Author Topic: Mounting a Sidescan Transducer  (Read 248 times)

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Offline ROVman

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Mounting a Sidescan Transducer
« on: October 02, 2021, 08:22:26 PM »
Thanks for this Forum.
I am looking for advice on mounting the transducer for a Humminbird Helix 7 Mega SI GPS G3 on an 18ft Bowrider with Mercury 4.3L I/O. Has anyone done this successfully on such a boat? Photos of your installation would be very helpful. I don’t want to buy this Sonar without some idea of how useful it will be.
My application is to look for interesting places to dive on with my ROV.
The Helix Series Operations Manual and the Getting Started manual say nothing about mounting  the transducer. That information is in the Transducer Resource Guide.
The manuals can be found here:
https://www.humminbird.com/support/manuals
Scroll down to Transducer Manuals to find the Resource Guide.
Page 7 of the Helix Series Operations Manual has a useful list of Humminbird models.
Page 256 tells you which transducer is used for the Helix 7 Mega SI GPS G3.
The Helix manual is annoying because it covers all the different models and many of the 330 pages apply to other models. Apparently no one provides nice manuals suitable to carry with the devices. Depth sounders and video cameras, for example, are too complicated to use without a manual but then you have to carry them. Printing a copy winds up with a sizeable binder. Staples will punch the pages for a spiral binding with cover sheets that is the best to be expected. A manual on a ‘phone is useless in my opinion. I don’t know if it is on the Sonar but I suspect not.
I gather the Side Imaging is best used at slow (< 5 mph) speeds.
I am considering mounting the transducer beside the hull drain hole at the bottom of the V hull. It would be 8” from the front of the lower unit and 24” from the center of the prop. Has anyone tried this? I don’t want to start drilling holes to find out it does not work here. It could also be mounted further away toward the Chine but I’m not sure how much of the hull would be seen. The beam may be narrow but it will not be perfect enough to shoot through the 8” gap without scattering off the hull and lower unit.
Another option is to mount a simple Depth Sounder (Down imaging Fishfinder) in the boat and deploy the Sidescan transducer on a long arm, well away from the boat, to be used at slow speeds. i.e. two different Sonars.
I am fitting my ROV with the BlueRobotics Scanning Sonar for collision avoidance and to navigate close enough for the camera to be useful.


Offline Rüdiger

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  • Software: DrDepth BT+SS
  • Accessories: Towfish and Towcam
Re: Mounting a Sidescan Transducer
« Reply #1 on: October 03, 2021, 05:17:07 AM »
Hi ROVman

Welcome to the forum :)

Basically, the encoder must be mounted in such a way that it has a clear "view" on both sides. Turbulence caused by steps or the drive should also be avoided as far as possible.
Si quality and boat speed are inversely related, the best Si results are achieved with the slowest controllable speed.
I also installed the transducer on a boom and only used it when needed on my first boat so that I could see past the outboard motor.



mvh Rüdiger
Sorry
English is not my first language !

German Forum
Side Scanning and more
https://www.sob-international.com/

Offline ROVman

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  • Location: Deep river, Ontario, Canada
  • Posts: 2
  • Unit(s): Helix 7 Mega SI GPS G3
Re: Mounting a Sidescan Transducer
« Reply #2 on: October 03, 2021, 12:06:03 PM »
Thanks for the reply. It looks like you mounted your transducer to a towfish?
I see some examples of mounting here: https://www.humminbird.com/support/faqs/SI_Transducer
but none with an Inboard/Outboard. These are photos of my boat which has 8" between transom and the front of the lower unit.
There is 24" from transom to the center of the prop which is Right Hand rotation.
Does it really matter if the transducer is mounted on the left side of the lower unit? The prop disturbance is way behind it.
Is 8" gap enough for the side scan beam to clear the lower unit?
Intuition says to mount the transducer above the horizontal flat closest to the center of the boat. Is this a poor choice?
The Side Imaging will probably not work well at 30mph but will the Down Imaging work or do I need to install a second Depth Sounder?
Will the Helix 7 accept a high speed transducer as well as the SI/DI transducer?

Offline rnvinc

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Re: Mounting a Sidescan Transducer
« Reply #3 on: October 03, 2021, 09:19:11 PM »
The SI beam covers from the water’s surface to past vertical under the boat so there will likely be blockage from your inboard  ...

There is the option of installing a second SI xducer on the other side of the inboard using the 9 M SILR Y cable :
https://humminbird.johnsonoutdoors.com/accessories/cables/9-m-silr-y-helix-side-imaging-left-right-splitter-cable

And there is also an option of an additional 2d xducer for high speed digital depth using the 9 M SIDB Y cable :
https://humminbird.johnsonoutdoors.com/accessories/cables/9-m-sidb-y-helix-side-imaging-2d-sonar-splitter-cable

Rickie


Offline Rüdiger

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  • Joined: Feb 2011
  • Location: Hjältevad Sweden
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  • Unit(s): 898 CX SI ;EAGLE 500CDF
  • Software: DrDepth BT+SS
  • Accessories: Towfish and Towcam
Re: Mounting a Sidescan Transducer
« Reply #4 on: October 05, 2021, 04:30:50 AM »
Hi ROVman

I have two transducers, one on the towfish and the other on a swiveling boom (you can see it in the background).

mvh
Rüdiger
Sorry
English is not my first language !

German Forum
Side Scanning and more
https://www.sob-international.com/


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