Through hull FF?

Hey all. I'm trying to decide on a FF. And I am planning on using the transducer through the hull. I had been looking at the Hook 4 as my first option and the raymarine dragonfly 4 as my second option.
I know some people suggest using epoxy to fix the transducer. But I wanted to know if anyone had other options that are less permanent?
I saw one guy fixed it in his hatch and filled it with water, anyone able to comment on this method?

Get a foam gardening pad, cut it to fit the transducer snug.  Glue it down with "marine goop".  Fill with water, shove transducer in.  You might not get optimum results with the downvision / downscan, but it will work. 

Get a foam gardening pad, cut it to fit the transducer snug.  Glue it down with "marine goop".  Fill with water, shove transducer in.  You might not get optimum results with the downvision / downscan, but it will work.

Does the marine goop come off easily or is it pretty much permanent?

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Yes, GOOP comes off if you want to take it off, but if you don't want to remove it, it will hold whatever in place indefinitely.

The topic of mounting a thru-hull transducer is covered extensively in several threads.  SEARCH is your friend.

What you can't do is allow air to get between the transducer and the hull or you'll get wild signals back to the head unit.  That is why many use the foam-puck-water-bath method Lee is referring to.  There are other methods, but this is the quickest and it's very reliable.

Awesome thanks. I found the other threads. Most people were talking about trying to keep it permanent. My yak is also a ww and touring yak so I just wanna make sure I can remove it.
Thanks guys

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I used the duct seal method shown in this video. It worked well for my sonar/downscan unit. Just top the reservoir with water when you launch, it only needs 1/4 of water in the bottom. The edges in the photo are a bit collapsed as I had moved the transducer to another kayak. All that needs to be don to re install is mould the edges of the duct seal up and pinch some of the edge of the seal over the edge of the transducer to hold it in place. Note that side scan will not work in hull.
I have some photos of my installation but don't have time to size them down right now.

I use the method Lee mentioned with my Elite4 chirp and a piece of pink foam.  I leave the transducer in my hull all the time (fill it with water each trip).  If I decide to just go paddling or don't need the fish finder, I can still take the transducer for a ride and just don't mount the FF body.  My transducer wires were installed using a thru-hull wiring kit (hobie) and the wire connectors stick out from the side of one of my mesh pockets when not in use. 

Awesome thanks. I found the other threads. Most people were talking about trying to keep it permanent. My yak is also a ww and touring yak so I just wanna make sure I can remove it.
Thanks guys

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If you want removable, the foam receptacle is your best bet. You'll want to use sandpaper to rough up the inside of the hull, but even then the marine goop will come off if you want it off. HDPE (kayak plastic) is extremely slippery at the molecular level.


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I use the duct seal method.  I usually replace it every year because it gets messed up with duck hunting (shoving deeks up in the hull tips and all the sand and mud)  I have found it to be really reliable.  On occasion if the well gets messed up you might have to add water to it etc.  That can sometimes be annoying, but the simplicity of it makes really useful if you use your kayak for multiple purposes.

Good luck.

FINE sandpaper.  You just need to take the shine off the surface.

Shoot thru the hull, shoot me in .......

Have you looked into putting the transducer on ram mount and hanging it over the edge. I've seen a few guys run that setup mostly with sidescan but it would allow you to remove the entire FF very easily.


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Just finished a redo on my FF through the hull installation. Originally used the foam cut to the transducer size and GOOP to secure to the hull.  Found the water loss and splash to be a hassle.  So I took a Rubbermaid 4 cup container.  Removed the bottom of the container.  Ran a small bolt through the container to support the Garmin 500C transducer.  GOOPed to the kayak hull and Duct Seal to complete the waterproofing.  Filled with water and tested it yesterday. Worked great. Best imaging I have gotten, including the Foam puck method.  Seems that the water surrounding the transducer help reduce/eliminate the noise from surface junk.  The Garmin 500C is a great FF.

Mentioned it in an earlier thread, but I use the magnetic through hull.  I cut a breadboard piece, roughed up the inside, and prepared to glue it.  Before doing so I aluminum riveted velcro straps to hold the magnet inside. I put plastic wrap in the hole in the breadboard and used the magnet on the outside to hold the inside one in place for a couple of days.  Made sure I had the outside magnet set up with the transducer so I had a good downward shot.  I didn't like the brackets (noise, collecting seaweed, etc) so bent some galvanized strap steel to fix to the outside magnet and transducer.  I leave it in the kayak to start and reach out with outside magnet and it snaps into place.  Hasn't failed for a couple of years and the galvanized strap steel holding the transducer makes no noise while moving.  Simply lift it up and off when coming to shore. 
The pic shows the inside where the magnet is held in place with the velcro riveted to the breadboard.  No one sees it