Origin of royal mast
Examples from the Web for royal mast
Above the topmast comes the top-gallant-mast, and above that the royal-mast.
At that moment we would rather have seen the royal-mast of the Pandora than the largest herd of antelopes in the world.
The top-mast, topgallant-mast, and royal-mast; any spars above these are termed poles.The Sailor's Word-Book|William Henry Smyth
The royal-mast still towered above, and below, threatened the dark face of Le Gros.