So I was trying to figure out a way to set my transducer up on my WS Ride 135.  I created a metal arm for it and it just hit me when I picked up the transducer it had a suction cup.  So, I checked under my hull and sure enough it will stick to it.  Has anyone tried this out?  Or think of any adverse issues if I do it this way, other than I may hit something that may cause it to fall off?..(I'll have it secured on my kayak and probably put something on it so the wire will stay afloat.) 

drag, snagging on weeds, breaking off or coming loose, try it tho, maybe it will work for you

Google the Duct Seal method.  Should be able to find a spot inside the hull of the kayak and place the transducer using duct seal.  This through hull method works great for me and my cheapy garmin echo on my yak...

Have you looked into something like this?  Not sure if you have a lowrance but this should work for your Ride 135 SOT.

 

http://www.austinkayak.com/products/8561/Lowrance-Kayak-Scupper-Transducer-Mount.html