Currently, pilots maximise the performance of Seaglider underwater gliders by manually selecting their set-up parameters. Building on existing procedures based on the assumption of steady-state motions, a recommender system for the trim and flight parameters has been developed to aid trainee pilots and enable round-the-clock operations. The system has been validated with data from 12 missions run in waters off the United Kingdom and Australia, representative of a range of oceanographic conditions. The recommended trim parameters present a maximum difference of 14% from the values selected by the pilots, whereas pilots are found not to change the flight parameters. Additionally, suggestions are made to improve operational practices to further improve the accuracy of the recommender system. As a result, the developed system is expected to greatly help trainee pilots achieve expertise in a much smaller time frame than standard practice. Additionally, thanks to its high precision, the recommender system can be used to autonomously select the trim and flight parameters of Seagliders for night operations in the future.