I'm taking my SR Q17 this weekend and the in-hull option might work. I've always had better luck re: functionality with having the transducer actually in the water. My solo Northwinds has factory guide skid plates as well as the foam core which makes it hard to locate a flat spot on the boat's inner hull to place the skimmer transducer.

I like the rail site's option. I'll have to look at that as well. Still pondering options......

I have a SR 18.5 and I am able to shoot thru the hull without issue.  What I do is, I have a piece of closed cell packing foam about 4" x 5" x 1" that I traced the transducer outline on.  Then I cut a hole slightly smaller than the outline so I can push my transducer into it and it is firmly held in place and upright.  I then silicone the foam in place and it allows me to easily remove or install the transducer with just a splash of water to maintain the signal.  I have found the silicone sticks better to the canoe than the foam, so I drilled holes in each corner of the foam and injected silicone to make a soft rivet to hold it in place.   The silicone does come off the canoe with a gentle scrape from a plastic putty knife, leaving no marks.

DB,

What kind of canoe do you have?

I have a Bell Magic solo and the "shoot thru the hull" method using a foam cutout in my bow works like a charm.

However, I have tried to make the "shoot thru the hull" method on my Wenonah MN II tandem work and I cannot get it to shoot without all kinds of interference. I have placed the transducer puck all over the floor in the bow to no avail. I know there are foam ribs across several areas in my skin coat Kevlar and I was sure to stay away from shooting thru foam core.

From your pic ...it looks like you have a Wenonah canoe ... and it is working for you ?

I am not sure if a MINNESOTA II has some construction material that may be blocking the sonar waves emitted from my Lowrance X-4 depth finder. 

Anyone know about the construction material of a 1992 MN II Kevlar skin coat ?  I thought a 1996 Bell Magic would have similar construction material as a Wenonah  MN II.

H&D Walley13
It is true that a transducer does not shoot through foam care well at all but you can go around it.  NorthStar Bell canoes have a cut off diamond shaped foam core in the floor of the canoe.  I have a NorthStar Polaris Bell Magic with the same floor as the Northwind your Bell Magic and I mount the transducer behind the back seat just off of the foam core.  Works well. I use plumbers putty and it takes me about 10 minutes to switch it from one canoe to another. It sticks well enough that it has never fallen off in many trips to Canada and back but it is easy to remove to put in another canoe.
MP

All good ideas. I have to figure out how to navigate the factory skid plate and the foam core construction.