Kayak Thru Hull Transducer

[peguinpower]

After hearing so many reports of better fish finder performance by hanging transducers over the side of the kayak, I decided to try it for myself. Try I did but with a more "factory: approach

First of all, some research. Here is what Lowrance has to say about thru the hull installs with purpose built Txs.

"Your unit may read erratic depth with a Shoot-Thru Hull Transducer if the transducer is not intact or if you are using the wrong kind of epoxy. The main reason why you are getting erratic depth with your Shoot-Thru Hull transducer can be traced back to the way the transducer is installed.

Shoot-thru-hull transducers are epoxied directly to the inside of fiberglass boat hulls. The sound is transmitted and received through the hull of the boat - but at the cost of some loss of sonar performance. (You won't be able to "see" as deep with a shoot-thru-hull transducer as one that's mounted on the transom.) The hull has to be made of solid fiberglass. Don't attempt to shoot through aluminum, wood, or steel hulls. Sound can't pass through air (rotomolded kayaks can have air bubbles in the hull), so if there's any wood, metal, or foam reinforcement, it must be removed from the inside of the hull before installing the transducer. Another disadvantage of the shoot-thru-hull transducer is it can't be adjusted for the best fish arches. Although there are disadvantages to a shoot-thru-hull transducer, the advantages are considerable. One, it can't be knocked off by a stump or rock since it's protected inside the hull. Two, since there is nothing protruding into the water flow, it generally works quite well at high speed if it is mounted where a clean laminar flow of water passes over the hull. Three, it can't be fouled by marine growth."

So I pulled out my my old tx. Despite working very well, I guess it was not a perfect installation.




Here is the new unit I'll be putting in.



Onto the installation....

pilot hole



firing up the Ryobi



builder's remorse



hole



clean up. also used acetone. 5200 doesnt like alcohol



test fit



secured with tape before working on the inside



bolting the inside down



before cleaning up the 5200



completion......sea trials on saturday



this project is not for everyone. my kayak is out of warranty. you may or may not have the skills to work stuff like this, find a professional marine installer. you may or may not want a better FF picture, all the best to you. if you are afraid to work below the water line, that's your issue. I always carry a hand action bilge pump. dont be hatin

thanks to our LA County locals for doing it first. Humminbird also helped a lot by providing tech help and advice over the phone.

[Holy Mackerel]

Nice job, where did you get this unit from?



FWIW, I shoot thru Hull on my kayak, and have my puck directly in water on my boat, and haven't noticed a trememdous difference in the reading. I use the same FF/GPS on both kayak and boat, each have their own puck. I wish more kayak manufacturer's would just build an independent puck area on the bottom of the kayak in the mold, and not be a part of the kayaks scupper system.

chris

[peguinpower]

This is a Humminbird Flush Mount Transducer part no. XFM-9-20-P

I got it from Amazon.com

You'll need another part #TG-W to get temps (no hole needed)

The height is 4 to 4.5 inches (approx). The hole is 2 inch round. It it seems to be the standard hole in the FF industry for low power (sub 1000 watt) TXs.

Garmin and Lowrance makes theirs, with Lowrance being the most expensive.

[buki]

penguinpower,

do you get a better picture and depth reading with the new install?

i have an eagle cuda that stops working when i'm at depths greater than 125' and i suspect it's the transducer install that is causing this.

thanks in advance.

[peguinpower]

Originally Posted by buki

penguinpower,

do you get a better picture and depth reading with the new install?

i have an eagle cuda that stops working when i'm at depths greater than 125' and i suspect it's the transducer install that is causing this.

thanks in advance.

I'll let you know after this weekend when I do sea trials. my old gooped install saw all the way to 800 feet. the reason I am doing this is the get better pics on the screen. how useful that is, is a personal preference.

I am not the first to do this. Jim Day did his first and a few other guys confirmed that the OK scupper mounted fish finders perform much better than internal installs.

regarding if my tx fit in this tx. its a whole new transducer I had to buy. if you have a new Humminbird FF, send the OG transducer to the company and they will exchange it for free.

again, I do not recommend that anybody else does this. its all up to your skills and if you want a better performing FF.

[buki]

Originally Posted by peguinpower

I'll let you know after this weekend when I do sea trials. my old gooped install saw all the way to 800 feet. the reason I am doing this is the get better pics on the screen. how useful that is, is a personal preference.

I am not the first to do this. Jim Day did his first and a few other guys confirmed that the OK scupper mounted fish finders perform much better than internal installs.

regarding if my tx fit in this tx. its a whole new transducer I had to buy. if you have a new Humminbird FF, send the OG transducer to the company and they will exchange it for free.

again, I do not recommend that anybody else does this. its all up to your skills and if you want a better performing FF.

I saw Jim Day's post and it got me interested. After seeing yours, I'm seriously thinking about doing this. Your install is much simpler and looks like something I can do. I already have a kayatank and this isn't a big change for me.

Thanks for the info on the Humminbird. I was going to ask about that. I cracked the LCD on my Eagle Cuda a few weeks ago and I may have to swap it out for a Humminbird.

Thanks.

