It depends on what kind of transducer your unit has.  Mine has a suction cup mount like this one that you need to remember to pull up before landing the canoe or you`ll wreck the transducer.
https://www.cabelas.com/product/Lowrance-Eagle-Suction-Cup-Kit/738118.uts

I remember Steve Molson used to use one with his kayak all the time but cant recall what his setup was.  But yeah gotta be something that attaches to the bottom of the canoe.  

There's no stopping you now Steve … 

i shoot my depth finder through the hull of my canoe,, i  just hang the transducer in a plastic  bag full of water from a thwart pointing down,, i use a" fish hawk" no bigger than a large flash light,,

I don’t know much about these depth finders but if it works like some kind of sonar device then you need need to put it in water so it can send out waves and detect the reflected waves. The waves would be transmitted through the canoe hull but I would expect that you get a fairly large reflection as well, causing some signal attenuation and perhaps a “false” reading at a depth of a few centimetres.

i use a hawk eye h22px temp gauge, depth finder,

Man i am way ahead of you guys . Bought a hummingbird decades ago , late 80's , and put it in a camera dry box. Transducer is attached to a two piece 1/4 '' rod which is then attached to a small C clamp. Just bought an 8 AA battery holder and use rechargeable batteries. This is a way smaller and lighter setup than the 2 lantern battery unit they used to sell. Get 3 -4 days use . The box is like 6 x 8 x 4 inches . The box is 100% waterproof and strong enough to be stood on.Everything fits in the dry box, unit,cable,transducer and clamp rig and battery pack
Only takes mins to tighten the c clamp over the gunnel ,plug the wires in and you're in business. Take it everywhere on canoe trips through Algonquin.One troll around a lake and i know more about holes , drop offs etc than if you fished the lake for 20 yrs.Also shows fish icons < 1 lb, 1-2 lbs and >3 lbs .

Last edited by Antman (1/20/2020 9:34 am)

I don't but i will take a pic for you . I will also include a second setup that uses the cheap chinese unit mentioned by Swift fifteen. It is even smaller and lighter and uses some telescopic antennae like rod instead of the 2 piece 1/4 '' inch steel rod.
These units allow me to stay in the 12-15  ft depth range i like and hence saves me on snagged lures . With a ball bearing swivel its getting darned expensive to snag up.

That's awesome Antman!  Thanks for sharing those pics.  I have the exact same fishfinder (Humminbird) and I have a Pelican Case about that size...I might do something similar!  The AA's work ok eh?  Looks way lighter than the 2 massive batteries I have for mine!