Thru hull ball valves

Local hardware store? Any feelings on brand or material type?

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Greetings,
Mr. GR. Bronze and thru bolted.


Just saw Mr. FF's post. Tapered valve WOULD be better than ball.

Ball valves are OK for closing an opening that is at least 1 ft above the healed waterline.

For underwater a thru hull and ball valve SUCK.

Every underwater opening needs a SEACOCK, which are bolted to the hull with at least 3/8 bronze bolts.

Second the thru hull has straight threads (so it can be trimmed and screwed into a seacock) and ball valves have tapered National Pipe Threads.

Straight and tapered will catch and mate for a couple of turns , but offer no support .

Seacocks come in a number of varieties , the tapered plug bronze are best as they can easily be reseated when required.

How the SS balls and plastic contacts fare after decades in sea water is yet unknown.

Caviat Emptor!

Marine bronze ball valves have straight threads to match up with the thruhull and tapered threads on the outside to screw in a bronze hose barb fitting. Normal hardware stores don't sell these- mostly brass which is no good in seawater.

Apollo makes them and you can buy them from West Marine, Defender, etc.

"Real" seacocks where the valve body is integral with the thruhull are better, but if you are just looking to replace an existing installation, buy a marine bronze ball valve.

I have seen chrome plated bronze balls and stainless steel balls and stainless steel with Teflon seats seem to hold up best.

This is a link to a good tutorial on seacocks and ball valve replacement: Replacing Thru-Hulls and Seacocks Photo Gallery by Compass Marine How To at pbase.com

David

Thanks David,
I need to address the through hull issue myself as mine is leaking. I don't have a ball valve but the "proper" type.

There was a really good link to a picture walk through for re-seating the tapered valve shaft and I intend to find it.

Now if I can figure out how to release my locking intermediate bearing I'll be good.

Oh ... Not so. I need to know how to put a hole in my bronze rudder to extract the shaft. Hole saw comes to mind. Do they make hole saws for metal? Dropping the shoe all the time is getting to be a drag. Ideas to plug the hole may be a great advantage too. And by plugging I mean a removable plug.

RTF

Even the nice one you pictured doesn't have a stainless handle. All that type on my boat and ALL of the handles are rusted, in some cases so bad that I won't rely on the integrity of the handle and use a wrench when working the handle.

"Marine bronze ball valves have straight threads to match up with the thruhull and tapered threads on the outside to screw in a bronze hose barb fitting."

Dave, that statement is a little confusing. Only the valves with flanges, like the one in RTF's post, have threads as you describe.

I don't know of any non-flanged valves that have a straight thread at one end and tapered at the other.

It is best to follow FF's advise and just use a flanged seacock from a known manufacturer. I would have no problem using a flanged seacock from Groco, Apollo, Perko, or Buck-Algonquin on my boat.

If you want to be able to easily change the valve, you can add a flange to a regular ball valve by using a Groco Flanged Adapter.

Marine Hardware

Marine Hardware makes this option. Why couldn't one connect a ball valve to this directly?

HIGH SPEED WATER PICKUPS
Cast from bronze with extra-sturdy wall thickness. Our pickups have a generous neck length to fit any hull and have straight pipe thread blending into tapered pipe thread at end for easy connection to piping or valves. Complete with flanged jam nut

BDofMSP said:

Marine Hardware makes this option. Why couldn't one connect a ball valve to this directly?
Cast from bronze with extra-sturdy wall thickness. Our pickups have a generous neck length to fit any hull and have straight pipe thread blending into tapered pipe thread at end for easy connection to piping or valves. Complete with flanged jam nut

Click to expand...

With a solid glass hull and backing plate, it wasn't a problem, not so sure about a cored hulls though. Marine Hardware's thru hull fittings are excellent and the blended threads resolve the issue of pipe vrs. tapered thread designs. I replaced all my factory gate valves with their bronze seacocks and ball valves.

manyboats said:

Oh ... Not so. I need to know how to put a hole in my bronze rudder to extract the shaft. Hole saw comes to mind. Do they make hole saws for metal?

Ideas to plug the hole may be a great advantage too. And by plugging I mean a removable plug.

Click to expand...

Yes Eric, standard bi-metal hole saws work great cutting metal. I used a 2 1/2" diameter one recently to broach a hole through a 1" steel plate.

Why not just use a zinc to plug the hole if you feel it would be that big a deal.

As to the subject of the thread, the one thing my previous owner installed that I do not like is a brass ball valve from Home Depot. A proper through bolted tapered bronze sea cock will be installed at the next haul out.

