Howdy! This is my first post here, but I have been doing a lot of reading here and elsewhere on the intertubes.
I am signed up for an SDI OW class at the end of the month. I have no certification at all yet. But, I have been around diving my whole life (Dad, brother, and cousins have all been certified forever), done a lot of snorkeling, and did a discovery dive in Maui last year, which felt completely at home to me.
So, I'm anticipating getting my SDI Computer Nitrox cert either at the same time as OW or immediately after. All in prep for some Caribbean diving in December. I've read up on lots of dive sites I hope to visit someday and many of those are deeper than 20m. So, I'm expecting that I will go on to get Advanced and Deep certs.
I currently have snorkeling gear but no SCUBA gear. I'm trying to decide now what I want to buy before going to Mexico in December. If money were no object I would go ahead and get everything except tanks, but that's not in the financial cards right now. So, I'm debating just getting my own computer, for now - ideally, to have it before my OW class, so I can get used to using it then. Additionally, I am very much a "buy once, cry once" (as I read someone say on here) type of person.
After reading up on everything I can find, what I THINK I want is a wristwatch computer with AI and Nitrox support.
And after reading another thread here with similar questions, I already know that there are a number of very experienced tech divers on here who think AI is useless or worse. And I do understand the reasons for those people feeling that way. But, I also understand the reasons some of the AI proponents like them. For me, just doing warm water Rec diving in the near- to mid-term, it seems like a nice convenience. All my info is in one place. Less hoses to fudge with (if it's wireless AI). More detailed info to help me learn about my own SAC. An alarm to alert me if I'm paying too much attention to the pretty fishes and don't notice that my air has gotten too low.
I understand the more experienced divers don't need that. And, on Tech dives, many want to not have it. But, from my one discovery dive, I know I'll be looking at my SPG a lot, for a while. And, at the same time, I don't yet have the habits that come from experience such that I will always remember to check it often enough. So, for my current needs, it seems like AI is a good idea.
---------- Post added September 3rd, 2014 at 03:44 PM ----------
Also, from what I've read and what I believe I will want to do, it seems like having a computer that supports multiple gases is something I will want. But, I have unanswered questions relating to that subject. They include:
- People use hypoxic mixes for more BT on deep dives. But what does "deep dive" mean in this context? Is a hypoxic mix something that one might use in dives to 40m? Or does that only make sense for Tech dives that go beyond Rec limits?
- For dives to 40m or less, it still might make sense to use Nitrox and pure O2 as a deco gas, right? Or does Rec diving simply never involve switching gases during a dive? (and how said is it that I can read as much as I have on SDI and PADI sites and not already know the answer to that?)
- For dives where a gas switch is done, how is that physically accomplished (in a Rec dive scenario if that is applicable)? Do you dive with a 2-tank harness and a manifold connecting the tanks, and have the Nitrox turned on and the O2 turned off, then turn one off and the other on at the first deco stop? Do you have a completely different reg setup on the O2 tank from the Nitrox tank? Do you just use a side mounted pony bottle for the O2, with its own regulator?
- A bunch of the more expensive Rec diving computers say they support multiple gases. But, it looks like you don't enter a dive plan into the computer to tell it when you plan to switch gases. So, if you're relying on the DC to tell you when your NDL time is up, how can it know to allow you extra time because you're going to switch gases? When you program in all your different gases, does it make assumptions about what you're going to use and the order you're going to use them, so that it will reflect your extended BT capability based on all the gases you're carrying?
- And if you have AI, with transmitters for all your gases, does the DC calculate ATR based on all the gases being available? Or just based on the you're currently using?
- If the DC "knows" that you're going to, say, use Air for the first, deepest, part of the dive, then ascend and use Nitrox for a while, then stop and use O2 for deco, does it prompt you to switch gases at the right times? I guess it can't without AI.
From what I've been reading, I just have the feeling that the idea of using a DC to tell you when to head for the surface, on any dive involving more than one gas, is probably just not going to survive meeting the real world.
OTOH, if you assume that dives will always be NDL dives, to a max of 40m, with only one gas, then a PDC with air integration just seems like almost a no-brainer. Especially if you are going to use a DC anyway, and especially if the AI is via hose. I mean, how much would I pay for the cheapest PDC ($200), plus a console with a SPG ($45)? Versus, say, the Oceanic Pro Plus 2.1, which is hose AI (with a compass) and which is $400.
