles is feasible on calm days so you might do a little better. Now set the gain to manual and gradually increase gain until you see a lot of speckles on the display, then reduce the gain a little until most of the speckles go away. Finally, turn on the target trails set to 30 seconds.

At this point, you should see the birds if there are any. They will typically have small color smudges from the 30 second target trails because of course they are moving. Usually I slow down to trolling speed so the boat is not changing attitude a lot, which makes it easier to detect the birds.

You can use the bird mode setting on the radar, which sort of duplicates the above process automatically. However, my experience with bird mode on a DRS25A-NXT is that manual tuning produces better results once you get the hang of it and know what you are seeing.

Note that when you change the range in manual mode, you will need to adjust the gain again. It is also a good idea to clear the target trails regularly.

I prefer to use the white radar display background, which seems to make it a little easier to see small targets.

Another thing that is pretty important is to ensure that your radar pedestal was properly installed and shimmed so that the beam is not pointing too high or too low. That can make quite a difference in performance that is more noticeable with a challenging target like a bird than for seeing boats or the coastline.

 

[lakershen]

Reading the post, my thought is it doesn't matter what transducer, or what you spent, or who makes it; if you have water turbulence over the face of a transducer you are done for. There is no changing physics. The transducer placement on the B175s sound like an issue if sitting still or slower speeds works. @Deep Blue would be best to comment on the general acoustic settings for your fishing but it is a bit like open to what one likes to see. Everyone has different taste so there isn't normally magic settings that are given out that works for everyone but he should be able to point you the right direction.

Thanks. As I said, the Furuno package was installed by a well respected electronics shop not only familiar with Furuno, but with the boat. I hope they did not mess it up. I hope @Deep Blue can give me some guidance.

 

[lakershen]

1) I would probably stick with one or the other (HW for shallower targets and L for real deep stuff) but if you use both setting interference rejection to High would probably work best. Should probably be doing that anyway if running DFF3D.

2) My B175HW works clear to almost 20knts. Above that I get cavitation. There's a Nav mode for the fishfinder that will lower gain and reduce other sensitivities to get a cleaner pic. You should be getting much better than 5knts. People here are going to need pics to help. Location of bottom of hull with transducer location and of your screen while running

3) Can only speak for the B175HW. Depends on water clarity but at least down to 600' but an stretch it out to 1000' by lowering frequency range and adjusting pulse length (longer) and increasing gain.

4) I shift. Primarily because its easy but also because my understanding is you have more pixels dedicated to the range you care about, rather than spread over the entire water column. Could be totally wrong but I'm going with this till corrected. There's a use for each mode though. The operators manual does a good job spelling it out. Basically it depends what you are looking for (bottom detail, fish holding close to botttom, etc)

5) I think your comparing to your old transducer, which essentially has a fairing block to a flush mount.... Its just not going to compare well at speed. But again you should do much better than 5knts.

6. HF is for your B175HW LF for the B175L. The chirp transducer will default operate through that entire range when set to Chirp (Screen will display 200kw though). You can also set it to run at any smaller range between 150 and 250kw or just a single number. I think it allows you 3 preset frequencies. Your only limited by your imagination as to what you'll use different frequencies for but generally lower frequencies penetrate deeper and make smaller fish look bigger, while higher frequencies provide greater detail on targets and bottom detail but are limited by depth.

7. DFF3d has a lot of topics here to search. Honestly its a bit too much to explain. Best practice is get the single beam dialed in an area you already know, then adjust the triple beam in same area. Start with the auto fishing mode and start adjust gain, speed, clutter, and other adjustments till the screen looks good (a little clutter but not too much) and then till your PBG trail matches what you know is down on the bottom. Its worth getting to learn but it takes hours and frequent adjustments for speed, temp, use, and water clarity.

8. Not much help here as I have the radome but even with that I can see birds. It does need to be set to bird mode though specfically and I believe sea state moderate is most useful. Practice with known birds and be realistic with your range. I'm not convinced my radar will beat my binoculars but haven't spent a bunch of time on it.

