I swapped in LED bulbs and replaced the masthead light and deck light fixtures.
Keep in mind that cheap chinese amazon led bulbs are crap. They are often factory seconds. I would rather pay more and not have to touch the nav lights for years.
(I used amazon led lamps for the cabin fixtures, but am reconsidering that)
Odds are your boat used Aqua Signal series 25 fixtures. Replacing with the same fixture but with LED bulbs makes it easy.
LEDS are not full spectrum. So a "white" led doesnt work with the bi colour lens on the bow. That is why Hella, and Aqua Signal make bulbs that are half red half green, which need to be aligned correctly.
Switching to interior and exterior LEDs was a great upgrade. The lights are brighter and we use very little power compared to the original incandescent ones.
I bought my stuff from doctorled.com, who specialize in marine LED fixtures and bulbs. Ofren made in the usa. Some they sell are actually certified to the 2NM standard
LED retrofits are becoming common.
Sailboatowners.com have aqua signal fixtures as usual but they also have led bulbs. Including the dr led brand.
Dr LED Nav Bulb - for Aqua Signal Ser. 25 Bi-Color Light
shop.catalinaowners.com
catalinadirect has been mentioned... They sell a complete kit if you are inclined that way.
Some have also mentioned marinebeam in the past but have never looked into them.