---------- Post added September 3rd, 2014 at 03:45 PM ----------
Okay, so those previous questions were really just for me to get info to understand how I would (or might) use a computer in the future. Now on to the real questions, which are finally getting around to being relevant to this subforum. :-D
- Several people in the other long thread I read suggested to the OP (who was asking about a PDC for Rec use now and Tech use later) advised him to get a Nitrox-capable PDC and use it in Gauge mode. If you're just going to use it in Gauge mode, why does it matter if it's Nitrox-capable?
I expect many of my dives to be after flying somewhere. And I don't have the budget right now to buy a PDC and a full reg set. So, if I am going to fly and rent a regulator (and BCD), then it seems to make sense that I would buy a wrist-mounted PDC. And one with wireless AI means I probably wouldn't use the AI at first (since I don't see installing my transmitter onto a rental 1st stage. But, after I eventually get my own reg set, then I could use the AI, too.
So, I've been boning up on wrist computers that are AI-capable. The least expensive I've found is the Sherwood Amphos Air, which is on sale for $680, with transmitter. And the next most is the Hollis TX-1, for $750, with transmitter. Or $500, without the transmitter.
The TX-1 looks like it has everything I would ever possibly use. It looks like it would be great for Rec diving and using the wireless AI. And, later, if I wanted to use it without the AI, on Tech dives (if I ever go that far), it supports numerous gases, Trimix, hypoxic mixes, Gradient Factors, etc.. Probably way more than I'll ever use. But, the display alone looks like it's worth the extra $70 over the Sherwood Amphos.
I saw many recommendations on here for the SW Petrel. $850 plus shipping means probably $130 more than the TX-1 (which offers free shipping from LP). I like the Petrel display. But, I think I would actually enjoy the wireless AI and the smaller size and wristwatch styling of the TX-1 more. The TX-1 even supports Buhlmann with Gradient Factors, so I think it would actually support any activity that the Petrel would, which means the Petrel offers no real advantage other than the bigger screen - for me, who has no intention of ever diving professionally, though I may eventually pursue some technical certifications just to allow me to do additional fun diving (e.g. deeper, longer, or caves). I do realize you can pay an extra $70 for VPM-B on the Petrel, which I guess the TX-1 doesn't support, nor have a way to upgrade to. But, as I said, I don't expect to dive professionally, so I'm skeptical on ever feeling like I need that. If I get to that point, I can use V-planner and do my own plan and then use any of these just as gauges, right?
I realize all that sounded like I'm just seeking some kind of validation for a decision that I already made, but I'm not. I'm really on the fence about whether to go "whole hog" with something like the TX-1, or just go inexpensive and have an analog console for pressure (and maybe depth and maybe compass). I just HATE the idea of spending even $200 on a PDC, doing OW certfication and one week of diving in Mexico and coming back wishing I had just spent the $750 in the first place.
Further, if I go the inexpensive route, I'm not sure I could really get away with $200 for the PDC. I have compared dive tables (USN, NOAA, PADI, and some others) and done other reading and have concluded that it seems like the PADI RDP is more conservative than the USN tables (I know it's a generalization, just based on a single dive - but I have also compared repetitive dive scenarios). And it seems like all the different PDCs are at least as conservative as the PADI RDP. Some (like Oceanic and Sherwood) being close to the RDP and others, like Suunto, being signifcantly more conservative than the RDP. Plus, reading on here it seems that Suunto is not well-regarded for reliability. Given all that, I think I want a PDC that is the most liberal - since it will still not be any more liberal than the RDP. Which means it uses the DSAT model. Which means, from what I can tell, Oceanic, Sherwood, and Aeris. And I think I want one that shows O2 saturation level, too, not just N2 (since I intend to use Nitrox). So, it looks like I'd have to spend at least $250. Plus, buy a console with a SPG.
I guess what it comes down to is, should I spend $300 for a PDC and a SPG. Or should I go ahead and ante up to $750 for a TX-1 (with a AI transmitter)? Or $500 for the TX-1 w/o TMT? Or should I do something else? Buy a used computer and a $45 SPG? Like I said before, my most pressing goal is to have my own PDC to use during my OW cert and then diving in MX using rental gear. Secondary is not spending money on something I'll want to replace in the next 6 months or 1 year.
