Minimum BCD Lift Capacity? | #AskMark #Scuba #Q&A | @Scuba Diver Magazine
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1
Mohamed Al-Busaidi
#askmark hello mark it’s me again 1st of all congrats on the move wish u all the best.
My question is about bcd lifts especially hybrid bcd’s or some call it back inflated bcd. What would be the minimum lift requirement for a single 12lit aluminum tank , 2kg back pocket weight , 6 kg belt or sls, accessories like DSMB, I’ve seen ranges starting from 24lbs to 75 lbs.
sorry I know it’s a long question but I would u to explain thanks and have a good day.
I haven’t found a clear video so far or an explanation on what is the minimum lift capacity.
2
Yves Morin
#ASKMARK what is the best reel for mapping a site ? 100 meters long
3
Jarod Callander
#askMark can you please compare the Teric and their Perdix 2 and highlight any different features? Thanks very much.
4
adam collinge
#askmark
What happens if you forget to put your regulator in dive mode and do a full dive in pre dive mode ?
5
Ashis Sarkar
Hi Mark. Thanks for another great video. #ASKMARK. Would you suggest a backplate and wing over Jacket style BCD for new advance divers.
6
Alexander
#askmark
Hi Mark, in my last dive I didn't had an antifog spray so I read in the internet that I can use baby shampoo instead.
In the dive (after 20 minutes) it started to made a lot of bubbles in my mask and to blow the mask out didn't helped. I felt not really comfortable with that but I didn't want to end this dive, because I had just the possibility to that one dive in this awesome spot. What would you recommend to do in such an situation? Should I stop the dive in this point or should I try to enjoy it next time?
00:00 – Intro
00:58 – BCD Lift
05:59 – Mapping Reels
08:48 – Teric Vs Perdix 2
13:09 – Regulator Dive Mode
15:34 – Backplates for new divers
18:51 – Defog Solutions
The Venturi effect is where the pressure drops when air moves from a low volume to a high volume environment. In a regulator this sucks in the diaphragm and keeps pressure on the demand valve, which keeps the air flowing until it reaches equal pressure.
In practical terms, this means that the demand valve remains open until you close your airway, without the need to continue exerting suction to keep the valve open. This reduces the work of breathing as you only need work to open the valve in the beginning.
The downside is that it creates a freeflow if the demand valve is opened when the regulator is not in your mouth. There will be a constant lower pressure which will keep the diaphragm sucked in and the demand valve open.
Regulators without a Venturi switch will have a deflector that will redirect the air towards the diaphragm. When the demand valve is opened, the air flow will push against the diaphragm to release the pressure on the demand valve and close it. With these regulators you will need to constantly create negative pressure by sucking air in order to keep the demand valve open. Much like you need to keep sucking air in on the surface to fill your lungs.
Regulators with a Venturi switch can rotate that deflector so air can move unimpeded. So having the Venturi switch in the Pre-Dive position is like breathing from a regulator without a Venturi switch. Having it in the Dive position when you’re at the surface or jumping into the water, can cause a freeflow when the purge button gets depressed or there is a lower pressure in the regulator than in the surrounding water.
about pre-dive mode: I got a Scubapro Regulator. I went diving in Spain a week ago, I forget to change to dive mode, I did my deep dive certification, so if you dive 30 meter or deeper you realize it’s harder to breath. I don’t know if it feels similar as if you took a unbalanced first stage with you to 40m, we should test this.
I should really take the risk to dive deep with a balanced and unbalanced first stage, then I could test this out.
But if you don’t dive deeper then 20m you don’t realized much if it’s dive or pre-dive.
to make my experiance short, pre-dive mode:
>25m medium difference
+/- 30m you statt to breath harder, you use more air, I would say you would dive Just 20min instead of 25-30 min, it’s just a guess.
>40m you feel it, you really strugle a little bit.
But those are just my experiance, I wonder if others had similar experiance.
#AskMark Thanks for all the helpful information you are always sharing, I love your channel. I am a new diver, I am looking to buy a bcd, and Im trying to figure out the right size. My concern is my body weight (In Pounds) when it comes to the sizes of BCDs, as well as Not understanding what it means when it says Lift(N) on a sizing chart.
Your best option for trying on sizes, is to visit your local dive store so that you can try some on. If you can remember the size of your school BCD that can be a helpful indicator of roughly what size to look at. The sizes are fairly similar across brands.
The body weight in size charts are a rough guide If that’s the only measurement that doesn’t fit on a size chart I wouldn’t worry. The chest and waist measurements will be a better indicator for size of a BCD.
You don’t really need to worry about the Lift Capacity of BCDs right now. All recreational BCDs will have enough lift for a single cylinder setup.
