We did have a wait in the end 3 days, they seem to wait until there is a enough cargo to sail the ferry so I would ignore the posted wed/sat sailing days, it also took nearly 2 days from boarding to arriving in port said. Arrived in the port after calling remon travel each day, then waited all day till 10 pm boarded but didnt sail until 7 the next morning. We were kept well fed though onboard.
We were in no rush but just to let people know to expect a fair wait if they time it wrong. Some other guys here were waiting 8 days just to get on the boat.
Also it really only seems possible to get tickets through remon travel we paid $740 for 2 people + car. Did our own customs and police bit which took an hour max and wasnt to hard. As others have said get into port at the gate marked liman B there are some paper work checks here then park up and get the white transit that flies about it goes south all the way to the other gate, leave the port here then go down the road right then left to blue building 9th floor and get your customs stamp. see gps coordinates above. Back to your car and all the way north past the dubious passenger terminal the far side of the last building is police. All were helpfull some with very good english.
Later the small guy from remon turned up and got a bit arsy saying next time he would do it or something. We didnt get to put our passports in the big cardboard box! But did see it the floor.