What are some suggestions on removing a Depth Sounder Thru Hull Transducer? Its been in for 20 years......... Help!!
Removing a Depth Sounder Thru Hull Transducer
- Thread starter Chuck711
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Chuck 711, Do you want a straight answer
or a smart A$$ answer? I can suggest a large hammer or an examination of the manner in which it was installed and an effort to reverse that proceedure. My boat came with TWO transducers. One was stuck to the inside of the hull inside of a plastic cup of some kind of oil that made a mess. The other was threaded about 2 inches in diameter and laying in a locker. The threaded one came with a large nut the probably was intended to secure the transducer to the hull after a hole was bored through the skin. I presume that loosening the nut would have allowed the removal of the transducer with some effort.
or a smart A$$ answer? I can suggest a large hammer or an examination of the manner in which it was installed and an effort to reverse that proceedure. My boat came with TWO transducers. One was stuck to the inside of the hull inside of a plastic cup of some kind of oil that made a mess. The other was threaded about 2 inches in diameter and laying in a locker. The threaded one came with a large nut the probably was intended to secure the transducer to the hull after a hole was bored through the skin. I presume that loosening the nut would have allowed the removal of the transducer with some effort.
Depth Sounder Removal
First, use a large aircraft pliers or wrench to remove any backing collar on the inside typically bolting the transducer to its backing / plywood hull reinforcing. Cut and peel away any sealant you can see from the inside and attempt to push and twist the unit back out of the hull. Assuming you don't succede, it's probably because of more sealant between the unit flange and the hull on the exterior, but you may be able to loosen it. Then from the outside use a piece of thin wire or strong fishing line and work it under the flange to 'saw' thru the sealant all around the flange. Go back inside and push and twist again. If the unit was sealed in with something like 5200, you may still not be successful. A last resort method then would be to grind away the outside flange of the unit from the outside with a Dremmel tool. (I assume you are removing and throwing the unit away because it no longer works anyway). Try to find a replacement unit that fits the same size hole and follow the manufacturer's installation directions. If the plywood backing is soft or deteriorated, remove and set a marine plywood replacement piece in epoxy; maybe even epoxy clear coat it for longevity. I'd probably use Life Seal as the sealant, which if I recall correctly, is the material recommended for below water use. Hope this helps, but fire back if something looks questionable to you.
First, use a large aircraft pliers or wrench to remove any backing collar on the inside typically bolting the transducer to its backing / plywood hull reinforcing. Cut and peel away any sealant you can see from the inside and attempt to push and twist the unit back out of the hull. Assuming you don't succede, it's probably because of more sealant between the unit flange and the hull on the exterior, but you may be able to loosen it. Then from the outside use a piece of thin wire or strong fishing line and work it under the flange to 'saw' thru the sealant all around the flange. Go back inside and push and twist again. If the unit was sealed in with something like 5200, you may still not be successful. A last resort method then would be to grind away the outside flange of the unit from the outside with a Dremmel tool. (I assume you are removing and throwing the unit away because it no longer works anyway). Try to find a replacement unit that fits the same size hole and follow the manufacturer's installation directions. If the plywood backing is soft or deteriorated, remove and set a marine plywood replacement piece in epoxy; maybe even epoxy clear coat it for longevity. I'd probably use Life Seal as the sealant, which if I recall correctly, is the material recommended for below water use. Hope this helps, but fire back if something looks questionable to you.
Removal necessary?
I faced the same question last year and decided not to remove the existing depth transducer. I looked at how well the old / non-working transducer was installed and since it was not leaking, I just cut the wire and left it in place. It also looked as though I would end up doing a substantial amount of damage in the process of removing the old transducer with no chance of getting a new unit to fit in the hole. So with that knowledge (or at least I thought I would make a heck of a mess at it) I decided to leave it in place. I then decided to silicone the new transducer in place inside the hull. I put a big glob of silicone on the inside of the hull, ensuring that there were no air bubbles in the glob, and then stuck the new transducer in it. Works great! The guys at Signet Marine said that I may lose some maximum depth sensitivity, but I don't really need to know when the bottom is over 200 ft down anyway. Good luck, Clayton Fawcett s/v Walkabout Hunter 26.5
I faced the same question last year and decided not to remove the existing depth transducer. I looked at how well the old / non-working transducer was installed and since it was not leaking, I just cut the wire and left it in place. It also looked as though I would end up doing a substantial amount of damage in the process of removing the old transducer with no chance of getting a new unit to fit in the hole. So with that knowledge (or at least I thought I would make a heck of a mess at it) I decided to leave it in place. I then decided to silicone the new transducer in place inside the hull. I put a big glob of silicone on the inside of the hull, ensuring that there were no air bubbles in the glob, and then stuck the new transducer in it. Works great! The guys at Signet Marine said that I may lose some maximum depth sensitivity, but I don't really need to know when the bottom is over 200 ft down anyway. Good luck, Clayton Fawcett s/v Walkabout Hunter 26.5
Plastic or bronze?
