As used in this section, the term “civilian nautical school” means any school operated and conducted in the United States (except the Academy maintained under section
1295b of this Appendix, any State maritime academy assisted under section
1295c of this Appendix, and any other school operated by the United States or any agency of the United States) which offers instruction to individuals quartered on board any vessel for the primary purpose of training them for service in the merchant marine.