Author Topic: Towfish – The Danish edition  (Read 3658 times)

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Offline Kenneth W. Sørensen

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Towfish – The Danish edition
« on: October 10, 2016, 01:35:40 PM »
I finally finished my Towfish project. Although there were some startup issues, I am very happy with the result.

The body is made of aluminium and the nose is stainless steel. I mounted the transducer inside the body to avoid the transducer to act as a hook if I get to close to the bottom. The cable is a standard 50m Cat7 cable which I manage to fit inside a PVC hose after a little struggle.. Along the cable I have a 4mm wire with a D-ring for every 5m.

I have only tried it twice, but so far I think the result a OK. The attached screen dump is not the best shot, but the rest of the recordings I have only show sand and stone ;-)

Thanks to all of you for the inspiration and wisdom that lies in this forum.


Offline Rüdiger

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Re: Towfish – The Danish edition
« Reply #1 on: October 10, 2016, 11:58:29 PM »
Hi Kenneth

Congratulations, very good work. :)
The idea with the inside transducer had no one here yet.
Good luck with your new "toy".

mvh
Rüdiger
Sorry
English is not my first language !
http://de.groups.yahoo.com/group/SOB-International/

Offline newkid4si

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Re: Towfish – The Danish edition
« Reply #2 on: October 11, 2016, 01:41:58 PM »
Great design!  The "inside transducer" is a really neat idea.  How did you prevent water turbulence in the area where the transducer meets the outside of the tube?

         Mike

Offline abraquelebout

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Re: Towfish – The Danish edition
« Reply #3 on: October 12, 2016, 09:19:13 AM »
it's nice to see another towfish, keep us informed, it seem's good

Offline Kenneth W. Sørensen

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Re: Towfish – The Danish edition
« Reply #4 on: October 14, 2016, 01:36:45 AM »
Hi
I don’t think the turbulence is a big problem because the transducer is in the same level as the bottom of the pipe. But it is only my assumption. If it becomes a problem my plan is join the sharp edge on the pipe with the transducer.

How can you “See” turbulence?

I do however get some white “snow” on my side scan when the fish is moving up or down in the water when I change the speed of the boat. As soon as the fish is stabilized the white “snow” disappear.

Right now it’s too windy to do any sailing. But according to the weather forecast it should be possible to do some scanning next week. I will keep you posted and hopefully I will upload some fine screen shot.

Offline Rickard

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Re: Towfish – The Danish edition
« Reply #5 on: October 14, 2016, 02:21:27 AM »
Hi Kenneth and congratulations to your well built towfish!

Water turbulence is not an issue with these systems. I have never seen any effect of that. Sound speed in water and the way the transducer transmits and receives sound makes that unlikely. I think it's more likely your "white snow" is caused by interference from some electric device in your boat, like the alternator or the ignition system.

/Rickard


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