A single-track hydrofoil boat has two upside-down T-shaped hydrofoils that are placed behind each other on the centerline of the hull. To keep a single track hydrofoil boat upright during flight, the vertical front support strut is used as a rudder which the pilot steers into the direction of the fall. This is comparable to how a bicycle maintains lateral stability. A generalized dynamical model for single-track hydrofoil boats was developed to predict the roll and yaw motions under a steer input of the front strut. These motions were approximated analytically with conventional aircraft flight dynamics theory. The derivative coefficients that determine the coupling between state variables were derived from basic design parameters of the single-track hydrofoil boat. Validation of the model was done by experiments with the TU Delft Solar Boat 2016. The steer input, roll rate, yaw rate, roll angle, boat velocity and flight height were measured while the pilot generated a sinusoidal steer input at different frequencies and flight velocities. This data was compared with model predictions in the time and frequency domain. It was found that the model predictions are sufficiently accurate for model validation at steer input frequencies of 1 Hz and less. Therefore, the model can be used to design single-track hydrofoil boats and to simulate the dynamics in nominal flight conditions.