Greetings,
Mr. GB. The majority of interior lighting aboard our Cheoy Lee 46 LRC is/was fluorescent tubes. The following may not apply to you:
I have replaced a number of the fluorescents and their associated ballasts with LED strips. https://www.apollolighting.com/mega-led-strip-warm-white-360-lumens/
Cut strip to length. Slide on connector. Peel and stick strip to fixture. Connect 12V. Walla! Not quite "plug and play" like bulbs but pretty simple.
There are several threads dealing with sources for LED equipment on the internet. We shopped, in store, at https://www.apollolighting.com/ , in Fort Lauderdale. We probably paid a premium price but the store was close by.
Good afternoon, I checked your profile for any clues as to your vessel details. No luck. I think you are in the UK although you have Alabama as your state.
Would be a good idea to fill out the profile info to get more focused replies. If you can figure out how to upload photos (its a process ) That will help.
There are many many different LED fixtures that were designed to plug in to old Incandescent sockets.
Most of ours have been in fixtures that use replaceable G4 bi-pin bulbs... so we replaced the bulbs with G4 bi-pin LEDs. Usually discs with 9, 10, or 12 LEDs, 10-30V, warm white from marinebeam.com.
We've also had some courtesy light fixtures that took wedge bulbs, usually T10s. Ditto from marinebeam.