I know people do it all the time, but it is generally a bad idea to install LEDs into red and green navigation light fixtures designed for incandescent bulbs, like the Aqua Signal Series 40.

LEDs retrofitted into these fixtures typically do not give the designed brightness with the colored lenses.  "White" LEDs are not truly broad spectrum white light, but actually produce a series of narrow cut frequencies that, when averaged together by our eyes, appear to be white.  The problem is that these bands do not necessarily line up well with the colored lenses that are used to filter the light from an incandescent bulb, so less light, sometimes a LOT less, gets out of the lens than would be true with an incandescent bulb of the same nominal brightness.

You will rarely get the hoped for designed life out of an LED retrofitted into a fixture that is not hermetically sealed.  Lastly, there is the issue of VHF radio interference that is frequently poorly controlled with retrofit bulbs.

If you want to go to LED bulbs, and that is certainly a very good idea for a lot of reasons, it is far better to switch to a fixture designed for them.

Bill Kinney
SM160, Harmonie
Charleston, SC, USA