Do you need a SPG if you have a transmitter?

[@MiladCerkic]

Just returned from a diving trip in the Philippines and, as fate would have it, my Teric's AI antenna gave out after just 3 days underwater 😞. Lucky for me, I had my SPG stowed away in my dive bag. It really saved the day, allowing me to continue diving. This experience was a solid reminder of why it's always good to have a backup. Never underestimate the value of an SPG, even in the age of tech!

[@marytagliaferri2852]

My husband and I are dive buddies and both use the same type of wireless computer. Our computers are paired to each other's transmitter so we can read each other's air underwater - a good backup to any transmitter failure.

[@Sherwoody]

With an SPG, a dead battery won’t ruin your day.

[@Cameronpov]

How far away can you get before it disconnects from your buddy's transmitter? And is it constantly beeping when it loses connection?

[@CrazyGuyBlahBlah]

@@SherwoodyA dead SPG can. I’ve had to replace an SPG and haven’t had to replace a transmitter.

[@EricBoren]

Surprised nobody has mentioned this: with an SPG you can watch the needle when you test breathe your regulators before entering the water. It gives you a really obvious signal that something isn't right if you see the needle wiggle or move rapidly (at all, really). That's something you simply can't get from a transmitter.

[@OrenNoah]

Yep. I have a AI transmitter, but I ALWAYS watch my SPG when test breathing off both of my refs before every dive to assure myself that my gas is fully on. I’ve found that a DM actually turned my air off instead of on without my knowledge, literally behind my back.

[@amadeuss3341]

Pressure will drop on the screen as well if your air is off. Best solution - make sure your air is on in first place.

[@MrNeobuxer]

That's not accurate at all :) the reading will fluctuate on your screen and start dropping noticeable just like an SPG.

[@fireman_spock669]

I've kept a single gauge console as an emergency backup to my transmitter too. It's come in handy once before. I route the hose through my bcd to eliminate the risk of dragging it, but it's easy to get to if I need it.

[@rwa8884]

Around the time I started thinking about removing my SPG and only using a wireless pressure transmitter, the transmitter failed while on vacation. My computer still worked as a non-air integrated system, though, so the trip wasn't ruined. Otherwise I would have had to waste time figuring out how to buy or borrow a replacement SPG. After that, I did replace my original SPG with a compact one. They make some pretty small ones these days that work well as backups. So it's really just the extra hose you have to contend with. In my opinion, that's a small disadvantage to put up with for the redundancy it gives.

[@zarlorz]

You make it sound like you consider your SPG your primary, and the transmitter is the "nice to have". I tend to think of it the other way around where the transmitter is the primary in which case the SPG would just be a backup (and as a potential failure point, for all the points you mentioned, the transmitter alone is what I prefer). I have a brass-and-glass SPG available, but it's a backup in case the transmitter were to ever have a problem (which from videos and interviews with divers far, far more experienced than I am, seems to be almost never these days... not as true a few years ago, but the quality seems to have improved massively). I think it was a DiveTalk video where I think Gus interviewed a bunch of professionals at a conventions to see what they dove with, transmitter, SPG or both, and there were various reasons given for all of those configurations but it seemed like the most common was really just a transmitter alone. Overall, though, I would certainly agree it just depends on the diver, the kind of diving they might be doing, and personal preference more than anything else. Don't forget that it's worth noting that as a mechanical device SPGs do have the potential to lose accuracy over time (it's just a mechanical spring, after all) so they have their own set of issues as well.

[@twoknife]

I quite like using the SPG to check that the tank is full. It is just a bit faster than turning on the computer and waiting for it to pick up the signal. Also easier in a buddy check and is suitable for finding a not fully open tank valve. I don’t usually bother looking at it once in the water though.

[@TnEEn]

Button spg :D

[@twoknife]

@@TnEEn I will probably buy some when I take the sidemount class

[@js4120]

I have both on my sidemount since they're not in the way and easy to access. Ive had issues with a reg that was first thought to be transmitter. Good diagnostic tool.

