I haven't seen any snapshot or recording results from towfishes (except from my own old noisy results
) at the forum so I thought it would be interesting to share some. I know how difficult it is to get something you feel worth presenting, maybe that's why there are so few results here.
I'm rather satisfied with my system now so here are some towfish images. The brakethrough came when the honored forum member Kron reported his results privately. He, and I, use 50 m shielded ethernet cable with shielded pairs. The cable is spliced in on the original HB transducer cable. (Don't use HB extension cables, the mistake made by HB to join grounds at the same connector pin will produce severe crosstalk in long extension cables.) The most obvious benefit with this cable is the complete absence of any visibel crosstalk. Noise and interference is very much better than in my earlier cable arrangements (several HB extensions and UTP cables). No cable in the world can do anything about the fundamental drawbacks with a long cable so signal level is noticably weaker but still strong enought to produce meaningful results. I think even a 100 m cable can give acceptable images provided you scan very close the seefloor/target.
First image is from a small (4 m) motorboat. It lies at 35 m and was absolutely invisibel to a hull mounted transducer.
I got an interesting image from an 8 m wreck that is almost completely covered with mud. No currents in this area. Towfish is about 2 m above the bottom. No idea how old it is. In this lake, Mälaren, sedimentation builds a 40 cm layer in 100 years, in the worst case. Depth is 30 m. When scanning close over the wreck, nothing can be seen in any sonar view. No chance to see anything of this from a hull mounted transducer 30 m above.
I hope other people will share their towfish results!