Dear Board,
I’m wondering if it is possible for your average Humminbird depthfinder to shoot through the hull of either of my canoes? I suppose I could actually try it myself but I am more interested in finding out if anyone has done it?
I own an Old Town Discovery Sport 13 made of Cross-Link3 and a Novacraft Prospector 17 made of SP3. Both are extremely heavy and the material is pretty much bulletproof. You’d quickly understand why I own those versions if you ever met me. 
So has anyone ever tried to do what I am asking about doing? If you did and it worked I’d like to hear how you did it.
Regards,
Goobs AKA Tim Murphy
I haven’t personally but …
– Last Updated: Nov-06-11 1:27 PM EST –
........ it will work . Others have had excellent success in thru haul shooting w/standard transducers .
Best performance is achieved when the haul being shot thru is solid w/o voids or air bubbles in the core . Also the mounting of the transducer must absolutely be a solid voidless connection and the transducer should be clean and smooth (wet sand face w/X-fine if nessasary) . The area you mount to on the haul should be completely smooth as well (smooth it as nessasary) .
Also you check the insulation on the tranducer cable . Repair or add extra jacket if damage or deterioration is seen . The sonar units are very sensitive to electromagnetic interference , and damage cable insulation or being bundled w/other electronic instruments cause static noise in the unit readout .
A silicon bed "is not" the prefered method for the connection mount because the silicon absorbs much of the energy transmitted by the transducer .
A solid (hard) epoxy bedding is the best prefered method . Know that you can sand the face of the transducer at will because it is a "thick" expoxy base material .
For waters up to say 50' depth , a low watt output and wide angle transducer are best . for deep waters like 100'-150' a higher watt output and narrow angle transducer are best .
Also you should smooth the area on the exterior of haul just beneth the transducer if it's scrathed up , etc.
Nothing stupid about the question ... people been doing it and wanting to know about it forever ... it works most of the time for most who do it with the understanding of the objectives in installation .
Thanks for the info
Dear pilot,
I thought I had read somewhere that epoxy was needed to mount the transducer. I can see how that would be a good idea in the bilge of a bass boat but maybe not for a canoe?
Given the need for epoxy, and the fact that my Old Town has a keel which creates a “hole” of about 1" in both depth and width right down the middle of the canoe I think I’ll stay with a portable transducer.
That “hole” makes an awfully big void that would have to be filled to perfection in order for a permanent mount to work.
In my mind there is too much margin of error and I’d probably wind up with a non-working transducer permanently mounted in an inconvenient place on the canoe.
Thanks for explaining the process though.
Regards,
Tim Murphy 
I see no reason why it has to …
– 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
depth sounder
Your Humminbird will work fine without doing anything fancy or permanent.
It will shoot right through fiberglass or aluminum. I’ve done it for years.
Using any type of tape, make a ridge (about the diameter) of a tuna can) somewhere on the inside hull of the vessel. Drip a little water from your paddle into the little pond, and set the transducer in the water. The transduver does not have to be submerged, you just need a little water between the face of the transducer and the hull.
This will reduce the sensitivity slightly. The unit may now only work well to 500’ depth, not the 600’ advertised.
I’ve even used mine when ice-fishing. Poor a little water from your water bottle on the smooth ice, then sit the transducer on the puddle.
Jerry
Very interested in the technique you’re describing, but can’t quite picture what you’re doing with the tape. Can you describe in a little more detail?
Thanks…Mike
Thanks for the tip
Dear Jerry,
I’ll definitely give your tip a try before I go to the trouble of gluing anything fast to the bottom of my canoe.
How do you think this would work? What if I took the plastic lid from a coffee can and cut the top of it out so that all that was left was the rim section that holds it to the can. If I duct taped it to the bottom of the canoe would that give me a good area to place the transducer?
I’d probably have to replace the tape from time to time to keep things relatively water tight but that wouldn’t take much work.
Regards,
Tim Murphy AKA Goobs
transducer
Keep it simple.
On a 2 week fishing trip with an aluminum canoe, we just took electrical tape and wadded it up into a crude circle and stuck it to the bottom of the canoe. A bead of caulk would do just as well. Drip some water off the paddle and put the transducer in the puddle.
I have owned fiberglass boats in which I just placed the transducer in the bilge water. Works fine unless the hull is balsa core of some honeycombed construction.
Just last week, I glued a 4" piece of PVC to the bottom of an aluminum row boat for a Humminbird transducer.
Be aware that the built in temperature sensor will only give the temperature of the bottom of the boat.
If the temperature is important to you, you can drill a large hole in the bottom of the boat, but then you may notice other drawbacks.
Transducer / coffee can lid
The ring from a coffee can lid should work fine. Forget the tape and just use a caulk of some sort (my favorite is “Amazing Goop”, found at most hardware stores.) The only reason we originally used tape is that while on the way to our fishing destination, we decided to stop an purchase the fish-finder. Tape is what we had with us.
As long as you don’t care about water temperature, shooting the signal right through the hull works fine.
Transducer / coffee can lid
The ring from a coffee can lid should work fine. Forget the tape and just use a caulk of some sort (my favorite is “Amazing Goop”, found at most hardware stores.) The only reason we originally used tape is that while on the way to our fishing destination, we decided to stop an purchase the fish-finder. Tape is what we had with us.
As long as you don’t care about water temperature, shooting the signal right through the hull works fine.