Question from geemac: Would you consider a ‘stand-off’ stick of say 50-75cm x 10-12mm in diameter with bungie style loop that fits over your hand to ensure you don't touch coral reefs or anything with ‘do not touch’ significance in say slight drift, current or tidal movements?
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#ASKMARK Thanks for replying to and featuring my question regarding ‘pointer sticks’ when diving. Never used one myself hence calling it a ‘stand-off’ stick, but I was diving in a group of 10 and 2 divers had pointers which you correctly explained as being incorrectly used to push away from reefs and as anchors when drifting. I’ve since asked our dive team leader about them and he has used one when occasionally diving for Rock Lobsters. Thanks for the tip regarding back finning. Something to investigate, practice and use👍
#askmark Hey Mark, I have a Lifeline Asend Reel 30m. Can you change from 30m of line to 60m with a “conversion kit” or Do i have to buy the whole reel again? Thanks
Interesting… In theory yes. I’ve disassembled a LifeLine Ascend Reel and the handle is the same. The only difference is that the _spool_ is wider on the 60m and the _ line guide_ is longer. I can’t see it as a retail part but, it shouldn’t be that tricky to swap the spool and guide over if you can get hold of the parts.
I’ll ask Apeks, see if there’s a MPN you can ask for at your dive centre to get the parts you need.
RE911124 is for 60m of the orange line only.
@Scuba Diver Magazine thanks it would be really useful if I could just swap the spool and guide. Bit of a fail if this isn’t the case!
#askmark Hi Mark! AI Transmitter vs SPG and should you carry both? My first thought was “yes”, carry an SPG as a backup but I’ve recently seen a lot of good arguments against that mindset. For one, it’s a second failure point and if either the dive computer or the SPG fails you’ll end the dive anyway. Transmitters are also more accurate and you’ll know right away if there’s a problem whereas the SPG you might not.
Yeah, I’m always an advocate for redundancy and if you carry the _minimum failure point mindset_ then you’ll never get in the water. Personally, I dive with a traditional SPG and a Transmitter. As you say: you get the best of both worlds. The analogue gauge can’t run out of power and they’re very reliable. Transmitters are more accurate, give you more information such as GTR and have automated low pressure alarms that can alert you to issues.
Diving both just means you’re covered and have the most tools available to you in the water.
Here’re my thoughts for what they’re worth. I’ve dived with just a traditional SPG and I’ve dived with just an AI transmitter, with no worries. I generally dive with both for redundancy and because I like having gas pressure, SAC, gas time and alarms readily available on my computer. So would I terminate a dive if either one failed? No, unless it’s associated with a gas leak. As for having a second failure point, the maths says redundancy is always safer, unless it is that catastrophic gas leak situation, which with modern equipment and good maintenance is highly unlikely. Or, to put it another way, in several hundred dives I have never had nor witnessed such an issue. So use the AI, and if you like to have an SPG as well there’s no significant reason why you shouldn’t.
I dive with both AI and an SPG and have had my bacon saved by the SPG and able to continue dives that I would have had to abort otherwise. AI actually has a couple of failure points – the transmitter antenna, computer antenna, and the transmitter/computer battery. I’ve had the antenna on my computer fail, but could easily continue my dive with computer depth/time and SPG gas pressure. Yes it’s an additional failure point, but I’m a lot less worried about any HP port/hose failure vs an LP failure of some sort.
also called a lobster tickler
Just got back from Cozumel and our Dive Master used that pointer stick for everything from pointing things of interest out to us, banging on his tank to get our attention, and sticking it in the sand to maintain his position in the drift.
#askmark. Hi Mark, really enjoying this QA. Could you talk a bit about dive computer conservatism in a video? As a new diver i’m very confused on what conservatism setting i should be using. I know I should probably go for the most conservative, but given a livaboard for instance, with 3 or 4 dives a day, isn’t there a risk of getting locked out even though you’re well within the limits when using a high conservatism settting (35/75 on Buhlmann ZHL-16Cfor example) ? I mean, why would my computer offer me low conservatism setting (45/95 ) if that would be unsafe? In my AOW course I ended up using low conservatism on my own computer (Descent MK2S) and using a rental computer on high conservatism just to be sure i never get in trouble.
Sorry for the long question. Loads of love!
