Thru hull integrity

[Scott T-Bird]

This thru hull is an after-market installation to provide raw water to the pump serving the reverse cycle heating/cooling system. It is in an awkward location under the aft berth platform where I have to reach underneath from a side opening. The handle is so stiff that I can barely open and close the lever. I have to push so hard that I worry about the leverage at the pipe junction with the hull. I am uneasy about the lack of a backing plate or any other reinforcement.

Consequently, I never close this valve under any normal circumstance (except to replace the hose in this circumstance). I recently replaced the pump and all the plumbing & hoses. The boat is in the water so I'm not planning to change this thru hull this season but I am thinking about cutting an access hatch directly over the valve. And I think I may replace the thru hull next time the boat is out of the water. See any glaring problems? This installation could be 25 years old.

 

[NYSail]

I feel your pain. I had the smart idea to replace a few this season. the primary one that I wanted went in with no problem however, the other two it’s a little more precarious because of the size of the fittings and the space I’m working with. I’m going to have to screw from the outside into an already assembled fitting. This is contrary to what I typically do. I usually put the skin fitting in, let it cure and then build up upon it. So I have a question instead of using piped dope or Teflon tape what about using 4200 on the threads? the gentleman at Groco said if you have some why not…. I’m thinking the primary to be the 4200 let it sit and cure and then I have a solid fit. Not trying to hijack your thread, but I’m looking at options to make these fittings go easier when we’re in a tight space. It makes sense right??

thanks!
Greg

 

[NYSail]

 

[jssailem]

Seeing the color on the "through hull" portion, I would replace it. It has been there for 25 years, as you state. Seems like you owe it nothing. It has served its purpose and is better to replace it than wait until it fails. At least if it were my boat.

 

[dlochner]

This thru hull is an after-market installation to provide raw water to the pump serving the reverse cycle heating/cooling system. It is in an awkward location under the aft berth platform where I have to reach underneath from a side opening. The handle is so stiff that I can barely open and close the lever. I have to push so hard that I worry about the leverage at the pipe junction with the hull. I am uneasy about the lack of a backing plate or any other reinforcement.

Consequently, I never close this valve under any normal circumstance (except to replace the hose in this circumstance). I recently replaced the pump and all the plumbing & hoses. The boat is in the water so I'm not planning to change this thru hull this season but I am thinking about cutting an access hatch directly over the valve. And I think I may replace the thru hull next time the boat is out of the water. See any glaring problems? This installation could be 25 years old.

View attachment 237662

It's a ball valve which is good. It does not have a flanged base, which is bad.

The absence of a flanged base and the exposed threads make this a very weak through hull fitting. The problem with exposed threads is the pipe wall thickness, the valley's in the thread weaken the pipe. That's not an issue when the threads are buried in the female fitting, it is when you have a lot of exposed thread. You are correct to be concerned about breaking it while trying to open or close the valve.

 

[NYSail]

These are the new……. The one with green is a valve I replaced 2 years ago. All on the outside. Value and inner are like new.

 

[NYSail]

So what are your thoughts on 4200 exclusively on the stem of the skin fitting going into the valve rather than Teflon tape / sealant?

 

[dlochner]

So what are your thoughts on 4200 exclusively on the stem of the skin fitting going into the valve rather than Teflon tape / sealant?

4200 is probably overkill and will make removing the fittings more difficult. I prefer pipe dope over teflon tape because it is easier to apply, especially in tight quarters. If 4200 is used on the through hull fitting logic would dictate that it be used on all below the waterline joints in the system as they are all subject to hydrostatic pressure and possible leaks. The frugal sailor thinks there are better places to spend money.

 

[NYSail]

On all my fittings I use pipe dope and never an issue. However on this one fitting it’s a 45 degree fitting off the hull and it has to be in a perfect orientation for the valve. When set in place I have 3/4 more of a turn to be fully snug on the threads. Twisting back leaves it too loose for my comfort…….. did wraps of tape and dope and just still moves with a little pressure. Figure I will just use the 4200 and be done with it. Last fittings and valves lasted 21 years…… don’t think I’ll have to remove this one ever. Just don’t want a leak or a fitting that can move if too much pleasure.

 

[jssailem]

So what are your thoughts on 4200

 

[dlochner]

However on this one fitting it’s a 45 degree fitting off the hull and it has to be in a perfect orientation for the valve. When set in place I have 3/4 more of a turn to be fully snug on the threads.

That's the problem with tapered NPT threads, unless they are completely tight they will leak. In this case a more aggressive approach is necessary.

 

[Barnacle Bill]

You might try lubricating the valve to get it to work. It is seized and maybe some product will un-seize it.