norwegian national insurance contributions

yes !!
you should have received from your company a certificate for exemption to Norwegian social insurance.
claim for 10 percent standard deduction class allowance and Seafarers Allowance (130 days on vessel), on top of your standard allowance.

from taxnorway.no

The following are deemed not to be ships in service:

Ferries or passenger vessels that only sail between Norwegian ports where the distance between the first and last port of call is less than 300 nautical miles.
Vessels used in petroleum activities that are engaged in exploration, exploration drilling, extraction, exploitation and pipeline transportation.
Ships that sail on Norwegian lakes and rivers.
Ships engaged in stationary activity and harbour traffic or other activity over a limited distance where the distance sailed does not exceed 30 nautical miles.
Accommodation ships or ships used as work platforms, missionary ships, theatre ships etc.
Pleasure craft, vessels used for hospitality purposes, shuttle boats etc.
Fishing, whaling and sealing vessels, but only for the period the vessel is used for fishing and whaling/sealing.
The rule requiring 130 days on board during the income year:

In addition to the main occupation requirement, it is, in principle, a requirement that the seafarer has actually worked on board for a total of 130 days in one and the same income year. Days spent on board the ship where the income is not subject to Norwegian taxation can also be included when calculating the 130 days.
If the seafarer has worked on board for less than 130 days, the condition is deemed to be met if the employment relationship is covered by a collective agreement that presupposes at least 130 days on average on board during the year.
If the seafarer has started working late or finished working early in the year, so that he/she has less than 130 days on board, he/she may nonetheless qualify for the seafarers’ allowance if the employment relationship is covered by a collective agreement as mentioned above.
If the seafarer has been ill and has received sickness benefit for part of the year so that he/she has less than 130 days on board, he/she may nonetheless qualify for the seafarers’ allowance if the employment relationship is covered by a collective agreement as mentioned above.
Work for short periods of time on board (less than 130 days) as a stand-in or similar do not entitle to seafarers’ allowance even if the employment relationship is covered by a collective agreement.