Replacing the thru-hull and seacock for the marine toilet - Beneteau Oceanis 40 2008

M

miraculix

.
Jun 24, 2019
42
Beneteau Oceanis 40 Havre de Grace
Hi all,

I am struggling to replace the thru-hull and seacock for the marine toilet. Not only is the space pretty tight, a replacement using parts from Groco cannot be installed because there is not enough space. The elbow cannot be screwed into the valve. :banghead: I called Groco to see what they would suggest, and they recommended a flanged valve. I told them this might be difficult because of the location and sent them some pictures. With the pictures, they recommended this.
unnamed.jpg


That will certainly fit, but I do not feel comfortable with this. I am sure it's doable, but two screw connections before the seacock, not sure if I like that. I guess in the end I will go with a flanged valve. I will have to fill the recess around the hole, using a small disc from G10 and glue this into the recess, redrill the hole, and level the backing plate with thickened epoxy, which will be necessary because of the stupid rim in this area.
Any other thoughts?
Thanks Christoph

IMG_5324.JPG


 
Ralph Johnstone

Ralph Johnstone

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Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
Looks like a bit of a sticky wicket.

If you are stuck with two screwed joints, in order to avoid getting screwed yourself, be SURE to use an additional paste sealant with the teflon tape. Something like :

1747930916984.jpeg


Teflon tape by itself on cold fittings is not good, teflon tape and paste sealant is almost 100% guaranteed.
 

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BigEasy

BigEasy

.
Jun 21, 2004
2,888
Beneteau 343 Slidell, LA
Why not replace it with the same factory configuration, using Groco thru hull fitting, ball valve, & tailpiece?
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
BigEasy said:
Why not replace it with the same factory configuration, using Groco thru hull fitting, ball valve, & tailpiece?
Click to expand
Purists don't plug the NPS threads of the thru-hull into a ball valve with NPT threads.

I know, I know, I know it's not kosher. All boat mfg's do it that way.

That's the way it is unless you want to have thru-hulls with extra thick walls about 12" long in all cases. You buy them, cut to length, and then apply an NPT hand threader die to cut a male NPT thread on the end. You'll need a gripper thing-a-majig to hold the mushroom while you thread the NPS pipe.

A brilliant idea. Now to find someone stupid enough to buy the :

- special thru-hull
- hand threader
- correct size dies
- do-dad to hold the mushroom
- bandages
- gauze
- anesthetic
- and a splint
 
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BigEasy

BigEasy

.
Jun 21, 2004
2,888
Beneteau 343 Slidell, LA
Ralph Johnstone said:
Purists don't plug the NPS threads of the thru-hull into a ball valve with NPT threads.
Click to expand
Groco now manufactures fittings that all have BSPP threads on the thru hull, valve, & tail piece. Not as good as a “real seacock”; good enough for me. No mis matched threads to be concerned about & it is a legitimate concern. I have changed all my European assemblies to Groco BSPP Over a few years.
 
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M

miraculix

.
Jun 24, 2019
42
Beneteau Oceanis 40 Havre de Grace
BigEasy said:
Why not replace it with the same factory configuration, using Groco thru hull fitting, ball valve, & tailpiece?
Click to expand
That was my plan. Check out the attached picture.

IMG_5323.JPG


Unfortunately, as you can see in the video, it did not work out. There was no way to screw the elbow into the valve, not enough space and you cannot shorten the thru-hull fitting. Groco thru-hull fittings for this valve have a combination thread NPT/NPSM. The first inch or so is NPT and then transitions into NPSM. How do I know this :rolleyes: ? Just cut the fitting to make it shorter, then you will find out. :banghead:
I also thought about a fitting with a BSPP thread, and the corresponding valve may be a solution, but Groco advised against that, stating I would have problems sealing it.
 
M

miraculix

.
Jun 24, 2019
42
Beneteau Oceanis 40 Havre de Grace
Ralph Johnstone said:
Looks like a bit of a sticky wicket.

If you are stuck with two screwed joints, in order to avoid getting screwed yourself, be SURE to use an additional paste sealant with the teflon tape. Something like :

View attachment 231640

Teflon tape by itself on cold fittings is not good, teflon tape and paste sealant is almost 100% guaranteed.
Click to expand
Not entirely sure what I am going to use. Seems to me that there is a discussion about Teflon tape, yes or no. I have this stuff on hand + M3 5200 / 4200

IMG_5296.jpeg
 
M

miraculix

.
Jun 24, 2019
42
Beneteau Oceanis 40 Havre de Grace
I may go with this solution

IMG_5338.JPG


That would probably be the best.
But ... I would have to deal with the stupid recess around the hole and this rim above the hole.

IMG_5324.JPG


Both require some epoxy work, not a problem, but time consuming
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
miraculix said:
Seems to me that there is a discussion about Teflon tape, yes or no.
Click to expand
I have seen it spec'd for refinery work. Tape first and then a light wipe of Permatex #2 on top. #2's claim to fame is that it never hardens. I think the Permatex form-a-gasket products do become solid rubber in time with different resistance to various solvents.

