Per Lord Sterndale MR in The Dimitrios Rallias (1922) 13 Ll L Rep 363, CA at p.365:
The first thing is that there must be a latent defect. We have been told there is no definition of a latent defect, and I am afraid that state of things will not be altered by this decision. I do not propose to give a definition of latent defect. But I think, at any rate, it is safe to say that if a defect such as appeared could be discovered by the exercise of ordinary care, it cannot be said to be latent. I do not mean to say that is a complete test. I think the Judge has treated the case rather as if the question of whether a defect was or was not latent is the same thing as whether the person charged with the care of the vessel was or was not negligent in not discovering it. I am by no means convinced it is the same. At any rate, I am not going to define latent defect any further than I have done.