The question is related to work in Norwegian waters on a foreign flagged vessel.
How long can a person remain on a ship that is doing oilfield related work? For example a pipelaying vessel or a barge.
What is the maximum period of time a person involved in laying the pipe (e.g. welder) can stay on board?
How long a time period off is the person to have before coming to work on the vessel again?
The ships listed by you are considered to be vessels in the legal/regulatory sense of the word, cf. the regulations relating to health, environment and safety in the petroleum activities (the framework regulations) section 4 on application of the working environment act in offshore petroleum activities etc.
This means that the people on board come under the rules of the country in which the vessel is registered, cf. the flag state principle. Hence, Norwegian requirements to maximum periods of stay and time off do not apply.