My dissertation project uses the records of British naval courts-martial to reconstruct the body culture aboard the “wooden world” of navy vessels—the culture of the men who built and maintained the British empire. My focus is on the years 1688 to 1783, a period of pivotal military and imperial expansion. I show that the constant production of bodily knowledge was an essential feature of shipboard communities, where sailors monitored each other closely to detect disease, drunkenness, the results of violence, poor medical care and provisioning, and sexual activity. They used the knowledge they generated to help and discipline peers, to pursue their own aims and to attempt to ensure their communities' safety. Historians have come to recognize that knowledge of the human body assumed increasing importance as naval administrators built and managed their expanding force. They have not, however, recognized that sailors themselves produced and used bodily knowledge as they self-regulated in response to the immense difficulties and dangers of their jobs and lives afloat. Usually this knowledge was not set down in writing, but it was recorded when it was articulated before courts-martial. The records of trials allow me to explore the varieties of knowledge sailors generated and to reconstruct the ways in which they used it. By looking at the production and use of bodily knowledge from the bottom up—from the perspective of regular sailors rather than administrators and elites—my research enriches our understanding of the dynamics of these important early modern communities and supplements literatures on a range of topics, from maritime medicine to homosexuality in the navy, that have generally been considered from the perspective of those in authority. Only by attending to shipboard body culture from this bottom-up perspective can we understand the experiences of ordinary seamen during the age of sail, how their communities worked, and how the empire was built.