Older marine dome light (boat interior lights) use a lot of power on a boat, typically drawing about 1A to 2A for a 20 watt bulb. While not the biggest power hog on marine, Would be quick and easy switching them over to LED marine lights for boats. Very bright LED marine lights for boats would draw only 20% current than older narine dome light bulb.
You can got all kind replacement bulbs from ledlightbulb.net. They have replacement bulbs for virtually every light fixture. Just removing the old bulb to see exactly what type it was — both what type of base and the wattage.
LED marine lights for boats, P28S LED light bulbs. Marine lamp Navigation Signal Lamp, P28S LED Filament Bulb.