DFF3D TM54 transducer doesn't read at speed on TZTXL 13

[Nannyslayer]

Hi Guys,

I'm not getting any bottom reading above 7 knots from my Airmar TM54 multibeam transducer which is linked to a Furuno TZTXL 13.

I have installed an aftermarket custom bracket which makes it more adjustable and brings the transducer face way closer to the transom to try find clean water. But still no improvement.

It's installed between strakes and I can't see anything else that would disturb the water flow.

Does anybody have a TM54 multibeam working at Cruise speed?

Thanks

 

[Quitsa]

That seems a rather problematic location because the layer of water flowing down the hull would create turbulence when it gets to the aft edge. How large a boat is it? Judging by the section of engine bracket that is visible, the boat doesn't have much draft, which would worsen matters once you approach planing speed.

I would guess that in the center would be a better location if you can figure out how to do it and maintain access to the drain plug. Then you would be at the deepest section of hull where the water flow would be cleaner.

Transom mounts are the only available solution in some cases but it is unusual for them to ever perform as well as a good hull mount. For example, on my inboard Diesel, the transducer for the DFF-3D is mounted in a pocket on the keel between the shaft logs. It will read bottom with very little noise on the screen at 26 kts although the PBG cannot be used above about 15 kts on almost any installation. It would be ideal if you could get a welding shop to fabricate a pocket on the keel a bit forward of the transom that would work with the trailer bunks. Probably more than you want to get into.

 

[Nannyslayer]

Thanks for the advice. It's a 7m fishing boat. The through hull with high speed fairing option didn't look very achievable given it's large size and having to fit on the trailer. So I went with the transom mount TM54 thinking the location should work. Do you think lowering it deeper would be advantageous? Cheers

 

[Quitsa]

Thanks for the advice. It's a 7m fishing boat. The through hull with high speed fairing option didn't look very achievable given it's large size and having to fit on the trailer. So I went with the transom mount TM54 thinking the location should work. Do you think lowering it deeper would be advantageous? Cheers

Putting it deeper would certainly be worth a try. I wasn't suggesting a fairing block mount, however, which makes no sense on a 7m boat and would cause you other issues. With a pocket mount, the body of the transducer is inside the hull with only the face exposed to the water. The photo below shows my DFF-3D transducer in process of installation. The angle of the picture makes it a bit hard to tell but it is right at the keel. The boat builder cut a pocket into the keel, which is a large wood beam and drilled a big hole for the upper part. Then he encased the whole thing in fibreglass cloth and epoxy and faired around the transducer face. The two blue circles are B175H and B175L tilted element conventional transducers.

With an aluminum boat, it would be a lot easier but you need someone to weld up a box for the transducer and to cut the hole.

This is probably way more than you had in mind but your DFF-3D would likely work great at speed if mounted on the keel.

One other thought would be to move the mount to the center above the drain plug as I noted earlier such that the face of the transducer is slightly below the keel. You would need to undo the bolts and swing the transducer out of the way to access the drain plug. Maybe that is an acceptable trade-off if you don't do that frequently.

 

[snappermiles]

dump it way deeper! mine reads at 30 knots but its a lot deeper than that

 

[Nannyslayer]

dump it way deeper! mine reads at 30 knots but its a lot deeper than that

Got any pictures? Is it a TM54? Yes I think I will prior to next trip out, hope it makes a difference

 

[Nannyslayer]

dump it way deeper! mine reads at 30 knots but its a lot deeper than that

This is photos after the adjustment making it lower, yet to do a sea trial to see if it's any better.

 

[Quitsa]

The transducer face is still in the boundary layer of disturbed water flowing off the bottom but I will bet you see some improvement. From the photo it appears you might be able to move it down a little farther -- I would go the maximum you can get with the mount in its current location. Good luck!