Have you ever wanted to learn how to caulk a deck? A traditional skill you might never use yourself but can learn to appreciate!

This will be a brief lesson on how to caulk a deck, for those interested in traditional nautical skills or those who just like learning new things that they most likely will never personally use, but you never know!
We will just be doing some small repairs that go fairly quick
Shown here is a ball of oakum, a tarred plant fiber that is used to pack seams to make them watertight. As well as caulking irons and making irons for adding the oakum to the seams. The caulking mallet is useful in that it is designed to absorb most of the force so it does not get sent into your wrist!
Lastly you will need a deck!

Our deck is on the Kalmar Nyckel, the Tall Ship of Delaware

First thing is to remove the bad pitch, the black sealing 'tar' you see between planks
Reefing irons and reefing hooks are used here along with a more basic mallet
Obey the chalk marks to know where to work

The goal is to remove any old, cracked, and overall bad pitch. We can see when it is cracked and brittle looking or can trace leaks belowdecks back to where the problem is on deck.
Poor watertightness leads to rotten oakum or cotton as they get wet, which leads to more rot issues and eventually leads to a very bad day, best to catch it early!

You can see the poor condition of the pitch here especially, it ideally should be smooth and flat, not dry, cracked, and domed.
When using a reefing iron like a plow to lift out the pitch, usually the first layer of oakum in the seam comes out as well.
The space between planks is not a straight, parallel slot, but a tapered wedge that nearly connects at the bottom and gets to 1/4 inch to a half inch wide at the top depending on the seam and its location.
As pitch and oakum is pulled up, it is inspected. If it is wet or powdery, it is bad, it should have long, strong fibers and smell slightly of pine tar.

Most of what we were working on was good oakum with good cotton below, so only the top layer of oakum to be replaced as it was pulled out with the bad pitch
The oakum is pressed in in small loops, basically from as shown here then into the seam

The result is several tightly stacked loops, if we were doing deeper seams we would pack more oakum in, since these are fairly shallow as they still have a layer of cotton at bottom and 2-3 layers of oakum already, we don't need to put too much in
The thin caulking iron here is used to bring oakum into the seam by hand

Then we use the thin caulking iron and wider ones to tuck down stray hairs on the edges, then cris-cross slightly in the seam to harden/make the oakum in the seam
Making irons sometimes have a groove cut the length of the face to help catch stray hairs
Hand set oakum on the left, 'tucked oakum in the center, and made oakum on the right of this seam
We use a caulking mallet (first pic) to do this, less wrist injury chance, and wood to metal is less tool damage

Butt joints get a zig-zag of oakum, this gets made then a squiggle crossing the opposite way
This makes the oakum stay better and the seal better

Fully made seam!
About as deep as it is wide, no stray hairs, ready to add pitch!

Tape around the seams to be poured makes for much easier finishing

Pitch is sold in 25 lb to 100lb bricks, poured into cardboard boxes usually
We chisel off chunks and heat them up carefully, it can never be allowed to boil otherwise it becomes brittle when cooled
We want the pitch to remain somewhat soft so it moves with the deck, as the boat sails the boards shift and rub, on hot days the pitch softens and reseals back to the seam/deck a bit

We had 2 people caulking with a third coming in to help tape and heat and pour pitch, we got about 60 linear feet of deck caulking done in one day

These were all nice long and straight seams with no obstructions, we have several curved seams, ones near bits and vertical obstacles, and super inaccessible ones as well

One more day of using a heat gun and flat scraper to remove excess pitch and flatten the seams flush with the deck

3 people, 2 days, only 60 ft of deck seams completed
We try to do about 30-45 days of deck caulking each year usually with 5-10 people at a time, the ship is about 100 ft long on deck and like 30 ft wide, each seams is about 6in apart, about 1/6 gets done each year, and that is not even mentioning the outside of the hull which is done the same way...

Therefore we play with puppies!
Way less work!