Bob,
Before bothering to empty the water out I'd try to find out how it got in.
Just hold the mast under water and see where the bubbles are coming from.
Once I knew that I'd select the better option to get it out. eg- As Robi said-
If it is coming in the top plug you could empty when you take plug out to reseal etc.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!