[dorf]

Looking at your install I have a couple of questions.
1. Is that caulk inbetween the transducer and the bottom of the hull?
2. Is that a rubber gascic on the inside? If so wouldn't it be better served on the outside?
Transducer.JPG

I do not mean to come accross as critical to you installation. I have no experiance what so ever. Just wondering. I think that your install is very nice and maybe, one day, I will venture to make a simular modification.

Thanks for your post.

Paul.

[j mo]

Solid post-

Did you replace your transducer all together or did it fit inside the unit?

has anyone done this for the eagle cuda series?

[peguinpower]

Just finished the install today. First sunny day in socal in about a week.

FF now has 3 wires coming out. The power, tx and temp sensor.


Temp sensor was zip tied to the sail mast and glue with silicone to the hull bottom. It appears to respond well to ambient temps. The hull should be pretty responsive to ambient water temps. I did a test with a temp gun, there is a 1 degree differential between the FF readout and outside temp of the hull. Adjusted for offset in the FF menu. Spot on now



Last look at the tx, sea trials tomorrow. Gonna bring a pump

[Brian Sanner]

Being that it is still relatively early on the 16th, I hope the sea trial went well. Interrested to hear it any water made it in at all. I had a small pinhole in my old kayak that through the course of the day would suck in gallons of water. Kayaks compress and decompress hundreds of times a day depending on conditions and what not and when they decompress, water gets sucked in......................at least that is what I was told from the manufacturer a couple of years ago. Anyhow that is still one good looking install and hope for the best. I also would like to see more manufacturers make some kind of allowance for transducer mountings and come up with something clever for bringing wiring through the boat * I have one but really do not like the cable clams very much , I do understand that the molds are very expensive and manufacturers are doing their best to think of the needs of the angler. Very good and informational post.

[peguinpower]

Test results:

The original gooped transom mount tx vs. the thru-hull tx, the thru-hull has about 100% better performance. The thru-hull tx versus my other kayak, with a purpose built shoot-thru-hull tx is better by about 30%.

That said, I would say that I may settle for a purpose built shoot-thru-hull installation with epoxy next time. Its a small sacrifice compared to drilling thru the hull Smile

I observed that I get arches on the screen as against having almost none before. I can track a 3/8 oz lead headed swimbait 100% of the time now. Previously, I could only see the heavier metal lures, and even those, intermittently. It was also interesting to see weaker signals, the most interesting of which was seeing an arch over the bottom reading. Halibut? Duhno. Nothing was biting today.

Secondly, the seal. I am not entirely sure if I have a leak. I used the 3M 5200 very sparingly. After 5 hours on the water, I drained the hull and came away with less than 1/4 cup water. On the water, I had a small puddle that you can slap with your hand, but that was all. Nothing a shamwow couldnt handle Smile Not enough to get a hand pump primed.

I am not sure if this was from the transducer or from constantly opening the center hatch to check for leaks. As any Hobie owner knows, opening the center hatch makes water on the hatch drip into the hull.

I will be doing more tests to check if I do have a leak.

Conclusion: I should do a static test in a pool or something, but sadly, I don't have that kind of time right now (the first sea trial lasted 5 hours).

If there is any conclusion to be had at this point, GOOPED transducers are short changing the user. There is more performance to be had with alternative installations.

Do I recommend a thru-the-hull TX installation. If I get a bone dry seal, I would say yes, but that remains to be seen.

[Iceman]

Bing, looking at the install, I'd be surprised if even one drop came through.

[yakrider]

I sure wish Lowrance would make one of those

[Jason]

Bing, thanks for the motivational post.



FWIW, the hull is almost 1/4" thick where I drilled the hole.

After a solid year of use, this area of the hull has almost no scratches.

Sea trial on Sunday.

[peguinpower]

Originally Posted by Jason

Sea trial on Sunday.

I would really be interested in your review. Good luck!

/bing

[ronbo613]

First of all; I would say it takes some good sized balls to drill a big hole in a perfectly good boat.

If there is any conclusion to be had at this point, GOOPED transducers are short changing the user. There is more performance to be had with alternative installations.

I don't know if that's true. I have a transducer in my kayak that shoots through the hull that saw to 3K'(that's as far out as I've ever gone in the ocean); no problems, perfect imaging on a cheap Eagle fishfinder. I also had a much more expensive finder on a 23' Skipjack with an external transducer.
The external transducer was not much more accurate than the one in my kayak; readings were affected by bubbles in the water. Looking at the photos of the transducers removed from the kayak hulls in this thread; there is no doubt the bubbles in the Goop; or whatever it is that was used to mount the transducer to the hull; affected your readings. The key is to apply the Goop; or whatever, slowly and bubble-free; then push the transducer down slowly so no bubbles are created. The end result should be a "thin as skin" layer of Goop between the transducer and the hull. Any air bubbles in the Goop should appear on the perimeter of the transducer as the bubbles are forced out from under the transducer body.
But hey; if an external mount works better; that's great. If you fish in a more remote area; where your kayak is dragged across rocks and logs and non-urban launch sites; anything sticking out of your kayak is not going to fare well.
Depends on what you do.