Uncooperative Through Hull

Dec 19, 2006
5,809
Hunter 36 Punta Gorda
I changed some thru hulls a few years back and used a tool inserted into the opening
from the outside and as big a pipe wrench on inside but one just wasn’t coming off.
I got out my sawzal and pushed down on the blade to cut it off but mine were not bolted to the hull.
And all new backing plates marine plywood with expozy
Nick
 

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Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
Dave,

Two words....

Pipe wrenches

Quality pipe wrenches such as Rigid, not junk that slips. I have yet to find a single NPT to NPT tail piece I could not extract from a seacock using the correct tools for the job. On the valve end use a smooth jaw pipe wrench and on the tail-piece a toothed wrench... A piece of 1 1/4" or 1 1/2" black pipe can be slid over the end of the pipe wrenches for more leverage.

My "cheater bar" has seen some serious abuse but it now fits my Rigid pipe wrench's like a glove...:wink:
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
RC,

Removing the tailpiece was easy, it's sitting on my workbench.

The valve is a Groco Flanged Ball valve. The difficulty is separating it from the through hull fitting. The current installation instructions from Groco call for sealant between the through hull fitting and the valve which will also glue it to the backing plate. It is impossible to get enough access to the base to wedge the flange up or use Debond to break the bond, or get an oscillating tool scraper between. The valve sits in a small cabinet on a curved section of the hull. If you are familiar with the Sabre 362 it is the head intake which is in a cabinet below the drawers at the Nav station.
 
Nov 26, 2008
1,966
Endeavour 42 Cruisin
I had a similar issue with trying to remove a bad ball valve. Limited space to put muscle on it. It was MUCH easier and quicker to cut off the mushroom thru hull and toss the whole thing. I used a grinder to cut notches in the end of the mushroom and it broke off with a bit of persuasion, took maybe 10 minutes or less. Now, all new stuff from end to end and no need to worry for many years.
 
May 7, 2012
1,338
Hunter e33 Maple Bay, BC
The difficulty is separating it from the through hull fitting.
If removing is this difficult will replacing it be as or more difficult? Will you be able to get enough purchase on the replacement to ensure it is water tight?
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
If removing is this difficult will replacing it be as or more difficult? Will you be able to get enough purchase on the replacement to ensure it is water tight?
There is enough access to reinstall it. I think the big issue is the adhesive caulking that was used to seal it on the inside of the hull. Basically it glued the valve to the mounting plate as well as glueing it to the through hull. I think (hope) that @BigEasy suggestion to grind off the mushroom end will free up the fitting enough that I can break the valve free from the mounting plate. I'll know better tomorrow.
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
You can carefully heat the head of the thru-hull fitting then machine (bench grinder nothing fancy) some 1/4" steel bar stock to fit the dogs in the thru-hull quite snugly. Heat the through hull with a heat gun and then use a pipe wrench on the thru-hull fitting to see it you can un-thread it. The seal for this should be between the mushroom head and hull as well as threads but heat will soften the bond. If this method does not work, and it does not always work, time to physically uncover the bolt heads and remove it and replace it.. You can grind off the head of the thru-hull in order to save the seacock or just call it a day and replace the whole kit and kaboodle.
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
You have a much greater chance of breaking the bond on the thru Hull flange than on the threads and will end up with the whole assembly spinning. Cut the flange off pull out the valve and get it on a bench if you want to investigate further.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
Success! The valve and through hull are no longer on the boat.

Began with the least destructive method first. Created the tool suggested by @Maine Sail, heated the through hull with a high temp heat gun, stuck the tool in the through and bent the tool. Went to Plan B.

Got the angle grinder out and started grinding the mushroom off. Then the battery died. Then the second battery died. While waiting for the batteries to charge, tried unscrewing the valve, and, ::drum roll:: it easily unscrewed. I think the heat from grinding softened the caulk making it possible to unscrew the valve.

Finished grinding off the mushroom and used the now bent tool to unscrew the remains of the through hull from the hull.

Thank you to all who offered suggestions!

Before:
IMG_1655.jpg


After:

IMG_1659.jpg
 
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Likes: Ward H
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
Can you tell if there is any deterioration of the female threads in the top nut of the Groco valve? I assume that is where the original leak came from, because there was no leak when the valve was closed. The top nut is replaceable as you can see in this Groco pdf. https://www.groco.net/media/file/file/b/v/bv-series.pdf.
I have to get a magnifying glass to see the threads more clearly. On the current models it appears that the top nut can be removed. Mine is a 1993 model, it looks to be press fit and slightly off center. I'll get a better look at it tomorrow.