Navigation lights help to work out where the oncoming boat is even if they switch off the tunnel light which is a tad daft. Lights aimed slightly off centre to the right, either up to the roof or down into the water helps to prevent blinding oncoming steerers.
Still, when you get those who come to a dead stop and get drawn into you, or even worse, use the bow thruster to keep to their side pushing you firmly to yours, all part of life's rich tapestry inside a tunnel.
But I don't get Francis searchlights - by definition - why??