my ocean kayak has a scupper hole in the rear that is made to hold a transducer. it is egg shaped. i don't use them because i don't troll with it. i cast towards shore always.
i read they are expensive to get the ones that fit that design. i think it was 250$ and not a brand i would use either.
maybe think of how would it benefit you to have one on it or not. i have a marcum lx9 that is designed for open water too, but i always cast towards shore even in my boat and that has two sonars on it. the only reason i would turn one on it to get the water temp.
if you think you want it, see if your ducer is small enough to have most of it in a scupper hole first. if not then hull mount it. the ice ducers are limited and won't see far away tho, so you might prefer an open water ducer that does. cone angles are what your looking at next. open water uses 60 degree cone or more.
people use various adhesives for hull mount and some just keep a wet wash cloth under it. marine goop is one of the adhesives and i think clay was another. just use a semi permanent adhesive so it can be used on ice or if you buy a open water it can be removed if you upgrade your yak.
it has been talked about here and mf so try the search engine on both sites for more info.
here's more info on the web
http://www.fishnyak.com/sounder-to-prowler-13.htmlhttp://store.oceankayak.com/products/909695/Transducer_Kitshttp://www.austinkayak.com/products/2625/Humminbird-Transducer-for-Ocean-Kayak-Fishing-Kayaks-XTH-9-20-P.html
