ferry maizuru- hokkaido, room cost?

I want to take the ferry from Maizuru to Otaru, but I can't seem to figure out how much it would cost to get a one-person room. From what I can gather, without a room is 9,000- 10,000, but most websites on the ferry are in japanese, and the reservation center had no English speakers to help. Does anyone know how much a single room is, and how far in advance you have to reserve it?

There are several options (prices differ according to season):

1) S寝台 type bed:
I think it is a bed with curtain rather than a private room. Not available on all ships.
Cost: 14,000 to 19,500 Yen

2) 1等 type room:
A private room with 2 beds, TV and wash basin.
Cost: 16,600 to 24,000 Yen (but might cost more in case of single occupancy)

3) 特等A type room:
A private room with 2 beds, TV, bath and toilet.
Cost: 26,000 to 32,300 Yen (but might cost more in case of single occupancy)

4) Suite Room:
A private room with 2 beds, TV, bath, toilet and refrigerator.
Cost: 46,000 to 48,000 Yen (but might cost more in case of single occupancy)