Ascent rates

[boulderjohn]

You prefer a reel for deeper dives as opposed to a spool? On the few deeper ow dives I've done I just carry a reel. I think it's easier and safer, especially from depth. I've had multiple people poo poo a reel and tell me if I can't use a spool then my skills suck. I ignore them

A spool with 400 feet of line on it is somewhat unwieldy.

 

[PfcAJ]

You prefer a reel for deeper dives as opposed to a spool? On the few deeper ow dives I've done I just carry a reel. I think it's easier and safer, especially from depth. I've had multiple people poo poo a reel and tell me if I can't use a spool then my skills suck. I ignore them

If you’re too deep to use a spool, use a reel.

Most ow tech dives are too deep for a bag to reach the surface from the bottom if you’re using a spool.

 

[rddvet]

A spool with 400 feet of line on it is somewhat unwieldy.

If you’re too deep to use a spool, use a reel.

Most ow tech dives are too deep for a bag to reach the surface from the bottom if you’re using a spool.

agree with all the above which is why I didn’t understand people’s aversion to a reel. It’s the right tool for the job deep

 

[kensuf]

You prefer a reel for deeper dives as opposed to a spool? On the few deeper ow dives I've done I just carry a reel. I think it's easier and safer, especially from depth. I've had multiple people poo poo a reel and tell me if I can't use a spool then my skills suck. I ignore them

Yeah, I use a light monkey 250' reel for stuff shallower than 150' and a 400' reel for everything else.

 

[treasurehunter]

Working in feet I was trained to count in my head by seconds. 60ft/min= 1sec/ft, 30ft/min= 2sec/ft and 10ft/sec=6sec/ft.

The secret to controlling a fixed assent rate is to maintain a negative buoyancy and fin up, we used to half our depth very fast and then slow to 60 fpm to the first stop with no computer.

This is basically the way I do it and gives good control.I stay horizontal and very slightly negative so i don't need much fining force to start moving up. Keep my computer or bottom timer in vision and start ascending and counting.
eg: with 30ft/min I count by saying to myself " 1 and 2,1 and 2, 1 and 2" and I move one foot up at every count of 1 and 2.
10ft/min I count "1 and 2 and 3 and 4 and 5 and 6 and I move up one foot.
I don't use the 1 one thousand 2 one thousand method because I find the timing is off.

60 ft/min and 30 ft/min is and feels fast and I keep constant control of my wing. As soon as I feel my buoyancy is taking over my accent from my fins I release air from wing to give back control to my fining. It works fairly precise for me.

 

[irycio]

.I stay horizontal and very slightly negative so i don't need much fining force to start moving up..
.

i struggle to see how staying horizontal and finning you can start moving upwards. No sarcasm here, I’d just like a better description since I don’t see how you could fin while staying horizontal and not move forwards - I want to be able to ascend vertically without going anywhere laterally and finning would seem to only help if I was totally vertical.

 

[treasurehunter]

Well I’m not very good at descriptive writing but here it goes.
When i start my accent I use a combination of breathing,buoyancy and finning.
I take a deep breath to start the accent and at the same time Fin a kind of modified helicopter turn except I rotate my shins and ankles, so as I arc both my fins apart and then back together, my fins are pushing water down wards. If I am diving in current I will incorporate some thrust as needed as in the frog kick.
While I’m ascending I keep my wing inflator in hand and release as I feel the buoyancy of my wing taking over my accent. The finning is not the major contributor to my accent it just keeps the rythme of the timing. I do this in still water and in current and it keeps me where I want to be. A little movement forward is not a big deal , you can compensate by turning around if you must.
Being vertical for me takes away a lot of control. When I’m horizontal I have my wing inflator in hand my computer or bottom timer always in view, and it cuts a lot of the current drag.

 

[GF99/99]

Here is my 2 cents I'm sure many will have a different opinion but why are you so focused on hitting 9m/min especially on such a shallow dive. If your only doing a 45m dive for what say 30 min bottom time your first stop is probably around 18m'ish its pretty much a wash out in deco time if you travel at 6m/min or 9m/min so why not just play it safe and ascend at a slower safer speed so what if you rack up 2 more minute of deco. Yes I agree when you hit your run time/turn time/whatever you want to call it you need to start ascending and realistically good practice is to always leave a minute early but that does not mean you need to be so focused on hitting this magical 9m/min. I am assuming that if you guys are doing 45m dives you are all ANDP certified and maybe new to tech diving or only do 20-30 tech dive a year so obviously you should not expect your buoyancy and accents to be perfect don't put so much pressure on your self just go for a dive and have fun and dive on the conservative side just shoot for 6m/min and you can even plug 6/min in your planning software. Remember slow is smooth, smooth is fast. With time/practice you will get much better and if you really want to nail 9m/min you can do it but practice with 6m/min especially on such shallow dives its much safer. Yes for deeper dives maintaining the planned accent rate is very very important but for 45m even 55m dives I would not stress about it too much and once you are doing deeper dives you will have moved to the next level and by they you will be a lot more proficient at accents and it will be second nature. Remember your pressure differential is greatest in the shallows, I think alot of people forget about this. I actually plan deeper dives anything below 100 meters with the intent to only go 6m/min in the shallows usually from 21m up its 6m/min or slower especially from 12m and up I just creep. At this point your on such high O2 the amount of deco your racking up is negligible and your intermediate tissues are so saturated with helium you just want to take it nice a slow. But at depth since the pressure differential is much lower (depending on the depth you at) you can actually speed up accent rates to get off the bottom as quick as possible to reduce tissue loading. Sometime when shallowing up from depth to say 120m meters ill run 15m/min then from 120m to 80m'ish ill run 12m/min and then from 80m-21m the standard 9m/min

I don't know what software you use but I'm a big fan of multideco and accent and decent (dont forget about these) rates are very interested to play around with when your doing deeper dives and you can put in you accent rates based on depths. I encourage you to play around with the software and see what 6m/min vs 9m/min does on a 45m dive. I bet its very very little difference so for the extra 1-2 minutes you have to hang out on deco you get a nice slow safe accent rate and your not stressed about trying to get 9m/min and you will be a lot more focused on the dive, your buddy, situational awareness, etc. then getting tunnel vision trying to get this magical 9m/min. Just keep diving and having fun and it will eventually come natural and you really wont even think about it.

