The advent of autonomous systems has been regarded as transformative across various industries. In the maritime domain, these technologies seem especially promising, as they are offering significant potential to expand operational reach and address impending personnel shortages. Still under development, the Large Modifiable Underwater Mothership (MUM) represents a unique innovation in this field. Whilst autonomous maritime systems like the MUM hold great promise, their successful implementation depends not only on technical and legal feasibility but also crucially on operator acceptance. Without a thorough understanding of the factors driving or hindering operator acceptance, even advanced technologies risk limited adoption. Although research on user acceptance of various technologies exists, there is a shortcoming regarding the specific intricacies of autonomous maritime systems (AMS) such as the MUM. This conceptual article explores the factors influencing operator acceptance to identify the requirements for successful implementation. Drawing on qualitative interviews with potential operators, it proposes an adapted Technology Acceptance Model (TAM) tailored specifically to the MUM.