Stack timer question (rebreather use)

[doctormike]

Indeed, it is a simple reminder, but we have grown to trust our 'magic bracelets'. I don't think it's meant to replace common sense and reason when it comes to scrubber time. The good thing; a warning at -1hr and alarm -30min, even if it's not factual, will drive the point home better than just a mental reminder. "...I've set up this timer, am I going to ignore it now?"

Yup, I like it too, and use it. The same way I like a physical printed checklist. It's easy to get distracted and forget stack time, this is a good thing.

I was just making the point that you need to understand what it really represents - there was some suggesting early in the thread that a few minutes added or subtracted from the stack time was a precise thing that needed to be accounted for so that you would get exactly the right amount of time that you were owed from the scrubber. I don't think that is really how it works...

 

[rjack321]

I would hope that whatever time you tell the stacktime counter isn't so close to the edge that it matters if your turn on and/or prebreathe time was 2 mins or 15 mins. If I could implement stack time on my own wrist, I would have it turn on at 1 or 2ft depth. I could see why they might not choose that start for widespread implementation however. And I also somehow managed to survive without a stack timer at all so there's that.

 

[rddvet]

Why would I want to cheat a computer. If a simple change can improve the accuracy, why not ask for it?

I'm already cutting the stack timer short by 30 minutes. But I would like to keep more accurate data on the scrubber. How much time I actually have used it since dive time doesn't count all of it.

Shearwater, thanks for looking into it.

You're creating a problem where a problem doesn't exist. If it's that big a deal to you, then shorten your stack time by 15 minutes. Should you realistically rely on the stack time to be your go/no-go decision maker, and in the grand scheme of things does 15 mins of surface breathing mean a CO2 hit? Probably not. My scrubber gives me about 6 hours of dive time. That's about, because there's not solid evidence that it will always last 6 hours, just assumptions based on experience and the experience of others. To be safe, I set my stack time to 5.5 hours.

15 minutes should not make a big difference. Shearwater should leave it how it is. Not too many others have an issue with it.