 

[boulderjohn]

Sometime when shallowing up from depth to say 120m meters ill run 15m/min then from 120m to 80m'ish ill run 12m/min and then from 80m-21m the standard 9m/min

There was an extended discussion on another forum about a very deep dive (180 meters) on which the diver got seriously bent. The diver posted the details of his dive so that there could be an extended discussion about it. He had used the philosophy of doing the deepest ascents faster than the shallower ascents, just as you describe. There is nothing inherently wrong with this approach--it makes sense, in fact.

As I recall the discussion, the consensus was, however, that his dive plan from decompression software assumed a steady 9m ascent rate. In shallow decompression dives, it would make little difference, but on a dive as deep as that, it made a big difference. The plan's first stop assumed he had spent a certain amount of time ascending (and off-gassing). If you input his actual ascent rate, the software calls for the first stop to be deeper.

You can see a similar issue with people following decompression software plans on deep dives when they descend faster than the software is set for. Let's say you plan a dive to 90 meters/300 feet, and the software has a 15 meter/50 foot per minute descent rate. You are planning 20 minutes before beginning the ascent. You instead descend at 30 meters/100 feet per minute. (These are not random or unrealistic numbers--I had this discussion with someone who loved to do rapid descents like that, without adjusting his planned ascent profile.) At the planned descent rate, it takes 6 minutes to reach the bottom. At your actual rate, it takes 3 minutes to reach the bottom. At the planned rate, your first 6 minutes of diving were at an average depth of 45 meters/150 feet. At the actual rate, your first first 6 minutes were at an average depth of 70 meters/225 feet. That will make a significant difference in the dive profile.

 

[GF99/99]

There was an extended discussion on another forum about a very deep dive (180 meters) on which the diver got seriously bent. The diver posted the details of his dive so that there could be an extended discussion about it. He had used the philosophy of doing the deepest ascents faster than the shallower ascents, just as you describe. There is nothing inherently wrong with this approach--it makes sense, in fact.

As I recall the discussion, the consensus was, however, that his dive plan from decompression software assumed a steady 9m ascent rate. In shallow decompression dives, it would make little difference, but on a dive as deep as that, it made a big difference. The plan's first stop assumed he had spent a certain amount of time ascending (and off-gassing). If you input his actual ascent rate, the software calls for the first stop to be deeper.

You can see a similar issue with people following decompression software plans on deep dives when they descend faster than the software is set for. Let's say you plan a dive to 90 meters/300 feet, and the software has a 15 meter/50 foot per minute descent rate. You are planning 20 minutes before beginning the ascent. You instead descend at 30 meters/100 feet per minute. (These are not random or unrealistic numbers--I had this discussion with someone who loved to do rapid descents like that, without adjusting his planned ascent profile.) At the planned descent rate, it takes 6 minutes to reach the bottom. At your actual rate, it takes 3 minutes to reach the bottom. At the planned rate, your first 6 minutes of diving were at an average depth of 45 meters/150 feet. At the actual rate, your first first 6 minutes were at an average depth of 70 meters/225 feet. That will make a significant difference in the dive profile.

Thank you for the response, Its nice to hear that others have a similar thought process on this as I do because there is very little info on sub 100 meter diving and it really is just about talking with others what worked for them and experimenting with your own body and seeing what works for you.

Yes I 100% agree with your comment about decent rates that's why I mentioned it in my previous post that this is often over looked and for deep dives this is very very important too. I always plan deep dives with a fast decent rate usually use 30m/min and thankfully shearwater now has a nice decent rate meter they added in maybe 2 software updates ago. But I think the best feature on the shearwater is the timer the second I go under I start the timer and when I hit my targeted bottom depth I check the timer (down to the second) to see if I'm early or late based on my plan on Multideco and adjust my dive accordingly. This is very very important as you mentioned because if your early its incredible how much extra deco you can rack up just from spending 1 minute extra at depth.

As I mentioned be for the software is a very very powerful tool and you can play around with it a lot and decent/ascent rates always need to be checked and you need to put in realistic values and then carry out your dive based on those. I think decent/ascent rates and BO gas SAC's are the two most over looked things in dive planning. Case in point sound like the guy you were talking about did not even bother to check this and if you doing a 180m dive these are the things you need to be checking. Anyone, even a brand new diver can drop down to 180 meters but not everyone can come back up safely. Its taking the time to plan a dive double check, triple check things and have the skills and knowledge to be able to problem solve at that depth that make a good diver. Rookie mistakes like just planning your whole dive at 9m/min for a big dive like that should not be happening and if you are making mistakes like that you should not be diving to those depths not to sound rude but if someone is making silly mistakes like that for dives that serious he probably had it coming, over confidence and complacency are what get you into trouble. When you start diving at these depths its not diving its underwater survival and its how good your problems solving skills are at those depths especially when your on CC.

Do you by chance have a link to that accident I would be very interested in reading about it.