-- Last Updated: Nov-07-11 11:07 PM EST --
....... go on the center line , goobs .
Mount it off to the side of the center line some (couple inches , or more). 5 min. epoxy , the double tubes in hardware store that look like a syringe , 1 to 1 mix . Making it perfectly level is not really that critical because if you think about it the boat is constanty rocking and bouncing anyway . Flat to the haul is good enough .
If it were me I'd epoxy it on leaving a thick enough bed of expoxy (say a popsickle stick gauge for thickness) , so I could send a thin fine blade saw underneath to remove it later if desired . Just don't add any filler to the epoxy . Remember , sanding down the face of the tranducer is an OK thing to do . Just use X-fine like #400 - 600 to finish up and buff .
To make a nice little neat job , just cut a little form out of popsickle sticks . Fit them to the outside of the transducer , then remove 1/32 from each . When putting the form together to make the rectangle just put the slightest dot of glue in the joint , not full joint coverage , just enough to hold it together temporary . The form sets under the edge of the tranducer 1/64 all around when you set the tranducer onto the form with epoxy filled in the center (slight bubble up of epoxy). Gloss paint the pop sickle stick form and wipe a super thin coat of oil on the inside edge so you can break it away , the wood will seperate from the epoxy that way . Have some acetone and a rag to wipe away the excess that will squish out . Hold tranducer down snug with your hand for 5 mins. while epoxy sets up . Break away the form and put a bead of silicon or putty roll around perimeter .
Tranducers on boats that are left in the water all the time need to be cleaned and sanded as general maintenence , because if not they give lousy static clutter readings when they get surface crud build up and scratches .
I don't use sonar on my canoe , but you can bet I'd mount thru hail shooting just as described if I was going to . Always sonar on the bay boats and any Jon though