Warships laid up in ordinary did not retain full crews, so the state needed experienced people already working at sea when ships were recommissioned. The merchant marine supplied sailors, topmen, riggers, and sailing masters for that emergency pool. Legal preference for English crews therefore had a manpower purpose alongside its commercial advantage. It used private profit to maintain skills and infrastructure that the government would otherwise have had to fund continuously, while customs income helped support the expensive peacetime navy.
Notable Point · 30:20-33:38
Merchant seamen as the Navy's reserve
Crew nationality rules maintained a pool of experienced sailors and masters who could be mobilised for wartime naval service.