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Old 05-08-2021, 11:31 AM   #1
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Nick F's Avatar
City: Vancouver
Vessel Name: L'Attitude (previously Khenko)
Vessel Model: CHB 34 1976
Join Date: Sep 2020
Posts: 77
Changing thru-hull valve in the water

Here is a method I just used that might be of interest (photos are in order of sequence):

I wanted to replace a poor quality 1-1/4" valve in the head with a proper bronze valve. The valve is on the hull bottom, a few inches below the water line and I looked for a safe way to do this without pulling the boat out of the water.

At first I looked at an inflatable packer (Cherne 270008 Rubber Test Ball Plug, 3/4"-1-1/4" on Amazon), then I thought about trying to make a mechanical expanding packer, then I discovered that you can buy these inexpensively - they are sold for testing plumbing. (C$17 - Cherne 269883 Kwik 'n Sure 1-1/4-Inch Plug on Amazon)

The test plug that I bought had a big wing nut on it and needed some modification to be able to insert it through the valve. I added threaded rod and a piece of metal tube (from my scraps box) and assembled the "packer" device shown in the photo.

I added a short piece of ABS pipe to the top of the old hull valve, such that the top of the ABS was above the water line. I then opened the valve and could see daylight through it and I cleaned the bore of the thru-hull skin fitting with a mini wire brush taped to a stick.

I then inserted my packer and tightened the wing nut to expand the rubber bung. I then unscrewed the old valve and slid it off the packer extension. I gave the extension of the packer a good "wiggle" to see how firm it was and found it was very solidly held. I cleaned the threads on the skin fitting, applied Teflon tape and installed the new valve.

Next I installed the ABS pipe again, loosened the wing nut, pulled out the packer and closed the new valve.

Before doing this in-the-water changeout I was somewhat nervous, but the operation went very smoothly and I would not hesitate to do it again. The longest part of the whole operation was cleaning the threads of the skin fitting prior to installing the new valve. I think that the inflatable packer would also work. It is a bit more expensive ($57) and you need a pump (bicycle pump?), but it would not need modification.

Attached Thumbnails
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IMG_3953 (2).jpg   IMG_3954 (2).jpg   IMG_3957 (2).jpg   IMG_3958 (2).jpg   IMG_3959 (2).jpg  


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Old 05-08-2021, 12:29 PM   #2
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RickyD's Avatar
City: Long Beach, CA
Vessel Name: Aquarius
Vessel Model: Californian 55 CPMY
Join Date: May 2018
Posts: 311
Wow, what a smart method. I just did one by paying my diver to plug the hole from underwater while I spun off the old valve and installed a new one. I have two more to do. I have an unused and capped off valve way forward that is easy to get to. I believe it used to supply water to the nearby anchor wash down pump. I'm assuming that the PO had it fail and capped it off, then ran the hose to another valve that is really hard to get to. That valve is now clogged or has failed partially and when I haul the boat I'll replace both valves and re-run the supply hose to the valve I can get to best. Unfortunately your method will not work for my clogged valve as it is so hard to get to. Its time to do bottom paint so it won't be long, but I'll remember your method. Very smart.

Aquarius 1991 Californian 55 CPMY Long Beach CA
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Old 05-09-2021, 05:47 AM   #3
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City: Seneca Lake NY
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 5,146
They make & sell a tool for that but I like the creativity and savings of DIY.
2008 MS 34 HT Trawler
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Old 05-09-2021, 06:55 AM   #4
City: Pompano Beach
Join Date: Jun 2014
Posts: 23
thru-hull replacement

try this...
1-1/4 dowel approx 8-10" long
1-2" disc of hypalong or heavy vinyl
1-small screw and small flat washer

Punch a hole in the middle of the 2" disc.
Push the screw with the washer thru the disc and screw into end of the dowel.
Push the disc thru the valve until it is below the hull and then pull up flush to bottom of hull.
Remove valve .

Taa Taa!!!

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Old 05-09-2021, 07:13 AM   #5
City: Great Lakes
Vessel Model: OA 440
Join Date: Aug 2017
Posts: 712
Very clever ideas. Unfortunately, I have a seriously stuck valve in the closed position, so can't run a rod through the valve. But fortunately, the valve is located near to the edge of the hull, so was able to insert an expandable rubber engine freeze plug ($2.89) from the outside while hanging over the side of the dinghy. Had to modify it by creating two grooves to clear the "ribs" inside the lower portion of the thru-hull. It appears to have sealed OK when I tightened the nut....I'll find out when I unscrew the valve...
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Old 05-09-2021, 10:18 AM   #6
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Join Date: Jun 2008
Posts: 4,252
Nick, nicely done!
Jay Leonard

New Port Richey,Fl
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Old 05-09-2021, 10:21 AM   #7
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City: 'Merica
Join Date: Apr 2021
Posts: 3
Wow very impressed. Well done

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