Leaking Ball valve

[Honeymoon 26]

Good Morning, I and about to replace a leaking ball valve on the toilet waste side.The handle spindle shaft broke and it is leaking a little bit. I am going to do it in the water, anyone have any tips.

[Kokanee]

OOOh - You are a braver man than me.

I wouldn't do it, unless there were no other options. I expect it is a 1 1/2" thru-hull so it will flow a lot of water. Have a big pump ready to go. Preferably an AC pump or diesel/petrol. Make 100% sure the new valve is the correct size and thread type. Have your thread tape ready. Don't try to install the new valve with the ball shut. Have it open until you get a couple turns on it. Don't do it by yourself.

Good luck.

[Sherpa17]

In some ways, it's like cleaning the speedo. But could you maybe plug it from the outside?

[Bill O]

Looks like plenty of room to tap in a wooden plug or rubber stopper from the outside. Best would be to have a proper size of one of these expansion stoppers and tighten it up in spot.

Would be a good idea to have an appropriate sized pump handy, just in case.

A quick question, why is there a hose clamp near the nut of the thru hull?

[rbk]

If accessible get someone to slip a plastic garbage bag over the thru hull on the outside while opening it on the inside, the pressure will hold it in place, it will leak a bit but way less than just letting it go. Plastic bags are excellent at stopping engine water flow lol.

[sailormed]

Buy a "Seabung" and you will have peace of mind when unscrewing the ball valve. Soft rubber inserted from inside the hull in the throughull.

[Sherpa17]

This is brilliant.

Originally Posted by rbk

If accessible get someone to slip a plastic garbage bag over the thru hull on the outside while opening it on the inside, the pressure will hold it in place, it will leak a bit but way less than just letting it go. Plastic bags are excellent at stopping engine water flow lol.

[Manateeman]

I would start with the worse case possible and that begins with the thru hull...the nut and the threads...nothing to do with the ball valve on top.
There are a number of things you can stick into the thru hull from the outside of the hull...let’s go nerf ball. OK...now you need to prevent the thru hull from turning while you unscrew the valve. So you have one big pipe wrench on the thru hull and one on the valve. This messes up the threads on the thruhull and makes it a real problem to remove the nut. The thru hull can collapse, break off, split and leak while you are trying to unscrew the valve. Trying, because you might not be able to do it at all. Some come off easily, some with a lot of heat, but sometimes, the thru hull has to be cut. Now you have to install a new thruhull.
That’s if you can get it out...after splitting the nut and sometimes cutting the thruhull into segments with a saws all.
Two divers and somebody inside can change a thruhull if...and it’s a big if...the valve unscrews ok while the divers hold it from the outside with an internal wrench and...the thruhull nut moves easily so it can be unscrewed.
It can be done.
Would I put a wrench on a ball valve inside the boat without a diver ? Nope.
My wife and I have switched out shaft seals without me diving over. We’ve changed entire removable depth finders that needed to be hammered out.
Lots of fun if you know how to work with a face mask on inside the boat.
I’d go watch somebody do battle with a thruhull in a boatyard. Maybe you can find a spot to lay the hull over at low tide.
Groco adaptor plate. Marelon thruhull, commercial ball valve. Lots of 5200, Tef-Gel and a travel lift. Even manatees come up for air every 15 minutes.
Happy trails to you.
Captain Mark and his PADI professional manatees

[HopCar]

No matter what you do now, install a real flanged seacock next time you haul. That set up scares me. There is way too much unsupported thru-hull. Another problem is that the tapered threads on the ball valve won’t engage the straight thru-hull threads more than a couple of turns. The whole thing is very weak.

[Uncle Bob]

Timber plug whacked in from outside, the ball valve has thread tape on the thread so it should unscrew relatively easily, on with the new with thread tape, reconnect hose with new good quality hose clamps and remove bung. Job done.
Been there done that.
Noticed that there doesn't seem to be a backing block on the hull under the through hull fitting nut, next time it is out of the water at least install one correctly if you don't go the path HopCar suggested.

[Manateeman]

A poster has commented the thru hull might have had Teflon tape on it but I don’t see that from the photo. Teflon tape has nothing to do with what is going on here. In thus case, it looks like some idiot screwed a ball valve onto a thru hull directly. The thru hull threads are straight not tapered and the ball valve is tapered thread. The above poster is completely correct.
It’s a seriously bad installation.
Mismatched threads result in an incredibly weak joint...a few threads will jam up together...not screw together at all.
Any suggestion that you can reuse the thruhull will only result in a serious failure. Period. It’s just a matter of time and the corrosion keeps weakening the metal where it is jammed together.
A backing block will not cure this mismatch of threads. You cannot thread a tapered thread ball valve onto a straight thruhull...you can jam it together but that is not how tapered joints achieve a seal.
The uppermost threads of the thruhull are probably mashed and therefore it will difficult if not impossible to get the nut past them. This makes it impossible to screw down a Groco adaptor plate. If you do this in the water you need two very experienced divers who have done this before and an assistant, all the right new parts and a lot of luck...you need to keep the sea out while you hacksaw and punch out the old thruhull. Easier said than done. There is no way you are going to simply screw another ball valve onto this thruhull. No way.
Straight threads don’t screw into tapered threads. Period.
Happy trails to you
Captain Mark and his get out the crash pump manatees

[Uncle Bob]

Originally Posted by Uncle Bob

Timber plug whacked in from outside, the ball valve has thread tape on the thread so it should unscrew relatively easily, on with the new with thread tape, reconnect hose with new good quality hose clamps and remove bung. Job done.
Been there done that.
Noticed that there doesn't seem to be a backing block on the hull under the through hull fitting nut, next time it is out of the water at least install one correctly if you don't go the path HopCar suggested.

