Another transducer mounting question, sorry!
So I am setting up my Elling for next season and I need to mount the (very large) 3 in 1 sidescan transducer for my HDS unit. I've realised that on this "cat like" hull, the transom really isn't low enough to use the same solution that I had on the Honwave. Not only would the transducer perhaps be too high above the water at speed, but worse is that the tubes and the central "sausage" keel would likely block much of the sidescan (being able to view and record high quality sidescan is very important to me). I also had some issues with the engine blocking sidescan to port on the Honwave, because of the distance that the transducer protrudes from the transom.
It seems like the guy in this video
had similar issues on his Elling, and came up with quite a neat solution (see 10 mins on in the vid, or pics below). Transducer is mounted centrally and reversed (front/back), so that it sits directly underneath the sausage. It has a totally unobstructed view, and hopefully gets clean water when under way. The sleeve arrangement glued to the underside probably makes this rather secure also:
I want to do the same, but I've got a couple of issues. 1/ the transom plate is much deeper on my version of the Elling, so I can't fit one of the borika mounts between bung and transom plate and 2/ I don't think I quite have the clearance engine/transom to allow it in any case (I need to check this).
My proposed solution is to mount HDPE blocks, one each side of the bung hole. Then make a sort of T section, probably out of 4-5mm alu bar, which attaches to the blocks and also the transducer. Transducer then slots into a simple sleeve of PVC that I glue to the sausage. This should be a very low profile mount.
A very rough idea of the mount:
A simple, open fronted sleeve that is glued in such a way to be snug to the transducer but still allow removal:
How best to attach the aluminium T bracket + transducer to the transom blocks. This has to be tooless and removable. One idea I have is to get some threaded brass inserts for the HDPE, and some stainless thumb bolts. Should work? I worry it won't be secure enough and may work loose through vibration, but is there a better way? It needs to be fairly low profile, also.
I am hoping I can arrange things so that the transducer is snug to the underside of the keel, and within the sleeve. If this works out, I think it should be fairly secure and not kick up a lot of extra spray etc. Any thoughts? If water can get in at the top, I imagine that may apply a fair bit of pressure when underway which might pop the transducer out. Perhaps it is worth trying to craft some sort of fairing at the front? Followup question, how will the sleeve behave with no transducer mounted?
Open to any bright ideas!