Conserving energy is a way to help cut carbon emissions and save money but on a boat it takes on an overriding importance; and that is because energy is finite. You are either bringing it with you, stored in the form of Diesel Fuel to be converted, or harvesting energy from the Sun and Wind as you may.

Alternative Energy will be pursued but at this moment part of the big picture is to reduce reliance upon it by not wasting. Observe that the boat has a dozen or more light bulb consumers. These are 12v single filament bayonet mount style which are relatively cheap and serve well but at they are hungry. The old school bulb on the left squanders 15 watts. The new solution pictured right is an LED using only 1.5 watts for an equivalent light output.  There are even red LEDs (vision preserving for night ops) and .8 watts with reduced lumens.

More minutia: It only took the better part of a day to properly source this retro-fit. There are quite a few styles, sizes, and types from which to select. The Sea Dog dome lights utilize a double contact base for + and – not to be confused with the automotive setup which uses the base itself for a negative ground and the double contacts for dual filaments. The challenge was to procure a globe that fit the lense fixture and a socket that fit into the ba15d base as designed.

It all adds up, but this small effort will reduce the need for additional capacity. I suppose this brass wick oil lamp might be the outstanding supreme fix.