A person whose job is to caulk ships; a skilled worker who seals seams in wooden vessels using oakum and pitch.
From calk (caulk) plus -er suffix (indicating a person who does something); calkers were essential, skilled tradespeople in shipyards.
Calkers were so important to ship maintenance that they formed their own guilds and commanded high wages—they could literally make the difference between a ship that sank and one that survived a voyage.
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