Bad Transom Transducer Readings, Any Tips?

[Casslaw]

Hello all, when I got this boat 3.5 years ago I put a Garmin 73cv at the console. I USED THE EXISTING HOLES IN THE TRANSOM to mount the ducer. I never had really good images but it was reasonable.

I recently got a 93sv so I put the 73cv on the trolling motor and simply swapped the 93sv and new ducer where my old stuff was.

With the 73cv up front...OMG how the image has changed! It looks like a Garmin ad! I can pick out specific crappie when I go over a school, see the bait they’re feeding on, etc.

The SI on the 93sv is just blah and the DI isn’t much better which instantly told me “hey dummy, your ducer is in the wrong spot!”

I’ve never dealt with aluminum boats (no pad) so I thought I was going to be ok using the location the factory put the original ducer.

Am I too far from center? Too high, too low? Any tips would be appreciated! Right now the top of the ducer is about 3/8” below the bottom of the strake. Here’s a couple pics. Thanks everyone.

[5965derek]

I don't see anything wrong with the location. My humminbird ducer on my triton aluminum rig is in basically the same place. You want the hull to basically split the transducer. It should be in clean water where it's at. Maybe a settings issue? Yours looks like it may be low but hard to tell from the angle in the pics.

[Casslaw]

When I bought this boat the little in dash Lowrance 5” was still hooked up so I used the same 2 holes for this bracket. Who wants more holes in their transom?

I would normally agree that it’s a settings issue except for the fact that when I moved my 73cv up front with the ducer mounted on the trolling motor it was such a shocking difference! I was always able to see different types of grasses pretty well but fish never did really look different than weeds. However now the 73cv is giving me images I could only have dreamt of before and the 93sv just looks blah!

I went under a bridge that has 6 piling, only 1 showed up on the side imaging...that’s an issue! I did lower the ducer about 3/8-1/2” to see what difference that makes but frankly I know that ducer is in plenty of water to return a good image. I will be able to see what affect it had this weekend and I will see what affect changing the angle of the ducer has as well.

[billwvu05]

I agree to split the transducer in half with the hull. Not sure if I interpreted you right but you should definitely not be right over a strake, should be off to the side. Tough to tell from photo but it appears to need tilted up slightly as well so it skims better. I would suggest a mounting plate where you can make adjustments without putting any additional holes in your boat to get it fine tuned. I went through probably 5-6 locations on my tin Ranger to get it right. I am far from an expert but this info from Sternmate helped me out.
http://www.sternmate.com/where.html

[Crappie Bob]

Mine is in the same place and what I found was if I trimmed up the outboard it didn't interfere with the side scan anymore.

[DanR]

Mine is in a similar location as well but probably dropped a little lower because I have a riveted bottom, I honestly don't see an issue with that location. Can you snap some screenshots to see the difference between the two? Really strange that you are seeing a big difference on DI. On SI, does one side appear better than the other?

[Casslaw]

I will take some screenshots tomorrow. I took a straightedge and the entire transducer and the bracket are under the hull, hence the roostertail it throws. I moved it as high as I could, but with the existing holes I can’t get it where 1/2 the ducer is under the hull. I’m getting a small mounting board so I don’t have to put more holes in the boat.

I always set the angle based based on the waterline on the side of the boat, which left the back of the ducer higher than the mount. I just leveled it with the bottom of the boat so I can see what that does.

Im going to spend some time tomorrow just working on the settings and scanning a bunch to see how different adjustments affect the image.

My boat has a stepped hull but the ducer is directly in the center of the step and there’s nothing on the hull that I can see that would effect the image other than the fact it’s a welded hull and not as smooth as fiberglass.

Thanks everyone for the advice.

[Casslaw]

After much looking on YouTube I set all my settings to the “best” according to the internet. On the water....disaster so I reset the unit to factory settings and started over. The pics below are pretty self explanatory, they look horrible! I included one from my front unit so you could see the difference. The front unit never gave images this good when it was at the console so that leads me back to transducer placement.

Im making a ducer board out of some ptfe board I have. Right now the entire bracket is under the hull about twice the thickness of my thumb so it’s just plain too deep. If you guys see anything that jumps out at you please let me know. Thanks, Chris

[tlefire]

When you get back to the water, see what it looks like when you are sitting still. I'm wondering if your getting some type of turbulence while your moving since it's as low as you say it is. My transducer is about 1/4 of an inch below the bottom.

[Casslaw]

That’s exactly what I’m thinking, and since moving my other one to the front made such a huge difference it makes sense. In the first picture you can see where I slowed to a stop and the top of the graph shows what I think is the fact that it’s mounted too low. It does disappear near the right of the screen but the rest of the screen still looks like poop!

[5965derek]

That top down imaging pic is definitely turbulence. You will see an improvement when you get it moved. I had a 73sv and 93sv and the 73 always had a little better picture quality. The side and down imaging on these units aren't the best but serviceable. I'd say once you get it moved you'll see a difference for sure. Also, the 73cv will always have a much better image in down imaging. You can research the 93sv and depending on which model/transducer you have yours may not have a down imaging element. It essentially uses side imaging to create the down image. Just something to be aware of so you aren't expecting more than its capable of

[Casslaw]

That top down imaging pic is definitely turbulence. You will see an improvement when you get it moved. I had a 73sv and 93sv and the 73 always had a little better picture quality. The side and down imaging on these units aren't the best but serviceable. I'd say once you get it moved you'll see a difference for sure. Also, the 73cv will always have a much better image in down imaging. You can research the 93sv and depending on which model/transducer you have yours may not have a down imaging element. It essentially uses side imaging to create the down image. Just something to be aware of so you aren't expecting more than its capable of

Thanks Derek, I got the 93SV for a very good price from a friend who only used it as his livescope unit so he never used the side imaging. It has the GT52 transducer if I have identified it correctly. I’ll obviously start getting the ducer in the correct location then go from there.

[Joe from Virginia]

You may need to check to make sure you have clean power going to the unit. Is your power connected directly to the battery, are you getting interference from another source. Your setting on the transducer should be fine especially at low speed when you are using side image or just trolling along with down imaging. You should not get turbulence interference until you start getting on plane or after you are on plane.

[RoadrashPaul]

Look up the coin leveling method as well. You need the ducer level while the boat is underway NOT while it is sitting on the trailer out of the water. That made a night and day difference for me with clean crisp images.

[n2ratfishin]

https://www.basspro.com/shop/en/bass...E&gclsrc=aw.ds

One of these make adjustments a breeze without a bunch of drilling. I used one existing hole, plugged the other and drilled one more. The. I coated the back of the board in sealer to install. From that point you are drilling into the board instead of your transom.