Timely and accurate fault diagnosis of ship oil purifiers is essential for maintaining the operational reliability of a degree-4 maritime autonomous surface ship (MASS). Conventional approaches rely on manual feature engineering or simple machine learning classifiers, limiting their robustness in dynamic maritime environments. This study proposes an adaptive latent space learning framework that couples a two-dimensional convolutional autoencoder (2D-CAE) with a component-aware triplet-loss regularizer. The loss term structures the latent space to reflect both the fault severity progression and component-specific distinctions, enabling severity-proportional distances among a latent vector learned directly from vibration signals even in a limited data environment. Using data collected on a dedicated ship oil purifier test bed, the method yields a latent vector that encodes the fault severity and physical provenance, enhancing the interpretability and diagnostic accuracy. Experiments demonstrate enhanced performance over state-of-the-art deep models, while offering clear insight into fault evolution and inter-component dependencies. The framework thus advances intelligent, condition-based maintenance for autonomous maritime systems.