[@RemoteViewr]

To use AI-only increases the negative impact of any loss of / damage to / failure of your computer. If you no longer have depth info but do still have air info (via SPG) you can still complete a buddied no-deco dive and/or solo ascend a no-deco dive relatively safely (if you’re capable of watching bubbles and counting). Having a redundant SPG gives benefits for very little cost. Alternately, go AI-only and have redundant computers

[@amadeuss3341]

I keep spg tacked behind my back, the only time i look at it to check pressure on new tank. , it's there purely for a situation if transmitter goes out due to low battery or something, since it's hard to get new batteries in places i go.

[@bloodymarvelous4790]

I have both. I'm still quite partial to analog gauges. It's a much more natural way of reading values. I don't need to know I have 143 bar, the needle being closer to 150 than 100 tells me more than enough. However, I do love the additional information a digital gauge gives you. GTR and SAC are nice to know. Giving a visible warning on my computer is a nice thing too. And you'll know immediately when your transmitter isn't working: It won't display a value. As for failure points vs redundancy: All redundant hardware introduces failure points. If you have both on a single first stage, you're probably not doing a technical dive. If you're diving doubles you can put one on each stage, providing full redundancy. If you're using transmitters on sidemount or stage cylinders, they can assist with cylinder switching, or alert you well ahead of time of issues with deco gasses. Having an analog SPG as well is never a bad idea. Transmitters can lose connection or run out of battery. Being able to still monitor your gas with an analog gauge can help you get out of an overhead environment safely, or give you piece of mind when performing a safe ascend. Or you may just finish your dive on your SPG like you would on your a.i. computer. I touched on the unimportance of accuracy, but it is true a bourdon tube in an analog SPG does straighten over time, giving you inaccurate readings. Having a transmitter in addition will help you keep track of the accuracy of your analog SPG.

[@norbertosalazarzagaglia6216]

Thanks Mark; I just bought a perdix 2 ti with the swift transmitter and wanted to get rid of the SPG due to weight when traveling. but my friend told me not to-He is teck and I only ADVANCE. I may keep both and depending if going abroad ....if airline allow only 20kg....I see

[@hikeDiveEat]

I hope you love your Perdix as much as I do. Absolute pleasure to use. I don’t dive with an analog SPG, but keep one in my kit in case AI fails.

[@norbertosalazarzagaglia6216]

Thanks a lot I will do as you said@@hikeDiveEat

[@utubeflyer]

I use wireless and button spg's on my sidemount set - transmitter only on open water recreational dives - and transmitter with 2" brass and glass in doubles. I'm moving more and more to almost exclusively sidemount diving and until I have a failure I dont think I'll be changing that setup here in Florida. Keep up the great content!!!

[@scubatom8232]

For some strange reason I loose communication on night dives on my Shearwater Terec/ Swift transmitter. Only happens on night dives.

[@walterbirriel7620]

I dive a Shearwater Teric and a Cressi Digi 2 Electronic SPG. This saved me on a dive where the Teric ended up with a bad battery and quit mid dive on my first dive of the day. I was still able to finish the dive, get to the surface and calculate my second dive with the conventional Navy dive table. The Digi 2 gave me max depth, total dive time, and obviously air. Just my 2 cents, this is my personal redundancy. Yes the Teric had to go in for service, which by the way was absolutely amazing and I will never use anything but Shearwater.

[@miguelangelpaya7149]

Hi Mark, Why if you can attach the transmitter to the first stage directly some people use a short hose instead?

[@ScubaDiverMagazine]

You can attach a transmitter directly to 1st stage but, many divers use a short hose to avoid the transmitter being grabbed like a handle and breaking. As long as you know that you'll be the only one handling your equipment and won't use the transmitter as a handle then it's fine to fit your transmitter directly to your 1st stage.

[@Cappaghgrove]

An unrelated question. If there are any lucky so and so types who have dived Galapagos, Cocos and Malpello, would it be possible to say which one is better and why????

