"I had my skis sharpened at the end of last season...they should be good, right?"
Nope. It is time to do one of two things: sharpen them or get them sharpened.
With this bi-polar winter's combination of absolutely wonderful new snow, warm day soft snow, and re-frozen extremely hard snow, one day your skis can feel fantastic and the next day they can't hold at all. Remember, as soon as the temperature drops below 32 degrees, you are going to be skiing the hard stuff at some point during the day.
So, what is the life span of sharp edges? It all depends on the conditions. A full day of hard skiing on boiler plate — hard ice — will dull your edges. Yes, a single day. When the ice is soft (yes, there is soft ice and hard ice), you might get a few days out of your sharp edges before they completely lose their sharpness.
Ideally, you should get your skis done at your favorite ski shop, and then buy a side-edge bevel tool and a diamond stone or the correct files (they can help you with this purchase). After a hard snow day, touch up your side edges and keep them sharp.
The racers always keep track of their practice edges and their race edges. They write R and P on their skis with little arrows pointing to one side(P) or the other(R), and they stay off their race edges until race time. This way they know they'll have sharp edges for race runs. This is a good idea even if you don't race. Ski one set of edges regularly, and save the other edges for the next icy day.
Remember, best advice of all, take a lesson or attend a race clinic. You'll have a great time and improve your time.
John Macdonald is a Level III Certified PSIA Instructor and is a Race Team Coach at King Pine Ski Area. You can email questions to John at firstname.lastname@example.org.