Author Topic: Towfish results, various depths, same wreck.  (Read 5737 times)

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Offline Rickard

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Towfish results, various depths, same wreck.
« on: May 18, 2010, 01:32:01 PM »
Hi,

It's extremely difficult to add images without faults so I just test this time with a few images from the same wreck.

Well, now the images are there, but not in the order I planned. Second image was intended to be the last since it was from the last run. The idea was to show how the towfish has revolutionized my scanning!  :) :) I added one image, but then the order between images and text changed unexpectedly.

Rickard

First image shows a barely visible wreck when the towfish is pulled at about 5 mph. Then the fish runs 25 ft down.
ila_rendered

Here the fish is towed at 1,5 mph, 3 ft above the highest part of the wreck.


ila_rendered

This was my first contact with the wreck. The surface reflections helps to give a sense of where the fish is located relative the surface and the seafloor.


The image below was arranged to give a sense of depth conditions. The white line indicates the trajectory of the towfish.
ila_rendered
« Last Edit: May 27, 2010, 11:10:41 AM by Rickard »


Offline keizerh

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Re: Towfish results, various depths, same wreck.
« Reply #1 on: May 18, 2010, 02:07:36 PM »
Wow,

20 metres under sea level.
A few metres above the wreck. Tried this with my sportscan and lost it (but got it back)

Have to try this with my SI as well

hendrik

« Last Edit: May 18, 2010, 02:15:37 PM by keizerh »

Offline Jolly Roger

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Re: Towfish results, various depths, same wreck.
« Reply #2 on: May 18, 2010, 02:27:25 PM »
150 feet of cable Hendrik!

I hope we can get the same results  ;)

Nice shots Rickard, congratulations!!
Regards / Harry
YES,......
WE SCAN!

Offline Rickard

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Re: Towfish results, various depths, same wreck.
« Reply #3 on: May 19, 2010, 04:08:17 AM »
Thanks,

Yes, the cable is 150 ft in all three images. The signal gets weaker, of course, but it's still possible to see structures 75 ft below.

I added some lead and now the fish weights 10 kg (20 lb). This is near the limit for handling the fish with your bare hands. I can run at 2 mph with 120 ft with cable out and the fish at 90 ft depth. My waters are no more than 135 ft deep so now the system fulfils all my wishes on depth performance and scanning speed.

I use a regular downlooking sonar to get some lookahead that warns for obstacles.

Rickard
« Last Edit: May 19, 2010, 04:09:58 AM by Rickard »

Offline keizerh

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Re: Towfish results, various depths, same wreck.
« Reply #4 on: May 19, 2010, 10:17:05 AM »
My Sportscan was about the same weight.
Also  50 metres of cable and I could get it down to 25 metres in salt water.

Harry should connect the towcable to a downrigger connected to another head unit :-)
The the fish will be pulled up before an obstacle is hit
hendrik

Offline abraquelebout

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Re: Towfish results, various depths, same wreck.
« Reply #5 on: May 25, 2010, 03:08:25 PM »
hi rickard,sorry for my inglish, i eard 1 thing wen i was young "take the door!!!" :-X
french towfish in progress
, this joins 2 pictures, 1 of the surface and the other one at 5 m of the wreck.
We are going to connect the probe to the cable for more deep.
UnitÚe on 1197 si, salt water

Offline abraquelebout

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Re: Towfish results, various depths, same wreck.
« Reply #6 on: May 25, 2010, 03:17:52 PM »
sorry the second picture is not  good
now the good picture

Offline Rickard

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Re: Towfish results, various depths, same wreck.
« Reply #7 on: May 26, 2010, 09:54:20 AM »
Hi Abra!

Really nice images! The second, good one, demonstrates clearly what you can gain from getting closer the seafloor. Shadows become more defined and detail is better. The seafloor seems to be solid rock. Do you know the identity of the wreck, it looks very old?

Regards,
Rickard

Offline abraquelebout

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Re: Towfish results, various depths, same wreck.
« Reply #8 on: May 26, 2010, 10:17:35 AM »
yes whe know the name of this wreck
Eyriaud des vergnes he sunk in 1892, but when i see the film on yellowfin, i find a nother wrek at 80 m of the ship... a dive on this structure may be interresting. i hope that we go to dive on this week.
i join you a picture



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