Dive Computers: Useful Tool or Overpriced Toy?

Almost every recreational diver is familiar with dive computers. Diver-carried computers have become a way of life. The question is: do dive computers have a role in technical diving?

First of all, let me define the scope of this discussion so we’re all on the same page. Let’s limit our discussion to diver-carried computers designed for technical diving. These computers are capable of tracking multiple gasses and computing a decompression schedule. Within this group of dive computers, we can further divide them into computers that are capable of calculating deco schedules for helium-based mixes (“trimix” computers) and those that only deal with mixes containing oxygen and nitrogen (“nitrox” computers). The Liquivision X1, Dive Rite Nitek X and Delta P’s VR3 are examples of so-called “trimix computers” while Dive Rite’s Nitek Duo and Trio are examples of multigas “nitrox” computers.

Next, let me dismiss the idea of using recreational dive computers (i.e. single gas, no decompression) in a technical diving setting (i.e. multiple gasses including trimix and staged decompression). Trying to do this is like using a hammer to drive in a screw: it’s simply the wrong tool for the job.

I am also not going to discuss specific brands and models, nor am I going to attempt to provide some sort of “Buyer’s Guide.” I’m going to discuss the general debate centering on technical dive computers vs. tables and bottom timers.

Historical Perspective

Technical dives are complex and require lots of planning. You have to choose your bottom gas, deco gas(ses), calculate a decompression schedule, calculate the volume of each gas required and factor in contingency plans. Historically, divers have used computer programs on a desktop computer to run various scenarios and come up with the most viable plan for a given set of dive parameters. The software generates a deco schedule which is transferred to a slate or waterproof notebook. During the dive, the diver uses a simple timer and depth gauge to follow the plan.

Since the advent of dive computers specifically designed for technical diving, the debate has raged between the “computer” crowd and the “bottom timer and tables” camp. The computer devotees cite the main advantages of wearing a computer as flexibility (i.e. endless contingency plans on my wrist), accuracy (the computer is calculating deco based on actual depth/time rather than pre-cut tables of what I think depth/time will be) and elimination of human error. The bottom timer advocates cite economy (“I can buy a lot of bottom timers for the cost of one computer”), lack of necessity (tables work fine, why change?) and the notion that a dive computer will become a crutch for divers. Both sides make valid points. Let’s look at a few of these points.

Flexibility Computers do offer great flexibility. If your depth or bottom time should deviate from the planned time or depth, the computer will modify the deco schedule to reflect such variances. If a planned deco gas is not available for some reason, the computer will again modify the deco schedule to account for the loss of this gas. BUT, argue the computer opponents, if you really understand deco theory, you should be able to calculate those kinds of table “tweaks” yourself underwater using only the dive computer between you ears. This leads into the next argument against using computers.

Computers are nothing more than crutches for inept divers. Some argue that if you understand decompression theory and how to apply it, you can generate a reasonable deco schedule off the top of your head, or, as in the example above, modify an existing schedule to account for changes in the dive plan. I think this premise takes a sound concept and takes it to absurd proportions. I do agree that all technical divers should thoroughly understand decompression theory and its application. I believe it is imperative to have a solid foundation in deco theory before one can intelligently use a dive computer. I can’t imagine any instructor advocating that students buy computers in order to avoid learning decompression theory. Remember, a dive computer is a tool. Tools are stupid; they rely on the craftsman to have the skill to use them properly.

Accuracy Proponents of dive computers point out that computers provide a more accurate depiction of the actual dive. Most technical divers using desktop software plan a dive as a square profile, that is, the diver descends to maximum depth, remains there for the entire bottom time, and then begins a direct ascent to the surface. In reality, the depths of the dive may vary during the dive and the square profile may generate an unnecessarily long deco schedule. The computer, however, is constantly calculating and re-calculating the deco schedule based on current dive parameters.

No discussion of dive computers would be complete without mentioning cost. There’s no denying the fact that computers for technical diving are expensive. While a multi-gas nitrox computer may only cost several hundred dollars, a sophisticated multi-gas trimix computer will set you back over one thousand dollars, with some close to two thousand. Are dive computers worth the expense? That’s a personal decision each diver must make for him/herself.

