shipbuilding welding v rivets

The only things I've seen on that mention caulking, more or less in passing as if it would be an obvious technique. This post got me thingking about it again and I found a page dealing with restoration of riveted hulls

that shows one method.

Not just ships. If you ever get a chance to see an early steam tractor, you'll see a multitude of rivets holding the steam in. Same with pretty much all early boilers.

I don't know the detals, only that caulking and hot riveting is involved.

Red hot rivets shrink when they get cold.

Thats why you (generally) cannot replace a rivet with a nut and bolt.

And to answer a question that wasn't asked, they used to rivet *boilers* together, too. To make them pressure-tight, they were riveted first (usually hot-riveted, as you describe above) and then they were "caulked."

Caulking a boiler doesn't mean you insert any kind of caulking material. It means you drive a special caulking chisel (I have one) into the edge of the overlying plate, spreading out the edge of the plate and splitting it slightly, and simultaneously turning the split edge under so it bites into the underlying plate.

In effect, you're pre-stressing the joint so that the top plate is sprung into the bottom one, and the top one is digging into the bottom one with a sharp edge. It's very tricky to get a pressure-tight seal that way and it takes a lot of practice, but that's how it was done.

Ed Huntress

On Thu, 29 Jul 2004 22:48:27 -0500, Jim Levie vaguely proposed a theory ......and in reply I say!:

remove ns from my header address to reply via email

Says it all, really, and fascinating it was.

***************************************************** It's not the milk and honey we hate. It's having it rammed down our throats.

caulk also calk (kôk) v. caulked also calked, caulk·ing calk·ing, caulks calks. --tr. 1. To make watertight or airtight by filling or sealing. 2. Nautical. To make (a boat) watertight by packing seams with a waterproof material, such as oakum or pitch. --intr. 1. To apply caulking. --n. Caulking. --caulk"er n.

In the link (from above), they mention chaulking the seam also. Any idea what these tools look like? Could you post a pic of the tool? Just out of curiosity....

Thx Mark

Look up "caulking iron carvel planking" or something like that on Google. I assume you're asking about caulking a conventionally planked wooden boat. I've done it, replacing all caulking below the waterline on a 41' carvel-planked fishing boat. It took me half a summer.

Let me know if you want to know how it's done. The tool looks like a broad chisel, very much like a mason's brickset, except that it doesn't have a sharp edge and the blade is slightly rounded. You use it to drive the oakum and white lead (today, a special loosely-wound rope and synthetic caulk) into the seams. There's more to it than that, however.

If you're talking about a boilermaker's caulking iron, it's a different animal. I have one of those, too. It's like a crank-handled, blunt-edged cold chisel.

Ed Huntress

Ya know when you ask your buddy to pass you the caulk, you really have to make sure you pronounce the "L". Could lead to some very uncomfortable situations on the jobsite.

"Ed Huntress" snipped-for-privacy@optonline.net

Similarly, in caulking soil (CI) pipe, a plumber would first wind ropes/strands of oakham between the bell (flared) and spigot (straight) ends of the pipe, tamp that with what was called a yarning iron (same cranked form as your chisel, but longer blade), then pour in moulten lead, and calk that--both inside and outside of the top of the lead--360 deg around the pipe with a shorter, thicker-bladed, usually cranked caulking iron. There were varitions on the form of the iron, depending on where the pipe joint was located in the structure. (For example, if just below a ceiling, you'd have to use a hooked iron, hit from below the joint.)

Frank Morrison

Especially if you're from Boston

Those old guys had some clever solutions to a lot of tricky sealing problems. Some of them look like they can't possibly work (a boiler held together with rivets, fer chrissake?), but they did. Some of them still do.

Even a perfectly-caulked boat can leak for days, even weeks, after it's put into the water. But pretty soon, it stops leaking -- if the job was done right.

BTW, the sewer pipe in my house is caulked as you describe. It was installed in 1924. No leaks.

Ed Huntress

I took out about ten vestigial feet of the stuff a few years ago. So now I have ten pounds of lead (since made into various gram weights for my balance), around 5 pounds of sulfurous rust in a bucket and 80 pounds of cast iron scrap on hand. ;)

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

IIRC, the real reason the liberty ships broke in half was that many of the welds were 'slugged' and very weak, the welders filled the joint with welding rods and welded a cover over it.