And if you actually read all that.... Thank you!!
I am signed up for an SDI OW class at the end of the month. I have no certification at all yet. But, I have been around diving my whole life (Dad, brother, and cousins have all been certified forever), done a lot of snorkeling, and did a discovery dive in Maui last year, which felt completely at home to me.
So, I'm anticipating getting my SDI Computer Nitrox cert either at the same time as OW or immediately after. All in prep for some Caribbean diving in December. I've read up on lots of dive sites I hope to visit someday and many of those are deeper than 20m. So, I'm expecting that I will go on to get Advanced and Deep certs.
I currently have snorkeling gear but no SCUBA gear. I'm trying to decide now what I want to buy before going to Mexico in December. If money were no object I would go ahead and get everything except tanks, but that's not in the financial cards right now. So, I'm debating just getting my own computer, for now - ideally, to have it before my OW class, so I can get used to using it then. Additionally, I am very much a "buy once, cry once" (as I read someone say on here) type of person.
After reading up on everything I can find, what I THINK I want is a wristwatch computer with AI and Nitrox support.
And after reading another thread here with similar questions, I already know that there are a number of very experienced tech divers on here who think AI is useless or worse. And I do understand the reasons for those people feeling that way. But, I also understand the reasons some of the AI proponents like them. For me, just doing warm water Rec diving in the near- to mid-term, it seems like a nice convenience. All my info is in one place. Less hoses to fudge with (if it's wireless AI). More detailed info to help me learn about my own SAC. An alarm to alert me if I'm paying too much attention to the pretty fishes and don't notice that my air has gotten too low.
I understand the more experienced divers don't need that. And, on Tech dives, many want to not have it. But, from my one discovery dive, I know I'll be looking at my SPG a lot, for a while. And, at the same time, I don't yet have the habits that come from experience such that I will always remember to check it often enough. So, for my current needs, it seems like AI is a good idea.
---------- Post added September 3rd, 2014 at 03:44 PM ----------
Also, from what I've read and what I believe I will want to do, it seems like having a computer that supports multiple gases is something I will want. But, I have unanswered questions relating to that subject. They include:
- People use hypoxic mixes for more BT on deep dives. But what does "deep dive" mean in this context? Is a hypoxic mix something that one might use in dives to 40m? Or does that only make sense for Tech dives that go beyond Rec limits?
- For dives to 40m or less, it still might make sense to use Nitrox and pure O2 as a deco gas, right? Or does Rec diving simply never involve switching gases during a dive? (and how said is it that I can read as much as I have on SDI and PADI sites and not already know the answer to that?)
- For dives where a gas switch is done, how is that physically accomplished (in a Rec dive scenario if that is applicable)? Do you dive with a 2-tank harness and a manifold connecting the tanks, and have the Nitrox turned on and the O2 turned off, then turn one off and the other on at the first deco stop? Do you have a completely different reg setup on the O2 tank from the Nitrox tank? Do you just use a side mounted pony bottle for the O2, with its own regulator?
- A bunch of the more expensive Rec diving computers say they support multiple gases. But, it looks like you don't enter a dive plan into the computer to tell it when you plan to switch gases. So, if you're relying on the DC to tell you when your NDL time is up, how can it know to allow you extra time because you're going to switch gases? When you program in all your different gases, does it make assumptions about what you're going to use and the order you're going to use them, so that it will reflect your extended BT capability based on all the gases you're carrying?
- And if you have AI, with transmitters for all your gases, does the DC calculate ATR based on all the gases being available? Or just based on the you're currently using?
- If the DC "knows" that you're going to, say, use Air for the first, deepest, part of the dive, then ascend and use Nitrox for a while, then stop and use O2 for deco, does it prompt you to switch gases at the right times? I guess it can't without AI.
From what I've been reading, I just have the feeling that the idea of using a DC to tell you when to head for the surface, on any dive involving more than one gas, is probably just not going to survive meeting the real world.
OTOH, if you assume that dives will always be NDL dives, to a max of 40m, with only one gas, then a PDC with air integration just seems like almost a no-brainer. Especially if you are going to use a DC anyway, and especially if the AI is via hose. I mean, how much would I pay for the cheapest PDC ($200), plus a console with a SPG ($45)? Versus, say, the Oceanic Pro Plus 2.1, which is hose AI (with a compass) and which is $400.
