Transducer inside the bilge of an aluminum boat?

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SAABologist

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My garmin transducer is working fine trailing off the starboard side of the transom.

But I have seen a lot folks driving fiberglass pangas in Mexico simply place the transducer in the bilge and it works well. This makes me want to try it on my 16' aluminum MirroCraft. Has anyone viewing this post tried their transducer in the bilge of their tinny? Depending on what I hear back, I might give it a try and see how it works.

Thanks,
 
They can shoot through fiberglass as long as there is no air pocket. I had one in the bilge of my 20' bowrider. When I had it on the stearn, it would kick-up at high speed. As far as I know, can't shoot through aluminum, but I can't say I have tried it.
 
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Some have done it with aluminum but loose of signal does occur. It really weakens the signal so most don't bother trying. The transducer is set in a pool of epoxy in the bottom, no bubles can be in there. But the aluminum reduces the signal still. Might get away with a depth reading but finding fish probably wont happen.
 
Surprised that you would get any reasonable signal thru the alum hull.

You can test with water in the hull or with silicone grease. On my bowrider, near the centerline the fiberglass is thicker and got noticeable weaker signal. 10” off centerline was good but have to adjust for angle of hull. Test at speed and depth before going to epoxy.

If you have side imaging, it will not work thru hull, and will need a splitter cable and separate 2D transducer.

If it is working fine on stearn and not creating issues, I’d leave it.
 
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If it's kicking up, you may have the front set too low or the pivot bolt is too loose.
It definitely will not show side imaging in a shoot through configuration.

You can silicone a plastic ring, cut from a detergent bottle or something like that, to the inside of your bilge. Fill it with water and drop in your transducer and see what happens. It might work.

But I would fix the transom mounting issue myself.
 
If it's kicking up, you may have the front set too low or the pivot bolt is too loose.

But I would fix the transom mounting issue myself.
This was on my bowrider that I sold last year. I tried multiple angles and heights. Any higher than I had, would loose signal. This was a Humminbird 2D transducer. It didn't swivel up, it pops out of the mount. Its a "protective" feature in case it hits something. It would pop-out at 45mph or higher.
 
They sell a transducer specifically for that. I've heard they're not as good as one on the exterior, and I think you can't use side-imaging with them. I don't know much about the subject. I'm planning to buy one to use in the back of the boat just to monitor depth and locate structure. It's called Alumaducer I think, and them for different brands of fish finders I believe.
 
If it's kicking up, you may have the front set too low or the pivot bolt is too loose.
It definitely will not show side imaging in a shoot through configuration.

You can silicone a plastic ring, cut from a detergent bottle or something like that, to the inside of your bilge. Fill it with water and drop in your transducer and see what happens. It might work.

But I would fix the transom mounting issue myself.
Had a friend do something similar and was just using his old ice fishing rig. Wouldn't handle much motion, slow troll at best. He silicone a toilet plunger to the bottom of his aluminum boat and cut the plunger such that it had a grip on the transducer. He kept a bail sponge that he used to put water in the plunger. I think permanent epoxy would have been better.
 
Can't figure where this idea is coming from that ultrasound won't go through aluminum. It is solid, no gaps, so should work right through it better than it goes through the water itself. No side imaging I can see maybe, but some of these systems are amazing with their math so I would not say impossible with newer systems. Ice fishing we carry extra water in our bait so that we only need to drill down into the ice enough to create a shallow to hold some water then set the transducer in it. Works though the thickest ice I've ever been on. Even more important these days with electric ice augers, don't want to waste the energy in most cases.
 
why wonder? SOP for installing a shoot thru transducer is to test it before epoxying down. Use a wax toilet ring or modeling clay or something like that to create a Pool inside your hull where you will put the transducer. Fill it with water. use a sand bag or a brick or something to hold the transducer agsint the bottom in position, and test it. You will get more or less exactly the performance you will get if you do a good job epoxying down (ie being careful not to trap air in the epoxy or under ducer). I've never tried it in an aluminum, but some people say they have used the standard transducer with good success as a shoot-through. When you find the best location, then you thoroughly clean before epoxying it down.
What I have been told is that you can expect worse sensitivity than if it was on a glass hull or in the water, and that the biggest issue is flexing in the aluminum potentially separating the transducer from the hull over time, potentially fairly quickly on a lighter-weight hull. And side imaging/down imaging is a total no-go if you want the resolution you expect from those types of sonar.
 
I've shot through alum and kevlar rental canoes using Duct Seal from Menards. A brick of it costs $3. Just put a glob down and squash the transducer on top of it. Sticks good and comes out easy. Before I tried that I stuck transducer on the side with a rubber sucker. In the way and always falling off. Didn't see any difference in sensitivity shooting through the hull.
 

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