I took a plastic one out a couple of years ago that had been in for 15 yrs... Tried all sorts of stuff, finally ended up with a 1/4" chisel and a hammer. It worked great. B
I took a plastic one out a couple of years ago that had been in for 15 yrs... Tried all sorts of stuff, finally ended up with a 1/4" chisel and a hammer. It worked great. B
Did it last summer!
I replaced both speed and depth TD's last spring. They had been in since 1988. I had to chip away the round, plywood backer-boarding/spacer (tedious, but not too difficult) and had to use things such as a screwdriver or chisel w/hammer. This gave me a half inch to play with. Since I couldn't remove the large nuts, I was able to push the mushroom head of the TD out about 1/2". Then, from the outside of the boat, I took a SAWS-ALL and lopped off the mushroom heads parallel to the hull. They were bronze TD's and required a metal-cutting blade to do the cutting. It did no significant damage to the hull. I thought about leaving them (the TD's) in place, but this was quickly dispelled when I was told that at resell time, a surveyor would definitely put his finding in his report and would indicate a sloppy owner. So I removed them. Keep in mind that you can use the same holes unless the TD's are a different diameter. That was my problem. If the holes are larger than the new TD's, then you will have to glass the holes and redrill new holes - an expense I didn't figure on. Also. The new wires have a large head on them that attaches to the back of the gauge. This eliminates a transformer. If you try to use the same wire runs, the new connectors may not fit through the holes that are already drilled (or occupied by other wires). Be sure to do your homework.
I replaced both speed and depth TD's last spring. They had been in since 1988. I had to chip away the round, plywood backer-boarding/spacer (tedious, but not too difficult) and had to use things such as a screwdriver or chisel w/hammer. This gave me a half inch to play with. Since I couldn't remove the large nuts, I was able to push the mushroom head of the TD out about 1/2". Then, from the outside of the boat, I took a SAWS-ALL and lopped off the mushroom heads parallel to the hull. They were bronze TD's and required a metal-cutting blade to do the cutting. It did no significant damage to the hull. I thought about leaving them (the TD's) in place, but this was quickly dispelled when I was told that at resell time, a surveyor would definitely put his finding in his report and would indicate a sloppy owner. So I removed them. Keep in mind that you can use the same holes unless the TD's are a different diameter. That was my problem. If the holes are larger than the new TD's, then you will have to glass the holes and redrill new holes - an expense I didn't figure on. Also. The new wires have a large head on them that attaches to the back of the gauge. This eliminates a transformer. If you try to use the same wire runs, the new connectors may not fit through the holes that are already drilled (or occupied by other wires). Be sure to do your homework.
Use a sharpened putty knife
My brother works in a boat building plant and they have to occasionally take out a thru hull here and there. I had him replace my spedo transducer. First he backed off the nut on the inside of the thru hull. Then he took a wide putty knife and sharpened the blade and tapped it behind the outside edge of the thru hull to "cut" through the 5200 (or what ever adhesive they use). The thin blade cut through the adhesive easily. Then he just tapped out the thru hull out from inside. It was clean and easy and no damage to surface of the hull.
My brother works in a boat building plant and they have to occasionally take out a thru hull here and there. I had him replace my spedo transducer. First he backed off the nut on the inside of the thru hull. Then he took a wide putty knife and sharpened the blade and tapped it behind the outside edge of the thru hull to "cut" through the 5200 (or what ever adhesive they use). The thin blade cut through the adhesive easily. Then he just tapped out the thru hull out from inside. It was clean and easy and no damage to surface of the hull.
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