No mention of thread tape on the thru hull nut, just the end that has the ball valve fitted!!

Originally Posted by Manateeman

A poster has commented the thru hull might have had Teflon tape on it but I don’t see that from the photo.(That would be the white stuff wrapped around the thread where the ball valve is fitted.) Teflon tape has nothing to do with what is going on here. In thus case, it looks like some idiot screwed a ball valve onto a thru hull directly. The thru hull threads are straight not tapered and the ball valve is tapered thread. The above poster is completely correct.
It’s a seriously bad installation.
Mismatched threads result in an incredibly weak joint...a few threads will jam up together...not screw together at all.
Any suggestion that you can reuse the thruhull will only result in a serious failure. Period. It’s just a matter of time and the corrosion keeps weakening the metal where it is jammed together.
A backing block will not cure this mismatch of threads. You cannot thread a tapered thread ball valve onto a straight thruhull...you can jam it together but that is not how tapered joints achieve a seal.
The uppermost threads of the thruhull are probably mashed and therefore it will difficult if not impossible to get the nut past them. This makes it impossible to screw down a Groco adaptor plate. If you do this in the water you need two very experienced divers who have done this before and an assistant, all the right new parts and a lot of luck...you need to keep the sea out while you hacksaw and punch out the old thruhull. Easier said than done. There is no way you are going to simply screw another ball valve onto this thruhull. No way.
Straight threads don’t screw into tapered threads. Period.
Happy trails to you
Captain Mark and his get out the crash pump manatees

Funny, I didn't see any suggestion either from myself or the original poster that the thru hull be changed, just the failed ball valve on top.
But then again, perhaps my comprehension and literacy is failing along with my eyesight.

[Manateeman]

You cannot change out the ball valve alone. Period.
The white stuff could be anything. It doesn’t matter.
Once you jamb a ball valve (tapered threads) onto a thru hull (straight threads), the thru hull threads are wrecked. You get just a few threads with poor contact area and little strength the first time you do this...the second time it becomes even weaker. These are simply the facts not an opinion.
I don’t care how many times you quote me because this is not a case of another way to do the job. It’s a case of giving bad advice...really bad advice.
The subject is explained on line in the “Marine how to “ on seacocks.
It’s explained in the Groco literature.
It has been explained time after time on this forum.
Jamming a ball valve onto a thruhull is a really dangerous idea.
It’s unconscionable to recommend it.
Captain Mark

[Uncle Bob]

Originally Posted by Manateeman

You cannot change out the ball valve alone. Period.
The white stuff could be anything. It doesn’t matter.
Once you jamb a ball valve (tapered threads) onto a thru hull (straight threads), the thru hull threads are wrecked. You get just a few threads with poor contact area and little strength the first time you do this...the second time it becomes even weaker. These are simply the facts not an opinion.
I don’t care how many times you quote me because this is not a case of another way to do the job. It’s a case of giving bad advice...really bad advice.
The subject is explained on line in the “Marine how to “ on seacocks.
It’s explained in the Groco literature.
It has been explained time after time on this forum.
Jamming a ball valve onto a thruhull is a really dangerous idea.
It’s unconscionable to recommend it.
Captain Mark

Captain, just for some clarity, at no time was it said that it was an ideal solution, however it is a solution to a pressing problem.
For example both the parallel and taper versions of 1.5 inch BSP threads have a thread count of 11TPI, the drill size for the BSP thread is 45.5 mm, the BSPT thread is 44.5mm, so 1mm difference over the entire thread.
With the same thread count there will be no "mashing of mismatched threads", the taper will tighten on the top threads of the parallel, it will not be as strong or ultimately as safe as BSP to BSP or BSPT to BSPT however a bulk of the threads will engage, though not ideally. I have previously noted that the original appears to have been fitted using thread tape which facilitates removal of the old without damaging the threads, though I suspect that it was used to prevent leaks rather than enhance removal.
To say that it is "jamming a ball valve onto a throughull" is not correct nor is it"really dangerous". Many thousands of vessels world wide have valves fitted thus and while I admit it is not ideal, in many places it is common practice.
If I remember correctly Maine Sail actually acknowledges this in his article.
By all means google and quote all the sites that you wish, it doesn't change the fact that the practice is common in many places without the catastrophic consequences you predict will happen.
Cheers.

[Uncle Bob]

Cute isn't it, I have been deemed dangerous, unconchable and downright wrong by offering a solution to the question posed here. Well Capn, I am also practical, pragmatic and literate, so feel free to include any advice and comments openly here.
Oh and for what its worth the details about me, my boat and location are displayed beside each and every post of mine.