so if there is a fault that renders the boat unseaworthy but which you didn't or shouldn't reasonably have known about (say, a hairline crack in a newish seacock fitted by a reputable yard) then the contract wording prima facie allows insurer to argue you are not covered.
That would be what most would consider a "latent fault" I guess?
My own claim that was covered by Denovo was under their latent fault clause.
The definition or policy wording isn't available to me right now - namely as the boat was sold some time ago, but in essence it is a fault that is a manufacturing defect that you couldn't possibly have known about or discovered through your usual maintenance.
In my case, a main bearing bolt had worked loose and was resting on the bottom of the sump. The now very slight looseness around the crankshaft caused metal fatigued which eventually showed itself when the prop was jammed by an unseen underwater solid object hitting it and locking it up at cruising revs whilst offshore. Ping (or rather BANG) the crankshaft snapped.
It was only through investigation that the engineers and insurance companies surveyor discovered the cause of the failure and at that point Denovo guided me to claim under their latent fault clause.
JFMs analogy, would I think, be remarkably similar?