This study examines sea loans in the Portuguese Empire (1600–1800). Structured as contingent contracts, this kind of credit served as a risk-sharing agreement for financing transoceanic trade routes. Using notarial protocols and court records, the study examines how maritime regulations, international political relations, and information problems influenced the pricing of loan agreements. The study demonstrates that the introduction of the convoy system, which distinguished Portugal–Brazilian connections, coincided with a downward trend in sea loan rates, which converged with those of safer short-term lending instruments. In contrast, periods of war and free navigation increased uncertainty, making maritime insurance and sea loans complementary instruments for risk management.