This is our tiny floating home when viewed from another sailboats mast. I have lived here since 2012, my fiancee has been living here since 2014.
The overall dimensions are 45 feet long, 11 feet wide, but as you can see, it is only 11 feet wide at one point. Most of the boat is much narrower than 11 feet, but we maximize all the space available.
The actual living space is much smaller than 45 feet though. The back half is almost entirely storage lockers. Forward of the bed is storage for the anchor chain.
The thin area with no label is the only space available for walking, everything else is consumed in seating, sleeping, or storage areas. To add additional storage space, all the floors can be picked up to reveal even more storage space.
We store water bottles under the floor on long trips because it keeps the weight low in the boat and we don't have to get to them that often. I usually pull up the days ration for drinking water in the morning and then close the floors up again.
While it might not look like much space available, the limited amount of space is used very efficiently. Every area serves multiple purposes, it's usually a combination of storage, sleeping, sitting, or working area.