Dive Planning with a Stinger

I'm fairly new to diving but bought a Stinger to go with my PADI AOW. However I've a question about dive planning. The stinger is great at telling you how long you will be able to remain at any depth, and takes into account previous dives. However it calculates NC times based on you diving at the time you plan. i.e. you can't seems to ask the question "how long can stay at 20m if I start diving in one hours time?

This seems a fairly straghtforward question isn't it?

Is there any alturnative to the good old dive tables and wheels?

regards

The Vytec will allow you to add surface interval to its planning; the Stinger doesn't. The charts or deco software are better to use, because you use your own brain and will learn from it.