---------- Post added September 3rd, 2014 at 03:45 PM ----------
Okay, so those previous questions were really just for me to get info to understand how I would (or might) use a computer in the future. Now on to the real questions, which are finally getting around to being relevant to this subforum. :-D
- Several people in the other long thread I read suggested to the OP (who was asking about a PDC for Rec use now and Tech use later) advised him to get a Nitrox-capable PDC and use it in Gauge mode. If you're just going to use it in Gauge mode, why does it matter if it's Nitrox-capable?
I expect many of my dives to be after flying somewhere. And I don't have the budget right now to buy a PDC and a full reg set. So, if I am going to fly and rent a regulator (and BCD), then it seems to make sense that I would buy a wrist-mounted PDC. And one with wireless AI means I probably wouldn't use the AI at first (since I don't see installing my transmitter onto a rental 1st stage. But, after I eventually get my own reg set, then I could use the AI, too.
So, I've been boning up on wrist computers that are AI-capable. The least expensive I've found is the Sherwood Amphos Air, which is on sale for $680, with transmitter. And the next most is the Hollis TX-1, for $750, with transmitter. Or $500, without the transmitter.
The TX-1 looks like it has everything I would ever possibly use. It looks like it would be great for Rec diving and using the wireless AI. And, later, if I wanted to use it without the AI, on Tech dives (if I ever go that far), it supports numerous gases, Trimix, hypoxic mixes, Gradient Factors, etc.. Probably way more than I'll ever use. But, the display alone looks like it's worth the extra $70 over the Sherwood Amphos.
I saw many recommendations on here for the SW Petrel. $850 plus shipping means probably $130 more than the TX-1 (which offers free shipping from LP). I like the Petrel display. But, I think I would actually enjoy the wireless AI and the smaller size and wristwatch styling of the TX-1 more. The TX-1 even supports Buhlmann with Gradient Factors, so I think it would actually support any activity that the Petrel would, which means the Petrel offers no real advantage other than the bigger screen - for me, who has no intention of ever diving professionally, though I may eventually pursue some technical certifications just to allow me to do additional fun diving (e.g. deeper, longer, or caves). I do realize you can pay an extra $70 for VPM-B on the Petrel, which I guess the TX-1 doesn't support, nor have a way to upgrade to. But, as I said, I don't expect to dive professionally, so I'm skeptical on ever feeling like I need that. If I get to that point, I can use V-planner and do my own plan and then use any of these just as gauges, right?
I realize all that sounded like I'm just seeking some kind of validation for a decision that I already made, but I'm not. I'm really on the fence about whether to go "whole hog" with something like the TX-1, or just go inexpensive and have an analog console for pressure (and maybe depth and maybe compass). I just HATE the idea of spending even $200 on a PDC, doing OW certfication and one week of diving in Mexico and coming back wishing I had just spent the $750 in the first place.
Further, if I go the inexpensive route, I'm not sure I could really get away with $200 for the PDC. I have compared dive tables (USN, NOAA, PADI, and some others) and done other reading and have concluded that it seems like the PADI RDP is more conservative than the USN tables (I know it's a generalization, just based on a single dive - but I have also compared repetitive dive scenarios). And it seems like all the different PDCs are at least as conservative as the PADI RDP. Some (like Oceanic and Sherwood) being close to the RDP and others, like Suunto, being signifcantly more conservative than the RDP. Plus, reading on here it seems that Suunto is not well-regarded for reliability. Given all that, I think I want a PDC that is the most liberal - since it will still not be any more liberal than the RDP. Which means it uses the DSAT model. Which means, from what I can tell, Oceanic, Sherwood, and Aeris. And I think I want one that shows O2 saturation level, too, not just N2 (since I intend to use Nitrox). So, it looks like I'd have to spend at least $250. Plus, buy a console with a SPG.
I guess what it comes down to is, should I spend $300 for a PDC and a SPG. Or should I go ahead and ante up to $750 for a TX-1 (with a AI transmitter)? Or $500 for the TX-1 w/o TMT? Or should I do something else? Buy a used computer and a $45 SPG? Like I said before, my most pressing goal is to have my own PDC to use during my OW cert and then diving in MX using rental gear. Secondary is not spending money on something I'll want to replace in the next 6 months or 1 year.
And if you actually read all that.... Thank you!!