Conclusion

Whichever tool you decide to use to manage decompression planning, it must be a team decision. Team members must communicate and agree on procedures for the dive. All members of the dive team must use the same gasses, follow the same profile and use the same decompression planning tools.

No matter what dive computer or desktop software package you use, you should:

• Understand decompression theory and its application
• Know how the software you are using functions and use it only within its stated parameters
• Consult with dive team members when planning dives so you are all on the same page
• Use decompression planning tools conservatively
• Dive within the capabilities, limitations and certification levels of the least experienced team member

In technical diving, there should be no egos within the team. You should be absolutely comfortable talking with and asking questions of your teammates. After all, you are placing your life in their hands and they are doing likewise.

Choosing a Technical Diving Instructor

Technical diving is a risky venture. Let’s have no illusions about it, scuba diving, especially technical diving, can kill you. So choosing the person who is going to train you in this risky endeavor should not be taken lightly. When I began the process of becoming a technical diving, I was lucky enough to get some very good advice from others who had gone down this road before me. I’d like to share that advice and also describe my own philosophy towards technical diver training.

Choose an instructor who is doing the kinds of dives you would like to do. If you want to do deep trimix dives on wrecks like the Gunilda, then choose an instructor who is doing dives like that. If your aspiration is to dive deep wrecks in the Great Lakes, then choosing an instructor who primarily dives only in the Caribbean, or on training dives with students in a quarry, probably isn’t going to give you the best results.

Avoid instructors who only dive when teaching. Instructors are divers too. We need time to do our own “fun” dives in order to grow personally and professionally. Instructors who only dive with students on training dives are not challenging themselves, which leads to stagnation.

Train in the environment in which you want to dive. Don’t do your coursework diving in warm, clear tropic waters if your goal is to dive wrecks in the Great Lakes. If you’re going to dive wrecks in the Great Lakes, train in the Great Lakes. If your goal is to only dive wrecks in tropic conditions, then train in tropic conditions.

Don’t confuse price with value. The first question you ask an instructor should not be “How much does it cost?” Get to know the instructor a little bit before getting to price. Find out the instructor’s views about training and diving in general. Find out details about the course like what topics are covered, how many dives are conducted, are the dives conducted only in quarries or are there charter dives too, and how many students will be in the class. When you do get around to price, you’ll have a better idea of whether you’re getting a good deal or not. Sometimes a more expensive course is a better value because it includes things that cheaper courses do not.

Ask lots of questions. Basically this a job interview for the instructor. Ask the instructor about his/her personal diving. What type of diving does he/she like to do when not teaching? What are the equipment requirements? Tell him/her about your diving experience and what you hope to learn in the course. Explain your diving goals. Look for a personal connection. Do you like this instructor? Do you trust him/her? At this level of training, a good rapport is essential. You may find a perfectly competent instructor, but you may decide not to take the course with him/her if you detect a personality mismatch.

I try to incorporate the above points into my own teaching ethic.

• I actually train only a handful of divers each year. This allows me about half of the dive season for my own personal diving. I’m learning new things about diving all the time. Having an instructor card doesn’t mean I know everything there is to know.
• I offer courses exclusively in the Great Lakes area. I cater to Great Lakes divers who want to extend their diving capabilities in order to visit deeper, more pristine wrecks.
• I strive to price my courses fairly and to make them valuable by adding things other instructors may not. My students begin course dives in the quarry and then progress to actual Great Lakes dives. I don’t award a technical diving certification based solely on quarry dives. Class size is kept small and scheduling is flexible. Students know the total cost of the course before we begin. I make clear up front what the course fee covers and what it does not cover. There are no hidden fees.

Technical diving is not for everyone. It is risky and potentially fatal. If you decide to take the technical diving path, choose your instructor carefully. This choice will affect the rest of your technical diving career.

What do you want to do this summer?

I haven't posted anything here for quite some time, mainly because it's winter and the water around here is solid, hence no diving for me, so no posts. As we enter the coldest, bleakest month of the winter season, my thoughts are split between remembering the past dive season and planning for the upcoming season.

Last year was a pretty dismal season for the dive industry I think. The economy was bad and that hurt, especially around here, the heart of the American auto industry. Course enrollments were down, charter trips weren't running full and overall interest in technical diving was virtually non-existent.

