Crew cabins are the the two small single cabins in the bow of the catamaran.
They are fine for sleeping, but that's all you can do. They have acces from the deck through the window. Normally there is a side window as well for extra light and ventilation. You share one of the bathrooms with toilet and shower inside the catamaran and of course there is always an outside shower as well.
Most of the crew cabins have one or two small lockers and more storage under your bed. If you need more storage, we can always find some more space on board. They are basic spots. Good thing is, as a single, you don't need to share a cabin with split double bed or double bed with a stranger, and the crew cabins are 30% cheaper.