New Seacock install - Sequence of Installation? Help.

[Cdn_bacon]

So I decided to take on a project and start replacing some seacocks. (2) 3/4" and (1) 1.5" They're in a tight space up against a vertical bulkhead. Old ones that came out were thru hulls with an inline ball valve. Going back I decided to install a fiberglass backing plate and flanged seacocks. I think I have this figured out a but need a sounding board so I don't make a mess of things.

First. The new seacocks with 90's installed on top won't be able to spin down on the thru hull due to proximity to an adjacent bulkhead. Same issue with installing the valve first and then trying to install the 90 after so it has to go in as one assembly.

Backing plates are similar to the groco pre-made plates with flange bolt holes already drilled. Hole in center is slightly oversized to accommodate 2 different size valves.


First: Install the backing plate with epoxy to the hull. Wax TH, insert TH and then flanged valve so the plate is centered correctly. Allow to setup, remove valve and TH.

2nd: Apply 4200 to bottom of flange on new seacock. Place onto backing plate and thread in TH from outside. Back inside, install bolts to flange to backing plate. Tighten. Back outside and remove TH, clean with acetone.

3rd: Apply 4200 to the bottom of the TH and mushroom head. Insert into the hole. Tighten.

I believe this aligns with the guide from Marine Sail How To.

Question though: I've seen Marine Sail post in other forums on needing to install teflon with pipe dope for fittings but nothing in his guide for installing new seacocks. So do I need teflon or pipe dope on the TH to valve? Or only from the valve up?

If I do need pipe dope, how do I get it on the threads and insert without contaminting the fiberblass before the 4200 makes contact with it?

The only other thing I could change would be the elbow. I could use a street elbow which is vertical and then a NPT to hose fitting and piece mail it all after the seacock is installed? This would allow me to push the TH in first, apply pipe dope to the top of the TH and then screw the seacock down onto the TH and minimize turning the TH. That being said, this is a tight space to get into which involves being inverted and I can only get one arm to the valves for any assembly work. Not preferred at all as its more fittings and more things to leak although.


I feel like I'm over complicating this but wanted to pick the brains of those who are much more experienced than me.

[tkeithlu]

QUOTE: "First. The new seacocks with 90's installed on top won't be able to spin down on the thru hull due to proximity to an adjacent bulkhead. Same issue with installing the valve first and then trying to install the 90 after so it has to go in as one assembly."

I think that I followed you. The core of the issue is this problem. Your goal is to clamp the exterior mushroom to the interior assembly, with 4200 between the two, making a very strong assembly and a problem for whoever might want to remove it all in the future. You have two ways to do that:

1. Cut slots in the mushroom so that you can turn it, threading it up the interior part, with both parts covered in generous amounts of 4200. Clamp the interior part to the mushroom with the hull in between. Clean up the mess and wait a week for it to harden.

2. Drill the interior flange and the mushroom for six spaced bolts that clamp the mushroom to the interior flange with the hull in between. Ditto. The bolts should also go through holes in the hull.

In both cases your mushroom and your interior flange need to be wider than the existing hole in the hull, not only as wide as something you've built up. If that poses a problem, then:

3. Mount the through hull on a suitable structural board, and bolt it to the hull on the outside, fairing the edges.

These approaches are simpler than what I think I am reading in your description. In all cases, you goal is structural integrity. Remember the fifty pound test: The valve should withstand a fifty pound weight applied at 90 degrees, or to the side in your case.

Good luck with it.

[Bowdrie]

Originally Posted by Cdn_bacon

First. The new seacocks with 90's installed on top won't be able to spin down on the thru hull due to proximity to an adjacent bulkhead. Same issue with installing the valve first and then trying to install the 90 after so it has to go in as one assembly.

Please, do not install a seacock such that the top/adaptor fitting cannot be installed or removed.
You use fittings such as these from Sparatn.
I believe that Groco also makes "swivel 90s".

https://www.spartanmarine.com/all-pr...adapters-parts

[HopCar]

Bowdrie is right. Those fittings would solve your problem. Unfortunately they won’t work on most of the seacocks made today. They need a straight male thread on top of the seacock.

I think Spartan is the only company still making seacocks that way. Of course you could do a lot worse than using Spartan seacocks.

[Bowdrie]

Originally Posted by HopCar

They need a straight male thread on top of the seacock.

You're right, I stand corrected.
Yeah, common valves used today whether flanged or not all seem to use a female thread.
One would need some kind of adaptor.
Regardless, one needs to be able to remove any threaded fitting from the seacock/seavalve without having to remove the valve from the hull.

