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Removing Thruhull transducer in water

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luckystar
Navigator

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USA
236 Posts

Initially Posted - 08/22/2002 : 15:57:16

Is it possible to remove a thruhull transducer (for my depth sounder) and replace it with a new one (same manufacturer, same size) while the boat is still in the water? Could someone with tanks go under and cover with something long enough to get the new one in? Just curious if it's possible. I'm pulling out first of next year (in the south) for a bottom job but the lake is low right now and I need my sounder to work. Any ideas? I don't want to rent a trailer twice! thanks!

Patrick Burnett, Little Rock, AR
S/V Lucky Star #2707 1982 SK/SR

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3321 Posts

Response Posted - 08/22/2002 : 17:47:51

Patrick - I changed out mine a few years back and only got about a quart of water in the boat. All you need is to be prepared:-
1. Place new transducer alongside old one.
2. Unscrew old one, whip it out and immediately place palm of other hand firmly over hole.
3. Pick up new transducer and orient it correctly.
4. Pull hand off hole and pop in the new instrument.
5. Mop up water.
If you feel you need more time, then push a soft pine plug into the hole during #2, but you will get more water in the boat than when using your palm.
Derek

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 08/22/2002 : 20:45:37

I agree you can pull the old unit and only get a small amount of water in. I removed my paddle wheel and instaled a plug.

Doug&Ruth
Wind Lass
Tacoma Wa.

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Buzz Maring
Master Marine Consultant

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USA
1768 Posts

Response Posted - 08/22/2002 : 20:55:05

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
I removed my paddle wheel and instaled a plug.

Doug&Ruth
Wind Lass
Tacoma Wa.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Hi Doug,

I want to do the same thing ... where did you get a plug?

Thanks!

Buzz Maring, C-25 SK/SR #68, "Freya"

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tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 08/23/2002 : 09:26:20

Hi all,

The guy did say depth sounder didn't he? Thought so. The advice given will work for the paddle wheel...not so for the depth transducer. This unit must be fitted from the outside..with caulking and then tightened from within. Can't see any reasonable inwater fix for this short of tying your bow to the dock at high water and be ready to do the installation at low water. Though it's probably doable this way it would help to have the congregation on bended knee on your behalf to pull it off.

Val on "CALISTA" #3936

Val Bisagni

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luckystar
Navigator

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USA
236 Posts

Response Posted - 08/23/2002 : 13:02:12

Sheesh, it sounded pretty good for a second there, but now...
How would I know if mine is set up that way? I have the kind that screws in from the inside. I have the plug that came with it, apparently and it looks as though it simply slides in from the inside and has a black rubber gasket. I went diving on the transducer and it is flush with the hull. Where and why would it need caulk? I could understand if it was a knot meter that had the exterior assembly that I couldn't do it... still, tough to decide!

Thanks for the advice guys! I love this list!

Patrick Burnett, Little Rock, AR
S/V Lucky Star #2707 1982 SK/SR

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tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 08/23/2002 : 17:14:58

Patrick,

The plug goes with the speedo (paddlewheel)transducer. That can be accessed from within. The depth sounder transducer can only be replaced from without. The boat must be high and dry until you can remove the ring nut inside the hull, then pop the transducer out (easier said than done(remember Murphy)next clean the hull area where the the transducer goes...plaster the new transducer with polysulphide caulk and insert it (all twenty plus feet of cable with it)then from within place the ring nut over the unit and partially secure it giving the caulk time to set-up then finish tightening it. That's going to be a little tight on time with the bow hanging from the dock. When I did mine I let the caulk set overnight then firmed up the nut. In truth I'd not consider doing this maneuver anywhere but on the hard.

Sorry if it don't fly for you but that's my take on the proceedings.

Val on "CALISTA"# 3936

Val Bisagni

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luckystar
Navigator

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USA
236 Posts

Response Posted - 08/23/2002 : 18:05:49

Thanks, I think I've arranged a solution, and a safer one at that! I found a trailer that I can use for two days in about a week or so when someone launches their boat and before they take the trailer back to storage (people are real wierd about trailer rentals down here for us sailors!) That will give me time to haul (don't have to de-rig) powerwash bottom, new keel cable, a little keel grinding until the BIG HAULOUT (ugh!) and install the new transducer. So while I'm at this, I'm thinking of replacing the unit with an autohelm unit that will match my autopilot nicely (not installed) Or just another reason to spend more boat units!

Patrick Burnett, Little Rock, AR
S/V Lucky Star #2707 1982 SK/SR

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OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 08/26/2002 : 02:20:36

Apparently (or even obviously) not all instrument thru hulls are alike. I updated my speed and depth units (SR Mariner) this summer and replaced both from within without any sealants.
Funny how POs will whip out the silicone to stop leaky instrument thru hulls instead of just calling the manufacturer for new o-rings!

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luckystar
Navigator

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USA
236 Posts

Response Posted - 08/28/2002 : 22:51:11

The fella at SR Mariner had a pretty good idea for removing and replacing their brand of transducer: He said, get a sponge and stuff into the hole after you remove the transducer (it comes out from inside with no install on the outside of the hull like some units). This will give you time to check everything and the o-ring, etc. Then when you want to put the new one in, just slide it in and push the sponge out thru the hull. He said the sponge will float up after a few minutes or someone can be swimming next to the hull to get it on the way out. I thought this was smart!!

Patrick Burnett, Little Rock, AR
S/V Lucky Star #2707 1982 SK/SR

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eric.werkowitz
Captain

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USA
283 Posts

Response Posted - 08/29/2002 : 17:42:56

As I recall someone posted some time back that he knew some divers that were installing thru hulls in the water. One guy worked in the boat, one under the boat. The guy inside drilled the hole through the hull with a >>battery powered<< drill and hole saw. When the pilot bit on the hole saw broke through the hull the guy under put a plunger (plumber's helper) over the hole. When the hole saw bit the rest of the way through, the lower pressure inside the boat securely sealed the plunger against the hull. I don't remember the details about sealing a new hole under water, but it seems that the idea would work very well for changing out a transducer if its cool to put someone in the water. I doubt that scuba would be needed, just a mask.

Eric Werkowitz
C25 #4969

Edited by - eric.werkowitz on 08/29/2002 17:46:28

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Buzz Maring
Master Marine Consultant

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USA
1768 Posts

Response Posted - 08/29/2002 : 18:06:18

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
As I recall someone posted some time back that he knew some divers that were installing thru hulls in the water. One guy worked in the boat, one under the boat. The guy inside drilled the hole through the hull with a >>battery powered<< drill and hole saw. When the pilot bit on the hole saw broke through the hull the guy under put a plunger (plumber's helper) over the hole. When the hole saw bit the rest of the way through, the lower pressure inside the boat securely sealed the plunger against the hull.

Eric Werkowitz
C25 #4969
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

American ingenuity ... there's nothing like it. <img src=icon_smile_cool.gif border=0 align=middle>

Buzz Maring, C-25 SK/SR #68, "Freya"

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