[@stefandudda4958]

hello Mark 😊 I went on a wonderful liveaboard in Oman. Waters there are teaming with exciting life and they are deep. Some of the dives were proposed to be beyond Nitrox depth. So, 21% air would be the safer choice for those deep dives. However, with 4 dives a day, I‘d prefer 32-34% for most dives for better blood-nitrogen management over time. Should it be ok to start with 21% dive and then continue with 32% for the shallower depths? Do you have any advice on mixing air with enriched air tanks during consecutive dives, please? Thank you! 🤩

[@ScubaDiverMagazine]

Yes, most liveaboards I've been on have a simple system where cylinders will be filled with air unless there's a tag around the neck and you're free to choose air or nitrox for the next dive. You do need to think about your previous mix though. Most liveaboards will have a Membrane Nitrox system, so your cylinder must be as empty as possible from the previous dive so it affects the next mix as little as possible. If your cylinder has some air inside and you top it up with Nitrox then the air will dilute the nitrox. The more air that's left inside from the previous dive the less nitrox they can get in. And vice-versa: if your last dive was on 32% and you fill it with air then you'll still have a bit more O2 so you still need to test your mix to know exactly what's in your cylinder.

[@japanskakaratemuva5309]

i use both. more often then once so far for a year of use transmitter battery failed on one just to fail during the dive on the other (yes SM). the benefit of having the transmitter is extra data and no needless rash lamp movements while checking spg and confusing the diver in front for signaling a problem or emergency.

[@japanskakaratemuva5309]

so having a backup proved for me more reliable then having another failure point.

[@tazccl]

I have one for a back up.

[@pablorivera376]

I prefer an SPG, with a transmitter you have to worry yet about another battery for something vital as your air pressure. It is fragile and easy to lose. I am a recreational diver who like to rely on electronics as less as possible. I use a computer but also a mechanical automatic diver's watch and even consult my decompression table. Most new divers don't even know how to use a decompression table anymore so if their computer fails they cannot dive, but I do!

[@tontsyy]

#askMark where can I get an orange backplate harness? For example similar to the tecline. If I were to buy coloured nylon webbing, is the centre hole crucial to have?

[@ScubaDiverMagazine]

You can make the hole in the webbing very easily, just stamp a hole through with a heated hole punch. Heating it will make the nylon melt and prevent the edge of the hole from fraying. The hole isn't 100% essential but, the webbing usually covers a hole in the backplate that you need to mount twins or a STA. If your backplate has multiple holes and you use one of the others then the hole in the webbing isn't essential. Searching online for harness webbing can be tough because most sellers don't note the stiffness and it's typically medium to soft which is only good for crotch straps because D-Rings will slip on them so you need the stiffer nylon 2" webbing. Black is super easy to find, other colours harder to find, ask some local diving forums and your local dive centre, they should be able to help you find somewhere to find orange webbing.

[@Beets1e]

#askmark I will soon be finishing my course. I am looking at diving computers i understand air integrated is better but at a price premium. Is a non a.i dive computer just as good with a few less bells and whistles? Thanks

[@ScubaDiverMagazine]

Sure, there are a bunch of great computers without AI. It's a nice feature to have but it's not essential. A few models such as the Scubapro Luna 2.0 have two versions, one with and one without AI. The Shearwater Peregrine and the new Tern have non-AI versions and they all have everything that a diver will need, they just won't connect to a transmitter and you'll need to check your SPG.

[@patrickmessina08]

What brand of 6” HP hose and air spool would you recommend to use for connecting the transmitter to the first stage?

[@ScubaDiverMagazine]

Most hoses are pretty similar and trustworthy across the brands. Miflex are best known for braided hoses and their HP hoses, while skinny, are nice and flexible. I don't look very hard at the brand of Rubber HP hoses, they're all very similar. The same for swivel pins, you won't notice much variation across brands. It's typically whatever your LDS stocks

[@greglyon1201]

A transmitter failure does not mean that the dive computer has failed. If you have a SPG backup you can continue the current dive as well as the rest of the dives. My swift transmitter has failed to connect at times, but my teric is still functioning perfectly as a computer sans displaying air. With a hose SPG no big deal, without it dive(s) are over.

[@Broughden]

"Second failure point" ?!? Yeah that's the point. If your computer with air integrated transmitter fails, if you have an SPG then you can still continue the dive safely. Also what if it's the first dive of the day? Unless the dive boat brought a spare computer for you to use, then your day is done and all you can do is ride along on the boat as others are diving.

