Topic: towfish image at 455 and 800 khz

[abraquelebout]

just 2 towfish images of the same wrek
one at 455 khz and the second at 800 khz

[abraquelebout]

to compare the same

[Rickard]

Nice and interesting! I have been wondering how much I miss with my 981, since it cannot use 800 kHz. I don't think the difference in detail compensates for the loss in range in your images. I would think 800 kHz is impossible to use with 50 m of cable. The loss in signal level is large because of the cable, and in combination with short range from the beginning I think very little can be seen. Has anyone tested 800 kHz with a long cable?

Rickard

[abraquelebout]

today i connect the probe to 50 m of cable
the next navigation  can  be answer to the question
wait and we see

[deltadiver]

Thank you for posting. This is interesting.

 

[keizerh]

time for 265 kHz as well
hendirk

[Jolly Roger]

I hear you Hendrik    !

But first I need to get the boat in the water. I doubt that I can get the fish and 50 meter of cable towed with the dinghy.

Abra, nice shots! It's really nice to see the difference.

Regards / Harry

[abraquelebout]

hi rickard
towfish with 60 m of cable !!! (196 feet).
i've got the 455 khz and 800 khz. the deph, t° and all information
in this image the towfish is at 6 m deph and 50 m of the ship, there's 10m of cable on the boat but the  weather is so bad (1,50 m of wave an 15 knots of wind) the ship is at 3,7 knots
i join image.
i'm waithing better condition to go on wreck site!

[Rickard]

Congratulations!!

What a relief to see how well the cable design works on other systems! I think you have at least the range I got with my cable. I can see how choppy the conditions were that day from the surface reflections. Really encouraging for all of us who try to get deep!

I look forward to hear and see more from your scanning!

Rickard

[easysailor]

Niece scan..good detail. What type of able are you using to keep a strong signal? How are you holding  it to the boat  to keep a nice curve bend to the cable and not pinch it?

[abraquelebout]

the cable is an clear signal cable who serve in aeronautique machine tool to transmit data
one my friend give me 85 m but i think it cost 7 € / m.
on boat whe make wide bucle for the cable, there's 60 m (196 feet) of cable and there is no lost signal.
my towfish is made in 1,5 m aluminium tube and composite for the fin's, there 2,6 kg on nose
i join a image of the towfish.
for better deph i hope whe take ballast on a nother rope and a  hydraulic winch.
whe are waithing better condition to use this system.

[Rickard]

You say "signal cable", is it an ethernet cable or some other type of  cable? I use ethernet cable for my fish and I think the result is about the same you get.

Rickard

[abraquelebout]

it's an other type,it use in industry at sogerma and aerospatial, i'm not electronician, when i speak to my friend who work in these industry he said me "ok, i have one cable , i'l give you"
it conduct 300 v
awm style 2464 80°c 300v vw-1
for me it's a "charabia..." i hope that it talking to you
it's stronger than an ethernet cable and it's working weel.
there's 2 shield pair, a ground and shielded tress, and aluminum foil protect

[easysailor]

Well lay-ed out system. How do you pod the connections to the transducer? How deep can you get your fish with the 2.6 kg weight? On your larger boat how will you keep the cable from  breaking/pinching when you set it over the side? Picture attached of my old setup. What are the fins made of when you say composite? Thickness? Height?

[abraquelebout]

hi
i join you picture  of conection, i soldering  all the wire and i insulate them with 2 thermoductable girdle by wire on the transducer (for the pressure) and one on the unit. for the watertigltness i use 3M mastic tape
my fins are in  sandwich alu - resin 3,2 mm, i join you the model
the aluminium pipe 1,50 m and 56 mm diametre
when whe use a small boat on river at 2 kns the towfish dive with a small rope and sink easily.
when whe use  the 9 m woden boat hardly to put into gear whe go at 3,7 kns
the rope is so heavy like the picture an whe  put the rope and cable on deck like picture there's no problem
for more deph whe use weight on a nother rope and hydolic winch

[abraquelebout]

more pictures

[Rickard]

Nice!

I removed my first reply on your wiring diagram when I realized I had mixed up some of the wires in the transducer cable.

You have your own solution that looks like the Humminbird original wiring at first glance, but then you combine the downward 200/87/50 kHz with temp in a twisted pair and both SI channels in another twisted pair in the extension. I would have expected the combination of SI channels in the same pair would cause a maximum of crosstalk between the SI channels. Obviously, this works great and perhaps I have to change my opinion which states that the SI circuits should be kept within a pair. Do you have a rationale for the wiring design?

Rickard

[abraquelebout]

hi rickard
for the wire i hope that: the red conector must be the t° because when i test it these a resistance, in my head i prefere connect the 800 on the same pair and the other one one other because for scan, it's more important to have a good signal in 455 - 800 khz. I bet that there's no interference...
i accentuate the connect to ground in soldering all of them to the plait of ground.
i hope that my cable must be longer than 60 m, in the begining it whas at 85 m, but for us it make so long, i cut it at 55 m and soldering it to 6 m transducteur cable