Have you recently taken the boat from Sassnitz in Germany to Klaipeda in Lithuania?
I check the following url http://www.dfdsseaways.de/ and it seems that the boat departs at 9pm and arrives the following day at 4pm. This seems to be a very long boat trip for a short duration.
Can you comment on the trip if you have done it recently?
18 hrs for 600 km (33 km/hr) is a normal speed for a ferry. DFDS boats are not superfast ferries.
quote: This seems to be a very long boat trip for a short duration. do you mean: 'relatively short distance'?
the ferries on this route are geared almost exclusively towards the transport of trailor trucks and goods - to employ superfast catamarans or similar for this wouldn't pay off.
I'd say that in terms of time & money, personally I'd rather search fur a budget flight with ryanair or airbaltic.