My wife and I have been on many cruise ships and every one of them has preheat fluorescent lamps not only CFL's but all the linears too. I've haven't seen a instant or rapid start lamp as of yet. Does anyone know why this is?

Isn't there 230V (220..240V) installation for the lighting?
On 230V the preheat is the simplest ballast: Just a series choke and a starter.
On 120V, when you need a step up transformer anyway, the RS mean just two small windings extra compare to the preheat, what is cheaper than the starter.
But on 230V the RS would need either two windings on the ballast (to get a SRS form) or a separate transformer, while both is way more complex than the simple starter.
And the preheat can easily operate even the more efficient T8 lamps (on a ship the electricity is many times more expensive than on the shore and most ships are not that old, so were designed when the more efficient T8 were already widely available, so really utilizing the extra efficacy).
I would not be surprised, if the 230V for lighting would be used just to be able to use the more efficient simple series choke ballasts.

And electronic (the only IS with reasonable efficiency) ballasts are not as widely used, because they may disturb the navigation and communication equipment (terrestrial navigation is operating at LW, communication at SW, both very susceptible to the disturbances from devices like electronic ballasts). Moreover you may make the magnetic ballasts more robust against salty water in an easier way than the electronic.

A number of ships appear to have proprietary power systems, like 440 V at 60 Hz or 690 V etc. This obviously calls for special lighting installations, which probably involve special luminaires for straight operation from the ship grid. This would explain why they are all preheat: They're no standard 230 V gear.

Maybe for distribution, but for the lighting they mostly use the same system as used on the land, usually according to where the ship was build.
The main reason is the ability to use generally available components as much as possible.
There is no point on using some special voltage for lighting and cabin installation, it would mean all the equipment being unnecessarily too expensive (not only lamps, but as well switches, circuit protection,...)

Of course, the "backbone" network may use some rather special voltage, but that is then transformed to the usual voltage locally for given area.

And small vessels are frequently equipped with just a DC system (24V or even 12V)...

That, as well as providing power outlets in the cabins for passengers and crew to use


BG