This paper provides evidence that instances of collocations and idioms in English and Spanish discourse are not simply dead metaphors but retain much of their metaphorical and pragmatic value. Twenty-five samples from authentic texts will be provided, discussing the problems involved and the solutions put forward by 20 practising translators when they translate metaphorical and metonymic language from naval engineering and technological texts, both written and spoken. These metaphorical collocations and idioms tend to appear neatly encapsulated in English and sometimes cannot be rendered metaphorically into Spanish (i.e. fighting for -air>la falta de aire; lead to symptoms> gaparición de estos síntomas in a text about engines or metaphors related to naval engineering such as: slamming> hundimiento de carena). These examples reflect how the two languages share fairly similar conceptual metaphors in relation to the subject sea, which are not only found in the maritime genre but also in everyday language texts to add emphasis. The paper ends discussing some of the didactic implications of using metaphorical multiword units (MWUs) for learning terminology and technical translation.