MichaelBaranows:
I am not really sure how to ask this question.
When is a 15' safety stop needed? After diving how deep and long. If I drop down to 30'-40' to tie off boat to I need to stop at 15' for 3 minutes. I know there is another post about considering it a dive but that doesn't matter to me cause I computer can figure out my deco.
Michael, I have a couple issues with your question...
1. Generally speaking, you should end each dive with a safety stop. Make it a habit and chances are one day it may be real beneficial. If you drop down to 30' to tie off a boat, (not that I know why you'd want to do that instead of simply dropping an anchor) and then immediately surface, then no - you likely don't need a safety stop after a bounce dive. The goal is to eliminate the nitrogen absorbed by your body during bottom time - if you have no bottom time, in an NDL scenario it's unlikely you have much absorption either.
2. "...because my computer can figure out my deco." This statement, and others like it, is precisely why I get chapped about questions from noobs regarding which computer they should buy. Yes, your computer can figure out your deco. But if you haven't already figured out your deco in advance, how do you know you have enough gas remaining to perform the deco that your computer prescribes?
People start depending on their computers to 'figure out their deco', which is exactly what is wrong with noobs diving with computers. They let the computer run their dive, surfacing when it tells them to. They don't plan for themselves.
You should always calculate your dives before you dive them, using either a table or using a decompression software such as V-planner. This is called 'planning the dive'. Somehow I suspect you're not to the point of planning
decompression dives just yet, but you should be doing the exact same process for No Decompression Limit (NDL) dives. Planning the dive is what tells you if you need a safety stop or not. If you're close to the limit of time and depth on your table, you need a safety stop. If you're NOT, then a safety stop is often still a good idea, particularly if you're shore diving and have a reef or a beach area to poke around and look at stuff for three minutes in very shallow water.
Once you 'plan the dive', the next obligation is to 'dive the plan' - e.g. don't ignore it and go do something else, thereby requiring your computer to calculate a deco schedule for you. Dive the dive you planned.
The consequences of not doing so include one day looking at your computer, which tells you that you now need three stops (30/20/10) for a total of 11 minutes, only to discover that you're at 400 psi and you don't have enough gas to perform those stops.
Know what you're going to do before you get in the water, and then after you get in the water do what you preplanned. Life is much easier that way.
Dive safe,
Doc