Final answer:
V-neck/sleeveless undershirts may not be authorized for daily use aboard ships as they might not meet the regulations or dress code requirements set by the navy or maritime authorities. It is important to consult the specific regulations or guidelines of the navy or maritime organization.
Step-by-step explanation:
V-neck/sleeveless undershirts may not be authorized for daily use aboard ships as they might not meet the regulations or dress code requirements set by the navy or maritime authorities. The preferred nightshirts mentioned in the provided information are made of ordinary rectory cotton and don't have V-necks or are sleeveless. It is important to consult the specific regulations or guidelines of the navy or maritime organization to determine the authorized clothing for daily use aboard ship.