[osprey877]

Originally Posted by Cdn_bacon

2nd: Apply 4200 to bottom of flange on new seacock. Place onto backing plate and thread in TH from outside. Back inside, install bolts to flange to backing plate. Tighten. Back outside and remove TH, clean with acetone.

What are the bolts threading into? Are there captured nuts in the backing plate, or??

[SVTatia]

I had the same problem with a seacock near a bulkhead. I cut a bit of the 90, and it still had a good piece for the hose grab.
After that I only needed another 1/4 inch, so I "carved" 1" x 1/4" of the bulhead followed by a coat of epoxy. This allowed me to turn the 90 on to the seacock.

[SVTatia]

Originally Posted by osprey877

What are the bolts threading into? Are there captured nuts in the backing plate, or??

Or as per Mainesail, bronze studs threaded to the backing plate?

[Cdn_bacon]

Originally Posted by Bowdrie

You're right, I stand corrected.
Yeah, common valves used today whether flanged or not all seem to use a female thread.
One would need some kind of adaptor.
Regardless, one needs to be able to remove any threaded fitting from the seacock/seavalve without having to remove the valve from the hull.

Why? Boat is seasonal and comes out every winter. Original seacocks lasted 36 years so I figured these should last the length I will own this boat (10+ years) or else I can remove in the offseason etc.

To your comment though:
1.) The old original valves were a TH to a inline ball valve to a street elbow to a NPT to hose fitting.
2.) I could go to a straight NPT to hose although my current hoses would not be long enough and I'd have to install new hoses and they would be in the way of functioning the valves due to compartment access.

[Cdn_bacon]

Originally Posted by SVTatia

Or as per Mainesail, bronze studs threaded to the backing plate?

1/2" backing plates have holes that are drilled and tapped to screw into.

[Cdn_bacon]

Originally Posted by osprey877

What are the bolts threading into? Are there captured nuts in the backing plate, or??

1/2" backing plates have holes that are drilled and tapped to screw into. See attached pic.

The 2 valves shown are the 3/4". The hole to the left is for the 1.5" and there is a bulkhead behind and to the left (not shown) which is where it would hit.

[jamhass]

1. A small amount of pipe doe on the first couple of female threads on the seacock, similarly a bit on the first couple of male threads on the mushroom. Wipe off any excess. Assembly will distribute the dope without much (if any) excess. No contamination worries.

2. Use a thru-hull wrench to tighten.

Personally (and I have done this several times) No need for multiple dry or semi-dry reassemblies. Dry fit all as needed, making sure the backing plate and hull area fit well, sanding/grinding the backing plate to fit well and clean thoroughly. Goop the threads with pipe dope, 4200 the mating surface of the mushroom (the area where it meets the hull, not the threads), add epoxy to the hull and backing plate. Assemble and tighten. Done.

[Cdn_bacon]

Originally Posted by jamhass

1. A small amount of pipe doe on the first couple of female threads on the seacock, similarly a bit on the first couple of male threads on the mushroom. Wipe off any excess. Assembly will distribute the dope without much (if any) excess. No contamination worries.

2. Use a thru-hull wrench to tighten.

Personally (and I have done this several times) No need for multiple dry or semi-dry reassemblies. Dry fit all as needed, making sure the backing plate and hull area fit well, sanding/grinding the backing plate to fit well and clean thoroughly. Goop the threads with pipe dope, 4200 the mating surface of the mushroom (the area where it meets the hull, not the threads), add epoxy to the hull and backing plate. Assemble and tighten. Done.

Thanks! About to drill out an existing hole from a 1.25" TH to accommodate a 1.5". Should be tight with out too much slop but is there too tight?

[SailingHarmonie]

Yeah... if it's not you, whoever has to actually service this seacock in the future will be damning you to a very dark corner of hell if you install it as you are planning. Kind of like you are doing right now for the builder of this boat. This is not a ball you should kick down the road for some else to deal with your problem.

I know this is thinking a bit outside the box, and there are many reasons it might not work in your physical situation, but consider putting a hole in the bulkhead to give you room to thread on the 90. It would have no real impact on the strength, but let you install things in something close to the "right" way.

[SVTatia]

Originally Posted by SailingHarmonie

...
but consider putting a hole in the bulkhead to give you room to thread on the 90. It would have no real impact on the strength, but let you install things in something close to the "right" way.

This is what I had to do, but my bulkheads are 1" thick I just carved it a bit with a multi-tool.