Do I need to leave Thailand and re-enter right before joining a ship as a crew member on a visa exempt status?

A Norwegian individual entering Thailand on a visa exemption for 17 days before joining a ship is concerned whether they need to leave and re-enter Thailand before boarding. Comments suggest that typically crew members are stamped out upon boarding the vessel and stamped in again upon returning to shore. As a visa-exempt traveler, they can stay for up to 30 days and can extend their stay if necessary. It seems unnecessary to exit Thailand before joining the ship, provided they ensure they receive the proper exit stamp before departure.