Losing Bottom with New TZT3 and B175M Transducer

seaveepete

Furuno Super Fan
I recently installed a new Furuno system including a TZTouch3 16" MFD and a new B175M low profile thru-hull transducer. When the boat is running inshore at more than about 20kts in calm water we lose bottom. Offshore in relatively calm conditions we're losing bottom at trolling speeds around 7 kts in 100'. We set the transducer to auto-fishing and also tried auto-cruising mode but still lost bottom.
The B175M is a zero degree unit installed on the aft part of the flat pad near the transom on a 29' SeaVee. The thru-hull installation looks textbook and there are no obstructions, water intakes, strakes, etc. ahead of this transducer.
I've installed a number of these low profile thru-hull transducers but this is the first TZTouch3 MFD I've installed.
Any thoughts on why this setup won't hold bottom in virtually perfect conditions?
 
Transducer install and location can be tricky sometimes. Almost always loss of bottom is install related not machine settings.

Got any pictures of your transducer as installed and showing the other penetrations, strikes, mounting location etc??

Phil
 
If you don’t suspect it’s a transducer install issue make sure that the tzt3 unit is grounded properly. You can also run a test by hooking up the tzt3 to a spare 12v battery making sure that nothing else is hooked up to that battery. If everything works well you’re looking at engine interference or another type of electrical interference jamming up the units performance. I have a b175m currently running off of a garmin unit but i’m looking to get a tzt3 soon and I had a similar issue when operating garmins chirp unit. If you’re just transitioning from traditional to chirp you’ll find out that the chirp systems are very sensitive but perform well if everything is installed properly.
 
What happens if you use manual gain settings? Have you tried that, steadily increasing the gain to see if the unit holds bottom?

It would take a lot of issues with the installation to mess up the display at trolling speed, which suggests there is something else happening. Although it is not very common, there the possibility that your transducer is faulty. This can be checked by an installer who has the Airmar test kit.
 
Maybe a dumb question, but maybe worth double checking - is the correct transducer selected in the transducer setup pages?
 
Thanks for the replies folks. I'll take a picture of the installation and post it here. I'll also double-check that the transducer is properly identified by the TZT3. Newer transducers like this one all have XID so they are automatically identified by the MFD but I will check. I did consider the possibility of interference but the cable is routed by itself until it enters the console so that is unlikely but I'll pursue that angle also.
Thanks again.
 
Can you also take picture of the fish finder display that also shows the SOG on the dispay (Navbar)?

It would be helpful to have a couple of photos of the fish finder display and speed of the vessel?

SOG "0"
SOG "5"
SOG "10"
SOG "15"
SOG "20"

What happens to the bottom if you make a long turn to port? Does it improve the bottom profile, less gaps?

How about a long turn to Starboard? Does it improve or get worse?

You may also try different trims? Sometimes you will see a change, for better or worse.

This will all be good info to have.
 
Here are a few pictures of the transducer installation under the boat.
First image is taken from forward looking aft and second image is aft looking forward.
xducer1_lookingAft.jpg
xducer2LookingFwd.jpg

I did check on a few items including grounding on the Furuno (good), reseated the pigtail adapter plug for the transducer, confirmed there are no kinks or nicks in the transducer cable and it is not running next to any wiring that would cause interference, and confirmed that the TZTouch3 is recognizing the transducer as the 1kW B175M.
The boat will be in the water again this weekend so we'll try to get some pics of the sounder at various speeds and trim angles, etc.
If there is no improvement the only idea I have left is to apply another 1/4" wide layer of 4200 and try to make a smoother transition between the hull and the front edge of the transducer by feathering that edge.
 
Did you ever figure out what was causing your issue? I'm in the process of doing a similar installation....
 
I have tzt2 and had to set bottom level to -20 to stop that. Not sure if that applies to your application or not.
 
Still losing bottom on the B175M transducer when running at any speeds about 25kts. Smooth water or choppy - doesn't matter. I also applied a little more 4200 on the leading edge to create a smoother transition between the transducer and hull.
Any other ideas?
 
Do you have the transducer hooked directly to the back of the unit? Post some pictures of what it marks like when its actually reading bottom and also of your transducer in the bilge.
 
There is a short Airmar adapter cable connected to the xducer which is connected directly to the TZTouch3. There is no breakout box or anything else involved. I've also made sure the xducer cable is not adjacent to any other cables that could be causing interference, etc.
 
C-bass suggested some photos at diffrent speeds. He can normally tell a lot from the fish finder screens at depth. I would recommend starting there if you wish to work the issue.
 
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