Dimension is shipyards that open a few months and close for a few. Question on how to model?

Hi,
Our business is a few shipyards where ships arrive, unload material and then leave. A shipyard is open for business for some months, then shuts down for maintenance, then reopens and so on. We are trying to calculate shipyard utilization (i.e. total ship time in shipyard, divided by total Shipyard Open time).

My dimension is Shipyards, which has Shipyard name, Shipyard number. How do we add the particular Shipyard Open Date and Close Date in this dimension? (NOTE: The shipyard is open for several weeks or months at a time, and then closes for several weeks).

Thanks in advance!

Opening and closing a yard is a business event, wither it is opened or closed is a business state. One or the other should be maintained in fact tables. You may carry current status on the dimension, but it doesn't seem it would be useful for anything.