As you probably know, there was a secondary meaning for "Blue Lights"...
It is the source of great joy to my soul to be able to state, that in the present day we can boast of a few captains who are holy leaders and commanders to the people; and though they are stigmatised with opprobrious epithets, such as Blue Lights, Psalm Singer, Saints, &c* they are not ashamed of the gospel of God. While they serve an earthly king, they are concerned to be found amongst the small number, who serve the King of kings, and Lord of lords.
*These are the usual expressions which sailors use when talking of religious characters on board ships.
from:
The Christian mariner's journal; or, A series of observations and reflections on a ship; the sea; sailors; the works of God; the heathen; war; time; death, &c. &c. intended for the benefit of seamen, and the general good of every person. Written at sea, by an officer in the Royal Navy. London, 1829
An ambitious work indeed!
Looks like there's a new book about the so-called Blue Lights:
Evangelicals in the Royal Navy, 1775-1815: Blue Lights and Psalm-singers
by Richard Blake
Boydell & Brewer, 2008
Publisher's blurb:
The Evangelical Admiral Gambier, notorious for distributing tracts to his fleet in a theatre of war, is commonly seen as a misfit in a fighting service that had scant time for fervent piety. In fact, the navy of the Revolutionary and Napoleonic Wars showed a level of religious observance not seen since the days of Queen Anne. Evangelical laymen provided one dynamic for this change: concentrating first on public worship, they moved to active proselytism in search of converts amongst sailors, and in a third phase developed a loose network of prayer groups in scores of ships, uniting officers and seamen in voluntary gatherings that transcended rank. This book explores the effect this new piety had on discipline and human governance, on literacy, on the development of chaplains' ministry and on the mindset of the officer corps. It also looks at the larger question of how its values were absorbed into the ethos of the navy as a whole. It draws on sources both familiar and unusual - logs, letters, minutes, memoirs, tracts and sermons, Regulations - to explain how evangelical influence affected officer corps, lower deck and Admiralty, showing how a movement that began by promoting public worship at sea became an agency for mass evangelism through literature, preaching and off-duty gatherings, where officers and men met for shared Bible reading and prayer a mere decade after the great Mutinies.