"Lane lines" pass also from Santorini to Sitia every Tuesday and Saturday, the arrival time in Santorini is 04:00 and the dep. time to Sitia is 04:30. The price is around 20 euro, and the duration of the trip almost 6:30 hours.
Please always ask in the local travel agencies to confirm hours and time tables.
I've learnt my lesson... next time if I can fly from Santorini to Crete, I would do so. Unfortunately on the day of departure, there was no flights or high speed ferries. So had to take the slow boat which took forever to get to Crete.
Finally arrived at 10pm In Heraklion and had to drive to Hania where I was staying which took another 1.5 hours. Very difficult and dark to drive at night as most roads are not lighted. Not a very pleasant journey.
The easiest way to get between Hora Sfakion/Loutro/Agia Roumeli/Souyia and Palehora is to catch the small coastal ferry. I am reliably informed that this is nicknamed the podoufla (flip-flop (thongs in America)).
Note that heading from Hora Sfakion there is a stopover in Ayia Roumeli, with the boat to Souyia/Paleohora not leaving until about 1645. Watching the hot hordes emerging from the gorge is entertaining though - especially when you're sat with a very cold beer!!
We chose for a trip to Santorini, which turned out very luxury... Worth to treat yourself once a life...