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I just upgraded to a Garmin chart plotter and with it came a GT23 transom transducer but from my understanding those are not meant for sailboats, so instead I picked up a GT8HW-IH (in-Hull) transducer. The boat is in the water and the current transducer which is a thru-hull, is in the V-Berth but I am not sure if I should install the new in-hull transducer next to the old thru-hull?

Where would be the best location to install it? Some people have said to install it in the bilge, but since my bilge is right above my keel, would that throw off the transducer? Or would it be fine since its a centerboard keel?
 

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My ‘74 I28 Mk4 (CB) has a well under the aft port “bunk” in which I set my Garmin transducer....filled the well with water and the transducer shoots through the hull with exactly the same depth reading as over the side. The well has a gasket seal and screwed down cover.
 

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I just upgraded to a Garmin chart plotter and with it came a GT23 transom transducer but from my understanding those are not meant for sailboats, so instead I picked up a GT8HW-IH (in-Hull) transducer. The boat is in the water and the current transducer which is a thru-hull, is in the V-Berth but I am not sure if I should install the new in-hull transducer next to the old thru-hull?

Where would be the best location to install it? Some people have said to install it in the bilge, but since my bilge is right above my keel, would that throw off the transducer? Or would it be fine since its a centerboard keel?
To me the best location is forward of the keel as close to the centerline as possible. But you need to know what is the maximum deadrise angle it can accommodate.
 

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A chunk of plastic pipe cut to angle of deadrise .Glue to hull, fill with water, dunk the transducer .cut a wire slot in the cap. If pulse frequency is the same as the Garmin the old transducer could carry on??
 

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Best location is centerline in front of the keel. You want the depth reading in front of your centerboard, not under it.

You could use the transom transducer to shoot through the hull. Bed it in silicone making sure there are no voids in the silicone. Your temperature reading will wonky, but it will work just like the in-hull. Same wigit, different case.
 

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Once you've picked your spot you need to know if the transducer will actually work there. Any core or air bubbles in the hull layup will affect it. Fill a zip lock bag with water, press it to the hull and press the transducer to the bag. If it works there you can go ahead and glue it in. Have to do the test in the water of course.
 

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Test multiple locations first before you glue or epoxy anything. Put the transducer in a plastic bag filled with water. Place the bag and transducer in contact with the hull and see how well it reads. In-hull transducers are designed for small runabout power boats with relatively thin hulls. They often don't work well with the thicker hulls of crusing sailboats. If your hull is cored, it probably won't work at all.
 
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