Does anyone use a depth finder on their canoe or kayak? Which one do you recommend?? Are the hand held units any good? Can they shoot thru a plastic hull as advertised?
Don’t use one
in my canoes, but my prior sailboat had the transducer mounted inside the hull, and shot a signal through about an inch of fiberglass.
yes
I had one mounted in my fishing kayak and it worked fine. I used a Humminbird at the time. My next fishing kayak will be rigged with an Eagle Cuda 168 because it was cheap. Dont get too expensive and make sure it is waterproof. I used polyurethane caulk/adhesive to seat the xducer. It will stick to poly but takes a week to dry. Make sure there are no air bubbles.
Haven’t tried to shoot through plastic,
…but I bet it would work. Maybe you’d lose a bit of sensitivity. I assume this is for fishing, and so I personally wouldn’t be too keen on a hand-held unit. You want to be able to scan for drop-offs or weedlines while you are paddling, rather than paddle, stop and shoot, paddle, stop and shoot… “damn, too far, the drop-off’s back there someplace”… Same goes for fishing as you drift with the wind. You want to know what’s beneath your boat without having to put down your fishing pole and pick up the sonar, only to find out you drifted off your spot and have no clue how far away it is now.
I don’t know much about all the choices available, but I have a Vexilar “Boundary Waters”, which is just a portable version (no mounting brackets, no need for an external battery) of some identical unit with another name. I think it’s superb for being so small and lightweight. For what it’s worth, the suction-cup transducer mount isn’t as much of a pain as you might expect, but plastic is pretty dense and I’m betting the signal will shoot through the hull well enough. On a composite boat, I temporarily glue a short little section of PVC pipe to the floor and fill it with water, and set the transducer in there. It works fine that way.
mtnesters… what in the world would…
…you use a depth finder for in a kaak? Can’t be fishing, because there is a separate board for that. Honestly, not being flippant: why the depth finder?
One use
is as an aid in navigation. If you have a chart, find a range, and know what the depth is, you can use the depth to help get a fix on where you are. Although that sounds more like David Burch lore than anything I would ever use.
True, bohemia, but any kayaker can…
use a Foretrex 101 GPS for that same info, and so much more. 
use of depth finder
I want to kayak my favorite rivers in SE - WI. to find the deep holes where all the fish are hiding. Another Question. If I bought a portable depth finder like the Cuda 168. Can I remove the transducer and mount it in my Canoe also? Some say they glue it to the hull of their Kayak. I want to use it in both boats.
Float
Mount the xducer on a float and use the cable to tow it. Put it in the water when you are ready to use it. Most portables come with a suction cup to temporarily attach the xducer to the boat. I like the float as you dont have as much drag.
What make of boat
if you have an Old Town that uses the three layer construction with the foam in the middle, it will not shoot through the hull. the transducer will have to be mounted outside.
make of Kayak
We have a kevlar Prospector, and a WS 145T plastic. I hope it will shoot thru both boats.
I have the Eagle Cuda 168
It has a suction mounted transducer which you suction cup to the hull. That way you can move it from boat to boat. the suction cup adheres very well, if fact sometimes it is hard to get it off.
depth sounder
Howdy
I have a hummingbird that works great the tranducer is mounted on the inside just aganist the hull in RTV. I use a 12volt emergency light battery that I can charge with my plug in the truck when traveling. Or at home in the trickle charger.
Works great and water proof.
I also have a GPS on board.
I hate to step out into deep water and sitting low to the water the GPS is great finding my way even after dark
ol Al
Wiring
Keep in mind if you mount your xducer in the hull you will have to have wires running inside the hull. The wiring will also have to be transfered to the other boat. If you still want to mount it inside the hull then here is another method. Use foam to build a dam or pool that fits snugly around the xducer in the location you want to mount the xducer. Partially fill it with KY jelly and make sure there are no air bubbles. Place the xducer into the jelly. This system makes it removable but messy. The 168 is cheap enough, $70 at Bass Pro that it might be easier to get one for each boat.
temporaty mount…
as pointed out in my earlier post, you can use plain water. No mess. Transmits the signal perfectly.