Thank you @ToddF . It is exactly the feedback I am looking for. It will certainly shorten my learning cure. A lot of information to digest. Will take my time and study your feedback. Unfortunately, the brand new Seakeeper on my boat stopped working. The engineer sent by Seakeeper broke my bilge pump by accident. Not able to use the boat any time soon.

 

[lakershen]

If you want to see birds with the radar, the NXT open array does very well with the same approach that has worked for many years with the magnetron radars. First, turn off the filters (sea state and rain) setting them to manual and zero. Select the range you feel most appropriate, recognizing that unless it is very calm or you are looking for big birds like pelicans, four miles is about as good as you can realistically expect. With the higher power DRS25A-NXT on my boat, 6 to 8 miles is feasible on calm days so you might do a little better. Now set the gain to manual and gradually increase gain until you see a lot of speckles on the display, then reduce the gain a little until most of the speckles go away. Finally, turn on the target trails set to 30 seconds.

At this point, you should see the birds if there are any. They will typically have small color smudges from the 30 second target trails because of course they are moving. Usually I slow down to trolling speed so the boat is not changing attitude a lot, which makes it easier to detect the birds.

You can use the bird mode setting on the radar, which sort of duplicates the above process automatically. However, my experience with bird mode on a DRS25A-NXT is that manual tuning produces better results once you get the hang of it and know what you are seeing.

Note that when you change the range in manual mode, you will need to adjust the gain again. It is also a good idea to clear the target trails regularly.

I prefer to use the white radar display background, which seems to make it a little easier to see small targets.

Another thing that is pretty important is to ensure that your radar pedestal was properly installed and shimmed so that the beam is not pointing too high or too low. That can make quite a difference in performance that is more noticeable with a challenging target like a bird than for seeing boats or the coastline.

Thank you so much, @Quitsa . Very helpful information. I will follow the process you described once the boat is repaired. Two quick follow-up questions:

1) Once you see the birds, what do you do? Do you run the boat to the target (birds), or run the boat toward the target, stop at a certain distance, and use binoculars to confirm the target?
2) Is there a way to visually detect whether or not the radar pedestal was properly installed and shimmed? One thing I noticed is that in bird mode, there were a lot of noises around the boat. The Furuno tech told me that it is due to the way the radar was installed and the flares of my hardtop.

 

[Quitsa]

Thank you so much, @Quitsa . Very helpful information. I will follow the process you described once the boat is repaired. Two quick follow-up questions:

1) Once you see the birds, what do you do? Do you run the boat to the target (birds), or run the boat toward the target, stop at a certain distance, and use binoculars to confirm the target?
2) Is there a way to visually detect whether or not the radar pedestal was properly installed and shimmed? One thing I noticed is that in bird mode, there were a lot of noises around the boat. The Furuno tech told me that it is due to the way the radar was installed and the flares of my hardtop.

In our area, if there is a decent size flock of birds offshore it means there is bait in the water and probably tuna so I will just run to the spot and set up trolling. It isn't worth going too far of course because the fish may not be feeding any more.

I don't think there is an easy way to visually determine that the alignment of the radar is correct. The radar has a 22 degree vertical beamwidth so it has some tolerance. Ideally you should start with the radar mounted so the center of the beam is parallel to the surface of the water. Of course the problem is that depending upon your hull design and the speed you are traveling, the hardtop or other mounting surface will not remain at a constant angle relative to the surface. On my boat, the hardtop is close to horizontal at rest. At displacement speed, it is at an up angle of 2-3 degrees, which increases to 5-7 degrees or so at slow planing speed and then decreases to 3-5 degrees at fast planing speed. Since the most important consideration for me is safely navigating in fog, we chose to mount the radar so it points down about 4 degrees. That means it has the best overall performance at the slow planing speed I usually run in fog.