So I'm curious, what do you folks envision yourselves doing, diving-wise, in the summer of 2010? I ask for two reasons: idle curiosity and business planning. I'm just plain curious what people want to do. Are you interested in diving any particular wrecks? Do you plan to further your dive education? I'm also interested in feedback so I can integrate it into my upcoming course and trip offerings.

So please, feel free to post what kind of diving activities you're thinking of for this season, or post if you're not going to dive at all. Thanks.

2010 Class Schedule

I know it's not even Christmas yet, but I'm already plotting out next year. I have some tentative dates for courses set up, but naturally if you want to take a course on a different date, let me know and we'll work something out. I'll get the dates up on my website tomorrow, but those of you who follow the blog get a sneak preview.

• Saturday March 27, Gas Blender (Wauseon, OH)
  
• Sunday April 25, Gas Blender (Wauseon, OH)
  
• May 22-23, Intro to Tech (White Star Quarry, Gibsonburg, OH)
• June 26-27, Advanced Nitrox/Deco Procedures, further dates TBD, (Gilboa Quarry, near Findlay, OH)
• July 2, 3, 4, Trimix Diver, (Gilboa Quarry, near Findlay, OH) completion dives will be July 22-25 in Presque Isle, MI
  
• Aug. 7-8, Intro to Tech (White Star Quarry, Gibsonburg, OH)
• Aug. 10-13 I'll be in the 1000 Islands. All courses are possible including Adv. Nitrox/Deco, Advanced Wreck Diver, Trimix Diver.

E-mail me if you are interested, would like more information about classes or have questions. If you know of anyone else interested, please feel free to forward this info to them.

Risk Assessment, A Call for Action

There seems to have been a handful of diving fatalities lately. I guess accidents are inevitable. There have always been a few diving accidents per year, however it seems in recent years the people involved has changed. It used to be most accidents in the technical diving/cave diving realm involved divers untrained for these "extreme" activities. Lately, it seems that more and more fatalities involve highly trained divers (i.e. divers who should know better) putting themselves at risk by violating basic procedures that have stood the test of time.

At the recent NACD conference, Steve Lewis (TDI/SDI HQ staff, Instructor Trainer, Technical Diving Instructor and all around man about town) presented his thoughts on risk assessment/management, cave training vs. wreck training, and related issues.

Here is a link to the text of his presentation. Please read it and please be careful when diving. Follow your training and don't cut corners. To paraphrase Larry Green, NACD Training Director, "Develop solid safety protoccols and have the discipline to follow them on every dive."

Cave Diving Conference & Trip Report, Nov. 2009

I just returned from five days in north Florida where I attended/presented at the National Association for Cave Diving's (NACD) 41st Conference. After the conference, Marshall Allan and I hung around for a few days of cave diving.

We arrived in High Springs, FL on Friday Nov. 20. After checking into our motel, the very nice Rustic Inn (which actually isn't that rustic), we headed over to Ginnie Springs for the Friday Night Social that the NACD has each year the night before the conference. It was a very nice affair, with free food, free beer and a Chili Cook-Off. We had a good time seeing old friends and meeting some new ones. We called it a night early since I had to do a presentation at the conference the next day and preferred to do it without a hangover.

Saturday morning, we drove to Gainesville for the conference. This was my first time to the NACD conference and I was impressed. There were probably 15 or so exhibitors displaying their wares in addition to the presentations that ran from 9-5. I won't go into detail about all the presentations, but my favorite was Becky Kagan's video of Weeki Wachee Springs. I wouldn't be surprised to see an expanded version of it air on Discovery Channel or some other entity. Other presentations covered training and safety issues in cave diving, updates on various surveys and explorations and some joker from up north talking about cold water wreck diving. Oh wait, that was me. I talked about Great Lakes wreck diving and showed some footage of the North Wind, one of the best wrecks in the Great Lakes (that I've seen anyway). The gist of my talk was about overhead diving in cold water/limited vis. When I was invited to give the speech, I honestly couldn't figure out why a bunch of cave divers wanted to hear about wreck diving. The presentation went pretty well. If they fell asleep, they were at least polite enough not to snore! Much to my surprise (and delight), a couple people actually found me after the show and told me they enjoyed my talk, had no idea Great Lakes wrecks were so well preserved, but we're nuts anyway to dive in that cold water.

