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Sidescan Sonar to scout ROV dive sites

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. I certainly don’t want to keep drilling holes in the boat to try different locations.

This sonar is a high resolution Sidescan (with Downscan) fishfinder with GPS.

The Sidescan has special mounting problems because it sends a horizontal beam out each side. Depth sounders and Downscan Sonar are easy to mount, but not a Sidescan…

My boat has 8" between the transom and the front of the lower unit and 24" from transom to the center of the prop.

I am looking for advice from someone who has installed a similar sidescan unit.

Hi Peter,

I haven’t worked with sidescan sonar before, but I’ve passed this along to our engineering team in case any of them have experience with this kind of mounting. Hopefully others in the community will also have experience with this that they’re able to share :slight_smile:

Following up on this, it’s been suggested I direct you to

Hope that’s helpful! :slight_smile:

Hi Peter

We have a Pioner 435 boat with a Helix 5 Mega SI that works fine. We mounted the transducer on the outside rear of the transom right at the bottom so its a few inches below the waterline, screwed into the foam filled plastic the boat is made from. We use it mainly for depth and speed as we have a Solix 15 that’s used for search and rescue as our main sonar. The image we get is fine and we’ve had no trouble with the mounting of the transducer.

The Solix transducer is mounted on a pole that is fitted to the end of a frame we built that sits across the boat. The pole rotates fore aft, in and out of the water at the side of the boat. Our screen mounts on top of the frame and at speed the transducer is out of the water and rotated down into the water when we start slow speed searching.

There are also universal transducer brackets (Brocraft Universal Portable Transducer Bracket + Fishfinder Mount or DAM Transducer Arm Fish Finder Mount Big plus others) that the transducer can be fitted to and it can be put on and off the boat as needed. For maximum efficiency, a side scan transducer should be 10% of the range the sonar is set to, above the bottom, ie. if you set the screen to a range of 60ft, the transducer should be 6ft off the bottom. This isn’t realistic on a hull mounted sonar but unless you are doing really deep searches of more than 40 to 50ft depths, you should still get a reasonable image.

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