The design of a submerged nozzle or the conversion of an external nozzle into a submerged one is a common solution for optimal space utilization in motors facing volume or length constraints. In a submerged nozzle configuration, the nozzle's inlet duct, throat, and a portion of the exit duct can be recessed inside the combustion chamber. Designing a submerged nozzle is more complex than an external nozzle because, structurally, the submerged section must withstand not only the forces on the internal surfaces but also the external pressure force. For this reason, there is also a possibility of increased engine weight due to the use of a submerged nozzle. This paper focuses on the conceptual design of a submerged nozzle with the aim of converting the external nozzle of a specified engine into a submerged one. Five designs based on submersion ratios from 15% to 75% were selected, and for each, a table of longitudinal, weight, and internal ballistics estimates was extracted for two states: a fixed body and a body with extended length. Evaluation of these designs shows that submersion ratios of 60% and 75% cause a significant loss in total impulse, which requires an increase in engine length in the grain and body sections to compensate. The optimal design is achievable in the 30% to 45% submersion ratio range since it results in a suitable length reduction, and the associated weight increase and total impulse loss are minimal.