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I bought a little Sitex and a thru-hull tilted element transducer for Crows Nest. Install instructions say nothing about a backing block. Basically, make the hole, install the ducer with the rubber washer and nut on the inside with sealant, and go. That's also the way that Doug had a little hummingbird tilted element ducer mounted and it worked fine and never leaked. There's nothing really sticking out underneath the hull that could get hit, and only the rest of the ducer housing above hull, so I'm not sure I need to spread the load like I'd do with a thru-hull for a water supply or something.

Should I install per instructions, or make a backing block? I'm thinking that I'll just follow the instructions, but thought I'd ask for the group's wisdom.

Thanks-

John

Right or wrong that's how I installed mine.


My thought pattern same as yours...nothing protruding to hit requiring re-enforcement, angle is already set...adding anything seemed to complicate simplicity of design.

When I redid all my thru hulls the backing blocks were mostly rotted. I believe the hull is thick enough to do it without. I did not use any block on my ducer either.
The only caveat was I had to do some grinding because the thickness of the hull was not even as it went away from centerline. That caused the nut to not seat firmly, it was a bit cock eyed. Ground it even and smoov, applied 5200....Done. Having a ducer with temp is nice!

Thanks. It's installed and I followed both of yours advice.

JohnF,
I always used a backing block when installing X ducers and thru hulls. I used to use 3/8''to 1/2" flat stock fiberglass that came off the flanges when we pulled the 34' Legend boats out of the molds. The way I look at it, it just gave the nut some more to grab on to and spread the load when it was being compressed. I also used nothing but life caulk for bedding and never had any leaks. Over the years I must have installed 500 thru hulls and X-ducers when I was installing electronics back in the 70's and 80's. Back then we used the fiberglass stock that came out of the hole that was drilled for Data Marine displays for the backing plates.. All my thru hulls and X-ducers in the 1961 31 Express Vizcaya were fiberglass backing plates, the old plywood ones were all just rotted away after 40 something years. The new owner will never have to do anything to the fittings ever.
I miss being without a boat but after this next knee surgery I am going to start looking again.
Pete Fallon