This is a very long conversation. The problem here is that there is no _right_ answer when it comes to GF for every diver and every dive always. Every diver’s susceptibility for decompression illness is different and an _aggressive_ GFhi 95 might put you too close to the limit if you are naturally more susceptible. Some divers will use a 95/95 but rely on their computer with a SurfGF function to make sure they’re safely under that by the time they surface.
You also need to take into account the availability of treatment where you are diving. If I’m diving somewhere remote I’ll use a more _conservative_ GF High just in case.
Working out the best GF for you and your dives is up to you but, it is important that you understand the complexities. Here’s a good place to start:
https://dan.org/alert-diver/article/the-many-factors-in-decompression-stress/
#AskMark – Hello from Southern California, water temps are just about ‘warm’ enough for 7m diving season to start again! Here in California you can rent virtually any type of cylinder for a day of diving; steel 100s, aluminum 80s, aluminum 63s, steel 80 or 72s, and on and on. I thought I had it down; aluminum becomes positively buoyant, steel doesn’t, 100 cubic ft is more gas than 80 cubic feet etc. However it appears it’s not so simple, as yesterday I was confused again at the dive shop when the shop attendant started to talk about hot fills verses hp fills, and that in some instances, depending on the type of fill on the dive boat, a steel 100 will end up with not much more gas than an aluminum or steel 80. Can you take a bit of a deep dive into how these cylinder fill variables affect the gas capacity? Thank you, always learning from your channel.
Yup, tanks are tricky. It gets even more confusing when you travel to places like here in the UK where we refer to cylinders by their empty internal volume only…
As far as buoyancy: steel cylinders are easy, they’re always -ve and will always sink.
A hot-fill is basically a rushed fill. As you increase the pressure of a cylinder it warms up, look up _Charles’ Law_ . If you stop filling a cylinder when it’s still warm, the pressure inside will drop as the cylinder cools down. You’ll also lose a few psi when you jump into the cold water and gain a few if you leave a tank in the sun.
I’ll draw up a comprehensive video to try and explain all of the different factors about cylinders and pressure.
Thank you Mark!
#askmark Is it time for a back finning video?
Maybe, I’m away on a course for the next 2 weeks so I can start publishing these kinds of underwater video professionally.
Back-finning feels weird but, is basically flaring your fins out wide behind you and then bringing your knees in and together so your fins pull you backwards. It feels like learning to ride a bicycle backwards and it’s just as slow. But with practice it’s a useful skill to have.
@ScubaDiverMagazine Sadly, I don’t dive anywhere near enough to get the practice in, but I look forward to watching the video once you have been ‘upskilled! Hope you have fun on the course.
I mount my GoPro and torch on a selfi stick and it makes a useful pointer. I’ve never felt the need to use it to put off anything. Back finning and adding a bit of air into your bcd will get you away from just about anything.
#askmark Hey Mark – great videos as always! I wanted to ask your advice on scuba progression for a “beginner plus” diver – I have my advanced open water and nitrox certificates, feel pretty comfortable with buoyancy, and I’m slowly expanding the locations I’ve dived in. Most advice I’ve seen for 25 to 100 dives is “just dive more” which isn’t that helpful. What do you think divers wanting to progress from advanced open water should focus on? I know Rescue Diver is the next obvious certification step, but I care more about developing in water skills. Thanks!
Yeah, “just dive more” is pretty vague… You’re looking to build experience and confidence in more challenging conditions and see how other divers use their dive equipment.
The key here is to do it as safely and as gradually as possible so you’re testing yourself but, not overwhelming yourself.
Look to go on dives with challenges like water movement, poor visibility, different boat or exits. Don’t try to do it all on the same dive. Liveaboards are a good choice to get those numbers in and you’ll be diving on a large boat and a RIB on some of the larger ones. It’s common to do a drift dive as well as night dives and you’re surrounded by other divers who will be using different equipment so, you can chat with them about why they use a certain piece of gear.
You also want to experience when things go wrong. You’ll be a more prepared diver if you’ve seen an O-Ring blow before, or somebody’s fin falls off. the more you dive, the more you’re exposed to when things go wrong and you’re more likely to be able to prevent it the next time because you’ve seen the warning signs before.
I love “askmark” 🎉
#askmark what are your best spots to dive in the uk? I am from germany and i will maybe sometime go visit the UK to go diving 🤩
Please dont stop with Videos! Love em all
Thank you! I love the Farne Islands with their kelp forests and seal colonies. We also have lots of shipwrecks all around the coast. The South and South-West are a safe choice with lots to see.