FF depth display, numbers versus picture

[Ranger]

We have two depth sources, one of which is the TZT3 with M525-STID (B744V) transducer, both sources adjusted to show actual water depth (via keel draft setting, etc.).

In these pics, stationary in our slip, actual depth is ~6.0 ft. A-Scope and Bottom Discrimination are ON. The depth line in the "picture" is right at 6', as expected. OTOH, the numeric presentation is jumping around at about 1.5-1.7' and that number is repeated in the Data Box.





What is now that lower white box was an actual bottom discrimination display - sometimes -- the other day when we were trolling (~3 kts)... but it eventually turned white...

When we winterized last season, that numeric value in the Data Area matched our other depth source.. Turning the systems on this year (don't remember making any changes anywhere) we get this seeming mismatch.

I've been all over the manual and all over the menus and can't find (or recognize?) a setting that's causing all this.

Can someone point me to the menu value(s) to check?

-Chris

 

[TheReaper]

Check your depth source in home-settings-initial setup-data sources. If not that, check home-settings-fish finder, ensure fish finder source is correct. The bottom discrimination information will only work in 5-100 meter depths.

 

[Johnny Electron]

Do not run both accufish and BD at the same time either as that will cause issues. It is one advanced feature or the other, not both.

 

[Ranger]

Check your depth source in home-settings-initial setup-data sources. If not that, check home-settings-fish finder, ensure fish finder source is correct. The bottom discrimination information will only work in 5-100 meter depths.

Thanks, I'll check those!

I eventually twigged on to the white box probably replaced the bottom composition display once we got into shallower water. Which in turn becomes a bit of a disappointment, since we can almost always be anchoring in 10-12' of water for an overnight. Not to worry... I can go with the flow...

Do not run both accufish and BD at the same time either as that will cause issues. It is one advanced feature or the other, not both.

Ah! Didn't see that. OK. Sure enough, we had both on at the same time. Thanks!

I notice in my pics, I had at some point messed with the frequency selection, ended up (at that time) on LF vs. the normal HF we can usually use more in relatively shallow waters around here. I've since changed that back to HF.

I have to add here how much I get a kick out of the Accu-Fish symbols. My guess is the programmer was really enjoying himself... when he made the larger size "fish" display a "smile"... Cracks me up!

-Chris

 

[Ranger]

Well...

I checked the two data source fields, both properly set to TZT16F.

I turned off A-Scope, Bottom Discrimination, Accu-Fish, Fish Alert... Bottom Search and Temp Graph already off... and here's what I got:



When it shows a number -- as in this pic -- the number is still incorrect (depth as this was taken was about 7.6').

Tried rebooting. Not much change. The TZT very occasionally flashes a credible depth number -- once that was even actually 7.6' same as other system -- but then it reverted to the 3.1/3.2' range... with a whole lotta white screen and the bottom echo only showing way up at the top of the screen.

??

Turned on Accu-Fish. Eventually the system settled down to where the TZT depth is tracking at 5' lower than the other system. For example, actual is 7.7', TZT shows 2.7". I think that might be significant, but can't find a 5' offset of any sort anywhere in the settings... Still a page of white, with bottom echo only near the top pf the screen...

??

-Chris

 

[Ranger]

And now this, after turning Auto Range back on. (Don't remember turning it off...)



No clue what to do about the upper maroon area. The bottom echo is still right on with the other system, a little over 7' just now. The number display is only sometimes approx 5' wrong., more often some random number approx 4.3' wrong.

-Chris

 

[TheReaper]

So, fish finders are designed to be used in 15ft of water or deeper. Anything less is a bonus. If you look at your picture, the range scale is 0-120ft...the bottom is jammed up at the top. Try adjusting the range to double whatever the depth you think you're in. For 3.2ft or 7.6ft, adjust to 0-10 or 0-15 scale. If you see the bottom at 7.6ft (or whatever depth you're in when you check this), then the number displayed in the bottom left should reflect that. If not, the depth offset is incorrect. To fix the depth offset:

1. Go to Home-Menu-Initial Setup
2. Set Depth Display to “Under Keel”
3. If you want to add (+) the depth number in the data box, put that number in “External Transducer Draft”
4. If you want to subtract (-) the depth number in the data box, put that number in “Keel Draft”

 

[Ranger]

I see the word "range" in a bunch of places, but not sure where to set the "range scale" ?

If you see the second picture in my last, with the two maroon bands... the depth scale is about 8'. Can only barely see the range numbers on the right side of the upper maroon band. (And never saw an upper maroon band like that before.)

Current settings -- and these are what worked last year to get this system to display the same depth as the other system -- are:
Initial setup
Depth Under Keel
Ext transducer = 0.0
Keel draft (actually our nominal prop draft) = 4.6'

Fishfinder Initial Setup
Transducer draft 3.6'

All that worked from last September... throughout the end of last season... and it all seems different now that we've started up again this year. And we usually only use the system for depth read-out; don't actually use the FF as an FF very often, usually only a few times in May...

See here for all the pain last year...

