Our original fixtures have festoon bulbs and made finding LED bulbs that fit a bit tricky. We finally found some high power LED festoon bulbs that came in warm white (not that cold blue white) from SuperBrightLEDs.
Why? Well, our original fixtures took about 1.2 Amps (12 VDC) per hour and these take .1 for the 2 x 3 LED light fixtures and .2 for the 2 x 6 LED light fixtures. I can now run the brightest lights in the house for 6 hours for the power it took to run the old ones for 1 hour.
We were indecisive for a long time because we don't use lights that much, for that long now and so although the proportional saving is great, we calculated that if we use two lights for 2-3 hours (more than we usually do because we like our oil lamp - but that comes with its own cost, hauling fuel for it) we were only saving 3 Amp hours per day total.
We bought the 3 and 6 LED versions and tested them out. After being indecisive and then forgetting about it for about 6 months, we finally bought enough to change out all 11 original fixtures in the boat. We put 2 x 3 LED bulbs in 9 of them and 2 x 6 LED bulbs in two areas - over the kitchen and over half of the salon table near the kitchen.
What ultimately put us over the edge was the emotional component. In the dead of the winter up here when we get so little sun, we can light up a bunch of lights without stressing. That, right there, made the decision for us. It is a small amount of money compared to what you spend on boat stuff for a significant change in our style of living - DONE.
I don't have any way of testing but I believe that the 2 x 6 LED lights approximate the light from the original bulbs in strength with a slightly flatter, more shadowy flavor.