That evening, we were invited to Larry and Debra Green's house for drinks and to shoot the breeze. Larry is a true diving pioneer and it was amazing to just sit back and listen to his stories and marvel at the history he lived through. This guy was experimenting with trimix in the Eagles Nest cave system back in 1989! As the evening progressed and the stories flowed, it became obvious Larry has forgotten more about cave diving than I'll ever know.

Sunday morning was rainy and chilly. About noon, the weather started to clear, so Marshall and I headed up to Peacock Springs for a couple dives. We did two, one hour dives there. It was a good way to reacquaint ourselves with cave diving since we hadn't been in a cave in about a year. We headed back towards High Springs, stopping by Amigo's to fill our tanks on the way.

Monday we got an earlier start. We stopped by Alice's Parkside Restaurant for breakfast, and then headed to Madison Blue, a cave system we had not dived before. Other than the park ranger and a couple of her friends, we were the only ones there. The spring is probably about 60 feet in diameter and very clear. We could easily see the cave entrance at the bottom of the pool. We geared up and jumped in. After our S-drill, into the cave we went. The flow wasn't as bad as we expected, so entering was easy. The cavern area is fairly large and interesting to dive in it's own right. To enter the actual cave passage, we dropped down a crack into a relatively low passage. The low part only last the first few hundred feet and then it opens up a bit. It's quite a nice dive and even though the flow isn't all that bad, it only took us 15 minutes to exit the cave, after spending 35 minutes swimming in. On our second dive, we went in about 500 feet and then jumped off to a side tunnel. We think it might have been the tunnel to the Banana Room. After our dives, it was back to Amigo's for gas fills. Then dinner at the Fleetwood Diner where I had the meatloaf platter. I'm a pretty good eater, but even I couldn't finish the two huge slabs of meatloaf and pile of mashed potatoes.

Tuesday was departure day. We cleared out of the Rustic Inn, packed the car, and headed back to Madison for one last dive. After all, it was right on our way home. We did one dive, an hour long, and just stayed on the main line. It was loads of fun. There's a lot to be said for diving in warm, clear water with no waves. If only Florida and Ohio were a few hours closer. Anyhow, we packed the car and started the trek home. We made good time (except around Atlanta of course). We felt pretty good and not a bit tired, so drove on and on. By the time we started to think about calling it a night, we were crossing in to Kentucky, so we said what the hell, let's keep going. So while one of us slept, the other was awake. We just had to make sure the awake guy was driving and the sleeping guy was in the passenger seat. We pulled into my driveway at 5 am Wednesday morning.

It was a great trip and I loved seeing some old friends and doing some cave dives again. I need to get down there on a more regular basis and not wait another year and a half like I did last time.

2010 Dive Trips

Fall is in the air and the 2009 dive season is about over. That means it's time to plan for next year! I currently have two Great Lakes wreck diving trips planned for next year (more to follow).

On July 10-11, 2010, I'm going up to Harbor Beach, MI for a very special trip. I have booked the morning charter both days with Rec and Tec Dive Charters and my good friend Capt. Gary Venet. We're going to try to get to the seldom-dived stern section of the Daniel J. Morrell. The Morrell was a 586 ft. steamer. In November 1966, the Morrell was upbound on Lake Huron in a horrible storm. Near the tip of Michigan's thumb, she broke in half. The bow section sank as the stern, still under power, steamed another 5 miles until it sank. Due to it's distance from shore and the uncertainty of the weather, neither of the sections of the Morrell are visited a lot, and when people do get out, they usually do the bow section. Our other objective for the weekend is the newly-discovered Charles A. King. Gary tells me the King is an upright, intact schooner. He and his colleagues discovered her several years ago and have been diving her to identify and document her. 2010 will be the first year Gary will be running charters to her. Be among the first of the diving public to see her.

On July 22-25, 2010, I'll be diving Lake Huron near Presque Isle, MI. I used to dive that area 2 or 3 times per summer until about 2005. Last I led a trip there and fell in love with the area all over again. To read the trip report, which includes descriptions of the wrecks, look here.

Trimix certification is required for both trips, as depths of the wrecks range from 165'-200'. Obviously the target wrecks may change due to weather. Contact me at rick@GreatLakesTechDiving.com for more info and keep an eye on my website, www.GreatLakesTechDiving.com for more trips.