The Lift(N) on a sizing chart is related to the size of the bladder. With some BCD’s, the larger the size, the larger the bladder, and the more lift it can produce. That lift is not related to your actual weight. Like Mark explained in the video, you can weight yourself so that you don’t actually need a BCD. The lift capacity only comes into play when you’re carrying a lot of heavy gear like staging cylinders, or if you find an anchor on your dive that you decide to keep as a souvenir.
Hey Mark please do a comparison between the Perdix 2 and the Apeks DSX. THANKS!!!
regarding “ideally not needing a bcd” he speaks truth… it feels good once a diver reaches that stage.
#askmark Hi. How do I move backwards if I get too close to corals?
There’s a backward fin kick where you extend your fins backward, turn your fins out flat and then pull them back. It’s not particularly fast and does take some practice but you can reverse in the water.
This is quite a good video for how it should look:
https://youtu.be/EbuxOhlNlh4
#askmark having accidentally set my Suunto D5 to gauge mode instead of free for some casual snorkelling before some dives, I discovered that if you use gauge mode at all it will immediately lock you out for 48 hours – why is this a thing and in what circumstances is it useful? Why would you want a computer to be one use only?
GREAT question! Gauge mode turns the computer into a bottom timer which is handy for diving on a rebreather. It’s a little too long to explain in a comment but, Rebreathers can adjust the gas mix that you’re breathing during the dive and a computer set to Gauge mode is a handy backup that won’t alarm.
Without recording your decompression in Gauge mode the computer knows that you’ve been diving BUT doesn’t know how much gas is dissolved in your tissues. That’s why it locks you out of other modes for 48hrs.
I’ll explain better in a future episode…
#askmark I dive a Bare X-Mission drysuit that has a plastic zipper. So…no wax, wax the end, wax the whole thing? Silicone lube? The internet has all the above suggestions. Do you have a definitive answer?
I have a Fourth Element Argonaut with the plastic zipper – I just put a small amount of T-zip ‘wax’ on the very end where the zipper pulls home. That’s it.
#askmark What are the practical differences between a mk25 and other scubapro diaphragm regs (like mk17/19)? And the maintenance cost of piston vs diaphragm? Thanks!!
#askmark on a 4 day liveaboard is it necessary to rinse regs off at the end of each day or the end of the trip ?
It can’t hurt to rinse them off every day, but thoroughly rinsing them at the end of a 4 day trip should be fine too.
#AskMark I hear about how you should have a backup of everything, including your dive computer. along with how you should buy a dive computer that can grow as your skills do…. but if you should have two; wouldn’t it be sensible to start out with a cheaper (something like Cressi Leonardo) as your first dive computer then just have that become your backup computer later on?
Not many people get a back up dive computer, but if you have two, then sure. Just make sure they’re using the same algorithm, so they don’t contradict each other.
A back up dive computer is only really used when diving in overhead environments or venturing into technical diving. Though by that stage you should have a dive plan with you, which you should be following at all times, it’s a good idea to have a back up computer to safely guide you through your decompression stops.
I use the “no more tears baby shampoo” type. Dilute it with water (around 20 soap to 80 water) and put it in spray bottle. Spray it to the mask and let it soak or even dry for a few minutes. And before wearing just dip it quickly in the water. Most new divers they actually rinse it clean so there’s no more soapy film to prevent from fogging.
Good stuff 👍
@Mohamed Al-Busaidi There is a good ISE video on sizing your wing/BCD https://youtu.be/4D_nVupptm4
In short = size BCD as minimum to compensate for weight of your gas used during dive (2kg for single tank) + needs to float your gear on the surface when you remove it + safety margin for staying above water. You should aim for lowest amount of weights possible to keep you neutrally buoyant at the end of the dive, to have “balanced rig” – one where you have minimum amount of air in the BCD during the dive (see comment on weight of the gas used).
Numerous times I have forgotten to adjust my venturi to “dive” from “predive”. The change in breathability is negligible. Far more important is having good adjustment on the screw valve. It is counterintuitive, the more you screw in that valve the more difficult it is to initiate a breath. A properly adjusted tension can alleviate stress and add significantly to comfort. If you remember to adjust the venturi, great! It will help gas flow once the breath is initiated however it is not as crucial to diver comfort as the flow tension screw. (I dive a Scubapro G250 second stage.)
#askmark Using a Longhose config, angle adapter on the 2nd stage yes or no? And if yes, 90° or 110°? What are the dis-/advantages?
On the long hose: No angle adapter. Having an angle adapter makes donating impractical and complicated. You will need to hold the regulator when you’re donating. It’s better to present the long hose by holding the hose so the OOG diver can grab the reg.
On the short hose: Depends on the length of the hose. If you’re using a 55cm hose it can help control the hose. On a 75cm hose you’ll find the hose will be fighting you when you use an adapter, because it wants to bow out. On a 65cm hose, whichever you prefer.
8 KG lead for warm water dive is a lot……. what is your weight? normally we need like 3-4 KG,
I weight 125 kg and height 183 I use 16 KG of lead