Thanks all, i replaced mine with a hardware store valve....will remove and replace wih a marine valve. The thru hull is in gpod shape and I will leave it alone. Thanks for all the help

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CPseudonym said:

Yes Eric, standard bi-metal hole saws work great cutting metal. I used a 2 1/2" diameter one recently to broach a hole through a 1" steel plate.

Why not just use a zinc to plug the hole if you feel it would be that big a deal.

Click to expand...

Yup. Lobstermen do this all the time. Cut a hole. Clamshell zinc.

Now, my question is can one do this with a fiberglass, slightly airfoiled, rudder?

dwhatty said:

Yup. Lobstermen do this all the time. Cut a hole. Clamshell zinc.

Now, my question is can one do this with a fiberglass, slightly airfoiled, rudder?

Click to expand...

I can't see why not. The rudder will likely have a core of some sort, so the edges of the hole will need to be sealed to prevent ingress of water. A short piece of PVC pipe might do the trick. With creative use of glass matt and gellcoat the circular piece removed could be made into a removable plug. This would, of course, have the same convex surfaces as the rudder itself.

"Marine Hardware makes this option. Why couldn't one connect a ball valve to this directly?

HIGH SPEED WATER PICKUPS
Cast from bronze with extra-sturdy wall thickness. Our pickups have a generous neck length to fit any hull and have straight pipe thread blending into tapered pipe thread at end for easy connection to piping or valves. Complete with flanged jam nut"

If you install it with a nice thick backing block so that only the tapered threads are exposed, that should be fine. You don't want a long unsupported thru-hull sticking up. They can and do get broken off.

Some say seacocks should be bolted to the hull, others say bolting to the backing plate is sufficient. Thoughts on that?

On The Rocks said:

Some say seacocks should be bolted to the hull, others say bolting to the backing plate is sufficient. Thoughts on that?

Click to expand...

It's not bolting it down that's as important as the thinness of the threads of a ball valve just screwed onto a thru hull.

It's a system, not just a component, and you have to look at the weakest component. A ball valve screwed onto a thru hull with or without a backing plate, bolted or screwed or glued down is still probably stronger than the thickness of what is left of the thru hull pipe after they turn threads in it. screw on a ball valve, add a few years of erosion/corrosion inside and then apply a lateral force on the hose about 2 feet above that set up and see what fails pretty easily...the threads below the valve that's supposed to keep the water out.

I went with the Groco flange with appropriate ball valve screwed on top...much heavier duty and knowing that the ball valves with or at least might eventually need replacing due to the wonders of newer tech.

I believe its the easier more cost effective setup.

On The Rocks said:

Some say seacocks should be bolted to the hull, others say bolting to the backing plate is sufficient. Thoughts on that?

Click to expand...

Good question? I'm assuming my seacock bolts are through the backing plate and then the backing plates were laminated to the inside of the hull, since the bolt heads don't appear on the outside of the hull?? I've often wondered what i would do if the bolts needed to be replaced or re-positioned.

When we purchased the boat it had no bottom paint and it didn't look like they were somehow counter sunk through the hull and the hole filled either?? But they're very solid and not going anywhere!!

"Some say seacocks should be bolted to the hull, others say bolting to the backing plate is sufficient. Thoughts on that? "

If the backing plate is glassed to the hull, I wouldn't have a problem bolting the flanged seacock to the backing plate.

Another way to do it is to bolt the backing plate through the hull and bolting the seacock to the backing plate.

I think the traditional way is to have the bolts go through the hull, backing plate, and Seacock Flange.

Groco is now selling pre-made backing blocks with threaded inserts installed in them.

The fear is a 300lb crew will stomp on the thru hull , or an errant tool box will crash it.

If you think a glued in place backing plate can handle the load , thats all it takes.

On a racing sail boat the loss of bolt heads night make a quicker boat, for most motorboats , even the semi plaining , I doubt it.

FF summed up the problem nicely. You want to prevent a side load on the threaded thru-hull fitting.

If I were installing one today, I'd use the Groco backing block bedded in epoxy and through bolted to the hull. I might use flat head machine screws instead of hex head if I wanted to keep the hull smooth, but like FF said, it really doesn't matter.

I'd use a Groco Flanged Adapter bedded in 5200 and bolted to the threaded inserts in the backing block.

Then I'd screw Groco ball valve onto the Flanged Adapter with a good bronze hose barb in the other end.

With a setup like that, the thru-hull fitting could rot away and you wouldn't even know it until the next time you inspected the bottom.