The larger, but very similar boat house at
Boldt Castle in the Thousand Islands had flooring sections that could be
"lowered" into the water, allowing smaller boats to be floated inside..as one would expect..then the entire floor would be raised by a number of mechanical jacks.
I remember seeing the heavy screw jacks, but can't remember if they were driven by electric motors or not. The boat house would have had to have a steam plant to provide electricity...which would not be out of the question given the money available.
The idea was to be able to raise the floor, providing space for large social functions near the water.
NB
Boldt Yacht House:
http://en.wikipedia.org/wiki/George_...dt_Yacht_House