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Old 10-12-2014, 09:42 AM   #18
Tony B
Tony B's Avatar
City: Joe Wheeler State Park, Al
Country: Cruising/Live-Aboard USA
Vessel Name: Serenity
Vessel Model: Mainship 36 Dual Cabin -1986
Join Date: Jul 2011
Posts: 1,250
I decided to get the Humminbird 346C Di Color Fish/Depth finder which can be inside-the-hull mounted. The instructions for installation are the same as I have done over the last 20 years or so and I'm good with that.

Lessons learned: Always test the unit BEFORE installation even though you never had a problem installing them in the past. After running the transducer cable from the bilge to the flybridge, you really don't want to take it back out again because the transducer didn't work.

I have 2 tests I used:
Test 1). Rough wire the Control head in its approximate permanent location, plug in the transducer and throw it overboard about a foot or so below the surface and turn on control head. It should read the approximate depth with no flashing lights. Because the transducer is moving around and pointing every which way, don't expect miracles. You just want to see if everything APPEARS to be OK. I left mine overboard for several hours, turning it on and off again.
Test 2). Move your whole operation to the bilge. Mark off the location where you want to permanently mount the transducer. In my case, the hull has exposed roven woven fiberglass and did not give me a flat surface. I used a multi-tool to sand the paint off it and then mixed up some epoxy and spread it over the area trying my best to flatten out the surface by filling it in. Easy enough with a 4" wide putty knife. Only took a few minutes. You must have a good surface to work from.
That evening, the epoxy cured and I sanded lightly to make sure surface was flat.
Temporarily get 12V dc to the control head and plug in the transducer. Now place the transducer inside a sandwich baggie partially filled with water. It only has to keep the bottom under water but to make sure, I added enough water to submerge the entire transducer. Set the transducer in its proposed permanent location and use 2 sandwich baggies half filled with sand to hold it in place and weigh it down.
Now turn on the unit and Voila! This will show you exactly what you will see when unit is permanently epoxied in place. If all goes well, dry up the wet transducer and permanently install.

I know this sounds like a bit of overkill and this is the first time I have ever gone through this much trouble. I really, really did not want to run the cables and then remove them again due to a faulty transducer a second time.
Cruising the Eastern U.S. Inland Waterways and Gulf Coast. Presently on the ICW in Louisiana and heading Back to Texas.
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