Martha's Vineyard Museum
A caulking mallet is a tool used in the process of making wooden ships watertight. In order to seal the cracks between the ship's wooden planks, caulkers use a caulking iron and mallet to fill the space with oakum. When the wood and rope get wet, they swell, so no water can leak through the cracks between the planks. Caulking requires a great degree of skill to be done correctly.