Commercial fishing boats can be out on the water for as many as ninety days at a time. There are few cases where such a boat has to stay out for the entirety of a fishing season. To make it possible for these models to withstand the roughness and abuse of saltwater, they have to undergo an inspection before leaving the harbor.
Such an inspection is usually programmed and takes place every several months or so or at a given point in time defined by the construction of the boat and the purpose it is used for.