An industrial history question:
I know that most ships were built with rivets before 1930 and somewhere
around there welding took hold. I can understand how welding sheets of iron
together would make for a watertight seal but how were sheets riveted
together made watertight? Seems like the plate joints between the 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
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.
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.
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.
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
"Ed Huntress" email@example.com
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.)
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
BTW, the sewer pipe in my house is caulked as you describe. It was installed
in 1924. No leaks.
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. ;)
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
In shipbuilding, no caulking was used with the rivets. It isn't necessary.
The joints were watertight because of the close proximity of the rivets, the
extreme pressure created when the rivet cooled and that when water ingressed
into the joint and corrosion occurred, the expansion of the oxided iron was
on a ratio of 17 to 1. The expansion of the rust filled all minute voids
that might have been left, effectively sealing every joint. As a matter of
fact, a riveted joint is much stronger than a welded one. This was an
expensive lesson learned during the second world war when many of the new
liberty ships literally broke in half. To this day the hull to deck joint is
typically riveted on new ship construction.