[@CrazyGuyBlahBlah]

No. No more SPG for me.

[@kylefleming2171]

#askmark Can you explain suit squeeze Have been told it’s just uncomfortable, then also told it’s dangerous Cheers for the content 👍

[@ScubaDiverMagazine]

It can be dangerous and painful if you don't remedy a suit squeeze. But on most dives it's never an issue because the diver simply adds some gas to their suit. Because your drysuit is a sealed air space, any gas volume inside will reduce under increased pressure around you when you descend. Without adding any air to your drysuit as you descend it starts to feel like you're being vacuum packed and squeezed. If you continue down it will only get worse and as the suit creates creases it can pinch which can be painful. It's more of an issue with membrane drysuits and with thin undersuits compared to neoprene drysuits. Just like your mask squeezes as you descend, you feel it long before it becomes painful and all you need to do is add a little gas.

[@amadeuss3341]

Imagine you don't equalize your mask all the way down , similar feeling , but your whole body feeling it

[@relentlessadv9521]

I inflate my dry suit to compensate when I feel a little squeeze. It is gradual. It's another task that requires awareness underwater, so the key is avoiding task overloading and having good trim and buoyancy skills prior to taking a dry suit course.

[@TnEEn]

Shot answer, yes! Transmitters can fail mid dive for absolutely no reason

[@DarthMuffin007]

Agreed. Redundancy.

[@Cappaghgrove]

#askmark could you review the scuba pro Luna computer?

[@ScubaDiverMagazine]

Sure, I'll see if I can get one from Scubapro to play with

[@Cappaghgrove]

@@ScubaDiverMagazine thanks Mark. It would be interesting to know how it compares to the G2

[@arjanwesselink3418]

The fact that you have a digital readout does not mean more accuracy.

[@MrNeobuxer]

#askmark Hello Mark, I was looking to buy an umbilical dive torch and was looking at the Halcyon Focus 2.0. However, the Apeks Luna X is significantly cheaper (yeah.. believe it or not, Apeks is cheaper...) and I love my Luna Advance build quality. Do you think you can make an honest unboxing/review on the Luna X?

[@ScubaDiverMagazine]

I'll ask if I can play with one for a video. The rest of the Luna range is reliable and I've never seen the fascination with the blue H, they're a good brand but not the only brand out there.

[@bloodymarvelous4790]

I recently bought one. I compared it to a Luna ADV in the store, and found the hot spot on the Luna X to be a lot brighter, even though the Luna ADV produces 3600 Lumen, and the Luna X 3300 Lumen with both hot spot and flood. It penetrates murky water much better because there's less backscatter, and you can even turn the flood off to reduce backscatter and increase penetration even further. Also, I managed to get a really good deal on the Luna X. I only paid € 999 instead of the normal € 1199. (It's a lot more expensive in the US.) I would recommend turning the head around on the handle. It balances the handle out better, and allows you to span a 6mm bungee over the top as a makeshift DPV loop and double ender attachment point. Plus you can put a couple of line markers on it as well.

[@MrNeobuxer]

@@bloodymarvelous4790 Ah thanks for that! I also see an offer for 999 € (with the exception of rebreathers, I find all diving gear more expensive in the US) but I am quite hesitant since there are barely any reviews online for Luna X. That said, there were barely any reviews and people shouting how expensive Apeks Luna range is, until I got one (primary adv) and realised how much of a longterm reliable investment it is. The goodman handle is quite good, already got that with the ADV, and it's much better than any goodman handle i've seen in terms of versatility and quality. Do you find the cable to be too long? How easy do you find it to switch light output settings under water?

[@scubatom8232]

For some strange reason I loose communication on night dives on my Shearwater Terec/ Swift transmitter. Only happens on night dives.

[@scubatom8232]

For some strange reason I loose communication on night dives on my Shearwater Terec/ Swift transmitter. Only happens on night dives.

[@scubatom8232]

For some strange reason I loose communication on night dives on my Shearwater Terec/ Swift transmitter. Only happens on night dives.

[@scubatom8232]

For some strange reason I loose communication on night dives on my Shearwater Terec/ Swift transmitter. Only happens on night dives.