create unknown long fade time + 10 mins

[steen4sun]

Hi
Doing a titanic party.
Got 20 LED par uplight
of course we will get hit by iceberg, and then the "ship" will be filled with water.
How do I show that using the uplights ?
well, I dont know how long it will take, my idea is to create say 10 switches, each with more blue than the previous one.
then shift between these, and the ship is "sinking" ...
As a detail deep green could be the beginning, the movie has got a lot of green in that period.
but, how would *you* create this effect ?
demands :
easy manual control
long fade time + 10 mins
some kind of automisation could be nice ...

TIA
Steen

[simonB]

If the time could change between shows, I would create several switches with fade times and then put them into a cycle called 'Sinking'