]One of the reasons why recreational computers can't be used for staged decompression diving is that they don't behave like real deco algorithms. [/B] I have read stories of dive computers racking up ridiculous amounts of deco when the diver didn't immediately march to the stop depth and stay there. Some of the computers do not give you any credit for offgassing below the mandatory (shallow) stop depth. Others will do as described, and clear as you ascend. Unless you are quite knowledgeable about the behavior of your own computer, it's unwise to dawdle when you are showing a ceiling. People without decompression training won't know if the 60 minutes of mandatory deco their computer is now showing is reasonable, or whether it's the product of a device that was never designed to do what you are doing with it.
My husband did a dive at the Catalina Dive Park years ago, using his Suunto computer in computer mode. It was the second dive of the day. There were six of us diving together. Of the six, only Peter incurred any deco (even though we had all dived very close together, and Peter and his buddy did EXACTLY the same profile). By the time we got to the stop depth, his computer was showing TWENTY MINUTES of decompression, and nobody else had any. Luckily, he had the gas to sit and wait it out, and he did, because he wanted to use the gauge for the next dive and so he had to make it happy. He knew darned well, as did we all, that he didn't really owe a twenty minute deco obligation. But if you don't have the training and this is what your computer is saying to you, and you realize you don't have the gas to do the time, you are in a world of hurt.