Caulking Talk

San Francisco Maritime National Historical Park


Welcome to the ship Balclutha. Here in the National Park Service, San Francisco Maritime, we're getting ready for the rainy season, and for ships that means caulking the deck. We want to make sure that our deck is tight, all our planks are tight, and basically caulked into a single diaphragm that is waterproof throughout the season - and yet flexible. To do that - I'll give you a quick view of a cross section of what one of these deck planks looks like. You can see that it's chamfered with a wedge, and we use two different types of fiber material. We'll lay in a layer of cotton, followed by a layer of oakum. And each successive layer of fiber is laid in with a caulking iron, and then hammered in with a caulking mall or mallet and then we'll take the oakum, a coarser fiber, and lay it in on top of it - the same process. And then the final step - you'll see the crew working on it now - is to go ahead and pay in some pitch over the top. And at the end of this you've got a very tight deck system - hopefully waterproof through the rainy season. Knock on wood. And we'll see how it goes and keep you guys updated.


Park Ranger David Pelfrey explains a traditional, wooden ship maintenance task: caulking the deck to make the vessel watertight.


1 minute, 31 seconds


NPS, Lynn Cullivan

Date Created


Copyright and Usage Info