R

Thread 'Depth issues (read-out not responding to setting changes)'

Aug 23, 2024

Or maybe the math is just kicking my...

TZT16, with 525STID-MSD. Keel daft (actually prop draft) is 4.6". The transducer is 3.6' below the waterline.

Actual depth in our slip just this minute is 5.3' -- according to the other depth finder, which I've checked against an actual bottom measurement using a boat hook.

FF read-out is hovering around -2.4'... minus 2.4'... seemingly no matter what I do, no matter where I set the "transducer draft" number. Currently set to 0.0. Have tried 1.1' (near enough to transducer draft, over prop depth), 3.6' (depth below waterline), several other...

• Ranger
• Replies: 7
• Forum: NavNet TZtouch3

As of just a minute ago, depth is actually about 6.6' and the Furuno unit shows ~1.8.... when it shows a number at all. The bottom echo line is about 6.6' though.

-Chris

 

[Ranger]

OK, think I found the range thing. Manual, section 7.4. I'd had it set to Auto range selection. (Forever; since installation.) Also activated the slider bar, once I found how to do that.

Changed to what you see here:



Actual depth is ~6.6'.

-Chris

 

[TheReaper]

I was commenting on your first picture before you sent the second one. The "Range Scale" I was referring to is circled in red. The scale is adjustable if you are not in range isn't set to "auto range". Then you use your finger to drag the scale to show the correct number at the bottom. In your second picture, using auto range appears to be working well, so you don't need to adjust the range.


Get rid of the transducer draft of 3.6ft...change it to 0.0. That is where the big red band at the top is from. Use my formula to get the correct number for depth that you want to see.

1. Go to Home-Menu-Initial Setup
2. Set Depth Display to “Under Keel”
3. If you want to add (+) the depth number in the data box, put that number in “External Transducer Draft”
4. If you want to subtract (-) the depth number in the data box, put that number in “Keel Draft”

As for your comment about not using the fish finder for fishing, but rather for navigational depth...that is not what they are designed for. If you want reliable navigational depth, you should be using a NMEA2000 smart sensor and a data box with depth number in it.

 

[Ranger]

As for your comment about not using the fish finder for fishing, but rather for navigational depth...that is not what they are designed for. If you want reliable navigational depth, you should be using a NMEA2000 smart sensor and a data box with depth number in it.

Yep, got that. This is the redundant system that gets me bottom discrimination (used more often than FF) and FF for a few trolling runs in May-ish. Otherwise, it's the number in the data box that I'm using to augment our other system... which is a DST 810 on the NEA2000 network and displayed o the other MFD.

The boat's actual prop draft is 4.6'. The transducer is mounted at ~3.6' above keel (prop) depth). Current water depth is 6.7'. Doing it this way at least gets me a positive number in the data box...





So what's this telling me? Depth below the transducer? That can't be right; we'd be sitting on the bottom...

Before, I thought I had offsets entered so the data box depth number was water under the prop depth. And what I want is either water under prop depth (preferred) or sea level (I could live with it).

??

(I don't usually feel so obtuse...)

-Chris

 

[TheReaper]

That method I described will allow you to basically change the depth number to whatever number you want (like the old days when there was only a depth offset number to enter). If you take the numbers out of both spots...see what depth it shows. At that point, enter a number into either the external transducer draft setting to "add" to the displayed number or in keel draft setting to "subtract" from that number. Don't over-think it.

 

[Ranger]

Well, I wrestled it to somewhere I can live with (I think, at least for now), no clue why. (I hate that.)

I set the Depth Display to Under Keel. I set the Keel Depth to .8'. This after working sorta backward to discover a number (.8') that would make 7.2' true depth (other system) mate up with current depth-under-keel (props, 2.6') on the TZT.

The result is that we have true depth on the other system (e.g., 7.2') and depth under keel (props to dirt) about 2.8' on the TZT. No clue why that works. No clue how that factors with our 4.6' prop depth (below waterline) or with 3.6' transducer mount (above props depth).

Changing the External Transducer Depth setting to pretty much anything made pretty much no difference anywhere. 3', 15' whatever... made no difference.

BTW, the "true depth" came from pole-in-water measurements, then with keel offset entries on the other system to agree with pole depth.

In any case, thanks very much for your help. Trying to get ready for a trolling day tomorrow with guests aboard... and it's always a hoot when we show them the fish symbols... always crossing from our starboard side toward our port side...

-Chris

 

[Ranger]

Thanks again for your help; I was able to get it all squared away -- enough -- so yesterday's trolling worked fine. I got the math squared away enough so the number displayed is a reasonable version of our keel (max prop) depth. And I used the Auto Range and Accu-Fish...







We didn't actually catch squat -- but everyone had a good time, and those who viewed the screen enjoyed seeing the "fish" we should have been scooping up from time to time. As it happens, from comparison with other area fishing reports and where we were relative to all that... we're able to be pretty sure those were really fish with herds of bait (menhaden) that we were seeing on the screen... not just figments of the TZT imagination. And all those menhaden were probably why our striped bass targets didn't have much love for whatever lures The Mate tried throughout the session.



-Chris