You can use the Measure app on an iPhone to check the running angle of your hardtop by the way. it's pretty accurate. I use the pitch data output from the SCX-20 to check the running angle. You can use that if you have one.

 

[Deep Blue]

​

lakershen,

Here are some tips that you might find useful: All Furuno fish finders include a feature that allows the unit to automatically set the Sensitivity (GAIN). The effectiveness of this feature varies widely based on water conditions, temperature, salinity, speed, and other manual settings, including the type and/or placement of the transducer.

To ensure the best results manually adjust the unit’s sensitivity. So I use these following steps will ensure the best fish finder performance:

• Bring your boat to the depth that you commonly will be operating the unit, (preferably more than 20 ft.). Do not attempt to do these settings while in shallow water. As the cone of the bottom coverage from even the best transducer used in shallow water is so small that unit will only be good for showing digital depth.
• Turn OFF the Auto-Sensitivity (GAIN) feature and then turn OFF the Auto-Range feature (you can turn on this feature back on later).
• Manually adjust the Range to more than twice the depth. If you are in 20 ft. of water, then you’ll need to adjust to 50 ft. (as 40 ft. will not work). You can even set the Range to three times the depth and get the same results.
• Adjust the Sensitivity (GAIN) so that you can just see a faint second bottom echo, if your depth is approximately 20 ft., then you will see this echo at 40 ft. The second echo occurs because the fish finder is hitting the bottom of the seabed, and then reflecting back up to the transducer again. The presence of the second echo ensures that the full signal is being picked-up by the transducer. If your Sensitivity (GAIN) is too high, then signal will be distorted, and you will have trouble distinguishing between the bait and fish.
• Re-adjust the Range to your desires depth and then turn ON your Auto-Range feature. Leave the Auto-sensitivity and any Fish ID…OFF. (for now...)

Periodically re-adjust the sensitivity of your fish finders unit especially when moving the boat to an area when one of more environmental factors have changed. The optimal Sensitivity (GAIN) depends on the following factors:

• Water Depth
• Water Temperature / Density
• Water Clarity
• Salinity (this is critical around the outflows of rivers mouths, near glaciers, fresh water lakes, etc.)

Boat speed can also change the optimal desired settings. Less GAIN may be required when a boat is drifting slowly in a calm water than when the boat is trolling or cruising. The signal loss can be so significant that at higher speeds full GAIN may be required to get any consistent bottom readings. For these situations the Auto-Gain features is probably the best bet (as you are probably not going to mark any fish anyway).


DFF3D General Information and Settings:
Beam angle and beam width only affects the triple beam view; best to start narrow at 20/20/20, or 30/30/30, widen to 40/40/40 when looking for hard vs. soft bottom (more evident in side beams); look for a tail echo in the side beams for hard vs. soft bottom

The DFF3D's transducer contains 8 little transceivers (elements) port to starboard (called beam forming); this is done by phasing the TX and RX

Cross Section and 3D History
When using this view the beams are fixed at 120 degrees port/starboard and 10 Degrees fore/aft History not available (swipe right) is a
result of the memory being full.

Try running the Gain higher in order to see more targets; as a starting point try Gain = 80 for Triple Beam and Gain = 70 for Cross Section; if you are seeing too much speckle you can just always reduce the Gain.

You can also adjust TVG curves and clutter but you need to go to the menu to adjust; or try setting TX Pulse to Short-1 for better near-bottom fish separation; this is especially true if your fishing depth is less than 400 feet

3D Sounder
Seabed Echo Calibration (higher is better); lower will take near bottom fish targets and blend with the bottom; higher will provide more target separation. Look at color scale at left of screen; red to white means shallower than present setting.

Tap the "A" to switch to Manual; then tap on the low number or high number and you can set to desired depth It's worthwhile to take a setting from one limit to the other and see what it does. The number of fish targets that can displayed, however the system will keep adding targets but drop off the older ones.

