I'll anger a few but Brownie's, if you use two divers, both divers work off the same outlet line. If that fails both divers are in deep doo doo. Don't know if Keene has upgrades but they used to be belt drive. The belt breaks, and they do, you have a spare or you are done diving. The best, the Cadillac with the best compressor is the Airline by J Sink. http://www.airlinebyjsink.com/ The university of Florida once used them for the marine studies unit. Don't know if they do anymore. Parts for the Thomas compressor on the Sink can be had anywhere in the world and they are easy to rebuild. If you life depends on your equipment I'd get the best. IMHO Brownie's and Keen come in a distant 2nd and 3rd in comparison to the sink unit.
All the above use gasoline engines of some kind. Mine had a Honda on it and Honda's are quiet, correct? The compressor itself is noisy and add that even to a quiet engine like the Honda and you have just irritated every person on the beach and any homeowners near your dive site. It even makes it fairly hard to hear you underwater detector. The noise and vibration travels down the hose into the water. What if the engine quits? Not an issue even if you don't have a reservoir tank with your unit. You'll know instantly when the engine quits and you have about two good breaths of residual air in the hose line. If you are working deep and don't have a Pony bottle, you are stupid.
I was tired of the noise of the gas set up. It's great because you can run for hours on a couple quarts of fuel. The engine and compressor are fairly light and mine floated inside a truck tube that held everything including the dive flag. But the noise it made trumped it all. I went to the Hookamax DC unit. They used to have a picture on mine on their site but I didn't search the site when I got this URL. http://www.hookamax.com/17710.html?*session*id*key*=*session*id*val*
Here's the problem with the DC unit. It takes big heavy batteries to power it. A battery big enough to supply two divers to 30' for 3 hours weighs about 125 lbs. I cheated a little. I got two 6 volt deep cycle golf cart batteries and hooked them in series. It still runs 3 hours on a charge, actually more i just got tired after that long, and each battery weighs 62 lbs. This unit has a reserve tank. When the demand for air is relatively low and the pressure in the tank gets up to 80 PSI the compressor shuts off. When the air is drained, by the diver breathing, and gets to about 70 PSI, the motor kicks on again. Many times I surfaced to check what was going on around the topside and the compressor was not running. I bought a big heavy duty beach wagon and mounted all my stuff on that. It holds both batteries, the compressor, and the hose lines I put on reels. All I need do is pull it to the beach where I am going to dive.
Now your initial question was not a review of the various hookahs on the market, it was a comparison of tanks vs hookah. Tanks are heavy to carry and you have to pay to get them refilled. You have to pay for a visual inspection every year and every 5 years they have to be hydrostatically tested to ensure they are safe to hold the pressure that's put into them. The dive shops look at both the hydro date and the inspection sticker before they fill the tank. If they are not current, no fill. However, you put the tank on and head out and you can go wherever you want. There's no down line providing your air supply. The encroaching boat will not run over your airline and raise heck with your dive.
Generally, the hookah set up is nice because you don't have that darn tank on your back. You dive can last as long as your batteries or gasoline supply and if you got lost in zero visibility you can grab your airline and follow it to the surface, if you just don't want to come up where ever you happen to be. There is a tendency for those air lines to act like an angry snake and not go where you want them to go. They can get caught on stuff easier than when using a tank. If you go with Hookah get the 100' lines, not the 50's. Some areas you want to hunt, even with the Hookah in the middle of the beach, if you leave it on land, a 100' radius from air source is not really as big as you might think.
To answer your question directly I can tell you I have a Hookamax 3/4 HP DC electric unit that can support one diver to 50' or two divers to 30'. I also have two SCUBA tanks set up and ready to go with bouyancy compensator, octopus regulator set up, etc. I choose the correct equipment for the site I am diving. I have limited myself to two tanks as I am an old fart, and a single tank will last me about 1.5 hours in shallow water. Even with a dry suit, after 3 hours of dive time whether Hookah or SCUBA, I am done for the day. jim
I forgot to add...Diving with a hookah and no training is just as dumb as diving with SCUBA with no training. Get the training. It's fun. The instructors want you to succeed and will do everything they can to get you safely through the course. No training and someday somebody will read about the tragic loss of a local metal detecting diver. Blunt...but highly probable outcome without training.
