A set of algorithms was developed in the CAL3D occupant simulation program to allow belt sliding in a direction perpendicular to the beltline. Such algorithms were used to construct a belt-restrained occupant model that would predict the occurrence of submarining. The lower torso of the previously developed Hybrid III dummy model was improved for more detailed description of the geometry and assessment of abdominal compression due to submarining. The simulation results compared favorably with two sled tests having two different seat angles; one resulted in occupant submarining, one did not. The model was then used to examine a number of design parameters which may influence the occupant submarining tendency. The most dominant design parameters for the vehicle investigated in this study appear to be the the seat back angle (which determines the occupant upper torso angle), and the lap belt angle. A diagram for these two important angles was generated to indicate the submarining and the non-submarining regions.