Cross Section
For better fish separation try adjusting the Echo Smoothing (Distance) to Low or Off

- Deep Blue

 

[lakershen]

​

lakershen,

Here are some tips that you might find useful: All Furuno fish finders include a feature that allows the unit to automatically set the Sensitivity (GAIN). The effectiveness of this feature varies widely based on water conditions, temperature, salinity, speed, and other manual settings, including the type and/or placement of the transducer.

To ensure the best results manually adjust the unit’s sensitivity. So I use these following steps will ensure the best fish finder performance:

• Bring your boat to the depth that you commonly will be operating the unit, (preferably more than 20 ft.). Do not attempt to do these settings while in shallow water. As the cone of the bottom coverage from even the best transducer used in shallow water is so small that unit will only be good for showing digital depth.
• Turn OFF the Auto-Sensitivity (GAIN) feature and then turn OFF the Auto-Range feature (you can turn on this feature back on later).
• Manually adjust the Range to more than twice the depth. If you are in 20 ft. of water, then you’ll need to adjust to 50 ft. (as 40 ft. will not work). You can even set the Range to three times the depth and get the same results.
• Adjust the Sensitivity (GAIN) so that you can just see a faint second bottom echo, if your depth is approximately 20 ft., then you will see this echo at 40 ft. The second echo occurs because the fish finder is hitting the bottom of the seabed, and then reflecting back up to the transducer again. The presence of the second echo ensures that the full signal is being picked-up by the transducer. If your Sensitivity (GAIN) is too high, then signal will be distorted, and you will have trouble distinguishing between the bait and fish.
• Re-adjust the Range to your desires depth and then turn ON your Auto-Range feature. Leave the Auto-sensitivity and any Fish ID…OFF. (for now...)

Periodically re-adjust the sensitivity of your fish finders unit especially when moving the boat to an area when one of more environmental factors have changed. The optimal Sensitivity (GAIN) depends on the following factors:

• Water Depth
• Water Temperature / Density
• Water Clarity
• Salinity (this is critical around the outflows of rivers mouths, glaciers, etc.)

Boat speed can also change the optimal desired settings. Less GAIN may be required when a boat is drifting slowly in a calm water than when the boat is trolling or cruising. The signal loss can be so significant that at higher speeds full GAIN may be required to get any consistent bottom readings. For these situations the Auto-Gain features is probably the best bet (as you are probably not going to mark any fish anyway).


DFF3D General Information and Settings:
Beam angle and beam width only affects the triple beam view; best to start narrow at 20/20/20, or 30/30/30, widen to 40/40/40 when looking for hard vs. soft bottom (more evident in side beams); look for a tail echo in the side beams for hard vs. soft bottom

The DFF3D's transducer contains 8 little transceivers (elements) port to starboard (called beam forming); this is done by phasing the TX and RX

Cross Section and 3D History
When using this view the beams are fixed at 120 degrees port/starboard and 10 Degrees fore/aft History not available (swipe right) is a
result of the memory being full.

Try running the Gain higher in order to see more targets; as a starting point try Gain = 80 for Triple Beam and Gain = 70 for Cross Section; if you are seeing too much speckle you can just always reduce the Gain.

You can also adjust TVG curves and clutter but you need to go to the menu to adjust; or try setting TX Pulse to Short-1 for better near-bottom fish separation; this is especially true if your fishing depth is less than 400 feet

3D Sounder
Seabed Echo Calibration (higher is better); lower will take near bottom fish targets and blend with the bottom; higher will provide more target separation. Look at color scale at left of screen; red to white means shallower than present setting.

Tap the "A" to switch to Manual; then tap on the low number or high number and you can set to desired depth It's worthwhile to take a setting from one limit to the other and see what it does. The number of fish targets that can displayed, however the system will keep adding targets but drop off the older ones.

Cross Section
For better fish separation try adjusting the Echo Smoothing (Distance) to Low or Off

- Deep Blue

Thank you so much. Will follow your instructions and spend more time on the boat.