Ball valve & thruhull

[Rocinante33]

This weekend I was in the process of wrapping up a long & tedious series of projects. The last of these was changing hoses to the engine (Universal M25). Upon completion, I turned the marelon ball valve for the seawater inlet. It resisted, then gave way & seemed to turn too easily. The shaft to the handle had broken. No water came through when I started the engine. It is in the closed position. It is probably a factory original.

We just had the boat hauled & bottom painted. I would rather not haul it again just yet. I would rather defer relacing it with a proper seacock until the next haulout.

This is what I propose to do:
1. Call Forespar (Marelon makers) to check feasability. Can I do this as far as they are concerned?
2. Dive the hull & lightly drive a soft wooden plug into that thruhull. Allow it to soak & swell for an hour (or even overnight?).
3. With additional wooden plugs standing by, remove the bad ballcock from the thruhull threads.
4. Replace it, sealing the threads as I do so.
5. Inspect carefully to ensure that the thruhull has not spun or otherwise begun to leak.

Sanity check----over
Keith
E33

 

[Guy Stevens]

I have drilled a couple of thru hulls in the water

You can do a lot of things here, I have even gone so far as to drill and mount a thru hull and valve in the water.

A good bowl, with a toilet ring attached with the lip, planted on the outside of the hull will keep most of the water out. If you have everything ready it is really not a huge deal. A rag stuffed in from the outside will do more than you can guess.


Having done this a number of times the keys are to have everything ready that can possibly go wrong, including some bigger wooden plugs. Now mind you I have never done this when I though there was the slightest chance of anything going wrong.

Guy

 

[Shadowfax]

On my 34 the raw water intake has a cast bronze screen flush with the hull that would preclude using a wood peg. A nice piece of vinyl might do the trick

 

[chtaylor]

I just spoke to a diver last week about changing a thru-hull in the water. He told me he uses two people (one inside and one in the water) and an old fashioned toilet plunger against the outside of the hull to keep the water out.

As I recall, he said that he applies the plunger over the thru-hull while the inside person removes the valve, fittings and nut. Then, while the insider blocks the water with his palm, the diver removes the plunger, removes the thru-hull and replaces the plunger.

The next step is to give the diver the new thru-hull already with bedding compound. The diver then removes the plunger and inserts the thru-hull while the insider uses his palm to keep as much water out as possible.

The diver replaces the plunger and leaves it in place until the insider re-attaches the nut, valve and fittings.

Good Luck,
Charles Taylor

 

[Guy Stevens]

Yeah what Charles said

We have done it with a plunger too. The bowl allowed us to drill through the hull without drilling the diver or the plunger if we are installing a new thru hull. This extra space would not be needed if we are only doing a replacement.

Guy

 

[rwthomas1]

Does he really need to change the thru-hull part of the assembly? If its just a ball valve on a standard mushroom type thru-hull, with the valve just threaded onto the threaded thru-hull shank..... Couldn't you simply plug the thru-hull from outside with a wood plug or a large glob of plumber putty and then twist off the old valve, screw on the new and away you go? I understand a flanged seacock would likely not work this way though.... Just curious. RT

 

[Rocinante33]

mo' thruhull

Wow, interesting! As Rob inferred, though, I only propose to replace the ball valve at this time, not the thru hull. I want to leave the thruhull as-is until my next haul out. Then I will use a proper flanged seacock, perhaps ala Loren's project.

The bowl or the toilet plunger sound like either would work to prevent inflow during the change. I think I am more inclined to use the tapered plug, though, and I like the idea to add a bit of plumber's putty.

I would think that changing the thruhull as Charles' diver has said would get a lot of water in the boat. As soon as the flange pulls away, water will flow in around the threads. Guy, you must mean installing a flanged seacock if you are talking about drilling holes in the hull. That sounds like desperate measures!

BTW, Forespan gave me a thumbs up. It may be 1 week before I try it. Meanwhile, I'll get the new ball valve.

Thanks a lot, everybody!
Keith
E33

 

[Guy Stevens]

Wait....

If you are not changing out the thru hull there is going to a possible issue with the thru hull turning while you try to undo the existing valve.

In that case the diver needs to have a thru hull wrench handy. It also blocks a lot of the water coming in. If you put some plumbers putty on it, even less water gets through.

Sorry for not mentioning that in the first post. Things are nicely busy here, and I am mostly tired when writing.


Guy

 

[Mark F]

I just replaced the (stuck open!) head outflow gate valve with a ball valve two weekends ago. I used the tapered plug method and had no problems. We also cranked the boat (our new E27) over using the main halyard so I could get to the through hull from the dock. As it turned out it could have done without heeling the boat. I ended up with not quite 1/2 cup of water inside. And most of that was from disconnecting the hose.

 

[Rocinante33]

Ball valve changed

Just to update & close the issue on this, I could not use a tapered plug because there is a strainer on the inlet. So I took some advice given here and used an old style red rubber toilet bowl plunger. I dove & slapped it on there. It worked like a charm. I'll bet I didn't even get more than 5 drops of seawater in the boat!

Changed the ball vall & back in business! I didn't find a thru hull wrench anywhere, so I took a chance it wouldn't turn & I lucked out. The thru hull did not turn & no leaks are observed.

Keith