I think the important thing here is never use teflon tape at ambient to lower temperatures without some form of paste. For steam, teflon tape is used by itself. Flows better at the higher temps.
 
BigEasy

BigEasy

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Jun 21, 2004
2,888
Beneteau 343 Slidell, LA
Very frustrating indeed, especially working under the lavatory cabinet. You will have to change the assembly order and get a helping hand. First, assemble the elbow and ball valve such that the elbow is oriented in the proper direction as well as the valve to enable operation of the handle. Once it is dry fitted & is verified, coat the threads with your favorite adhesive / sealer & reassemble. I use 3M 4200 & Teflon tape; however, I don’t want to start the forever debate on what’s the best sealant/adhesive for thru hull fittings! Suffice to say, I have never had a thru hull assembly leak using 4200, including the BSPP fittings & the assemblies can be broken down if necessary. Then, hold the assembly in position & have someone outside the boat thread the thru hull fitting that has been liberally coated with 4200 into the other end of the valve & tighten (Thread your backing nut onto the thru hull, inside the boat, before screwing into the valve). Will probably need a pipe wrench to hold the valve assembly & a step wrench to tighten the thru hull fitting. Finally, tighten the backing nut onto the thru hull fitting to the interior surface of the hull without changing the orientation of the valve & elbow. Let the entire assembly set for a couple of days to allow the adhesive/sealer to cure before attaching hoses & splashing. Going to have to buy another thru hull fitting since you cut yours or may have to resort to all BSPP threads. Let us know how it all works out. Good that you decided to replace the old fitting. If Beneteau can do it, you can too! :)
 
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M

miraculix

.
Jun 24, 2019
42
Beneteau Oceanis 40 Havre de Grace
Thanks for all the input, much appreciated.
@Ralph Johnstone I think I am going to use Teflon tape and some sealant likely from M3, still thinking about it.

@BigEasy The way of mounting you describe is for sure causing the least hassle and would restore everything the way it was. The problem is you need two people, one on the outside, but that should not be a problem. The problem I figured is to tighten down the nut since the nut is sitting in this useless recess. It’s almost impossible to reach it with a wrench. I can hold it with pipe pliers and then turn the thru-hull like in the video, but I am not sure if I will be able to put enough torque on the nut to tighten it down appropriately. I will find out.
Thanks for the encouragement. I am fairly certain Beneteau installed this thru-hull and valve before lifting the complete interior in one piece into the empty hull. I guess the function of the round recess is to create a flat surface for the nut to sit on since the hull is slightly curved in that area and has that rim.
 
JoeWhite

JoeWhite

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Mar 6, 2008
1,342
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
Can you loosen the through-hull nut, then tilt the through-hull away from the wall and finish assembling the seacock and the corner piece, then tighten the nut on the through-hull. This will require the help of a second person from outside.
 
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BigEasy

BigEasy

.
Jun 21, 2004
2,888
Beneteau 343 Slidell, LA
miraculix said:
The problem I figured is to tighten down the nut since the nut is sitting in this useless recess. It’s almost impossible to reach it with a wrench. I can hold it with pipe pliers and then turn the thru-hull like in the video, but I am not sure if I will be able to put enough torque on the nut to tighten it down appropriately.
Click to expand
All of my thru hull fitting locations had the recessed areas, so this wont be the last time you deal with that. I did not have a dedicated wrench to fit the backing nut, so I used vise grip pliers and/or “channel lock” water pump pliers. Also used a pipe wrench (Stilson wrench / “monkey” wrench on the valve body. A thru hull step wrench was used to tighten & hold the fitting from outside the hull. I use only one wrap of teflon tape and 4200 sealer / adhesive. Many use 5200; however, I think that is over doing it.
 
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Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,264
Hunter 310 West Vancouver, B.C.
BigEasy said:
Groco now manufactures fittings that all have BSPP threads on the thru hull, valve, & tail piece. Not as good as a “real seacock”; good enough for me. No mis matched threads to be concerned about & it is a legitimate concern.
Click to expand
So someone beat me to my daydream. Have you seen any literature by Groco outlining this thread arrangement on their thru-hulls? I took a brief look on their site but didn't come up with anything.

The Groco thread arrangement certainly dispells a lot of fears many others and myself have have had for years. I could never see how one could get a reliable thread seal with NPT to NPS but none of my "mismatched joints" from the factory (1998) have ever truly leaked.

Endless articles have been written about mismatched threads. Now I'm wondering how many are truly mismatched.
 
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BigEasy

BigEasy

.
Jun 21, 2004
2,888
Beneteau 343 Slidell, LA
miraculix said:
M3 4200 and tape.
Click to expand
For consideration when you replace the other fittings. I disconnect the hose & grind away the mushroom on the external surface of hull, then pull the remaining thru hull fitting, valve, & tail from inside. Takes all of 5 minutes with no busted knuckles, swearing, etc! Try It, you’ll like it!:biggrin:
 
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