I think the magnitude of vibrations felt on a ship in calm seas probably are an order of magnitude more than a stationary clock. Perhaps that is why it rates a

I think the magnitude of vibrations felt on a ship in calm seas probably are an order of magnitude more than a stationary clock. Perhaps that is why it rates a mention here. While I'm not trying to claim it has no effect, the effect must be slight enough as to be negligible, otherwise we'd have seen some kind of compensation as we see compensation for temperature, spring tension etc. Perhaps I'm underestimating it though and the reason this is not compensated for is simply that these where the atomic clocks of their time. They would represent a significant investment, no idiot would install it in a building set back from a major truck road or expect to be able to run tap dancing classes in the room above. It's quite likely that the manufacturer set out standards for the building it was installed within, perhaps even down to the type of foundations it had to have.