The SAIL Data Management Plan is a document detailing the management of all data from Project SAIL - Space-Atmosphere-Ocean Interactions in the marine boundary Layer. Project SAIL aims to improve the scientific understanding of the marine boundary layer by means of a unique monitoring campaign on board the iconic Portuguese tall ship NRP Sagres. The campaign will enable the measurement of the atmospheric electric field over the ocean, and also to study space-driven interactions via the detailed monitoring of GNSS signals, cosmic radiation, environmental radioactivity and atmospheric ionisation. The atmospheric measurements will be complemented by the collection of fish samples and by underwater monitoring of the ocean state (temperature, conductivity, dissolved oxygen, pH, spectral radiance), providing unique data for the detailed study of ocean-atmosphere fluxes and surface-atmosphere interactions.