larger tanks & back up tanks at 15'

[fernandezh]

Just a little curious,
I have a couple of AL 80' tanks. I was thinking about getting some 100's or 120's. Is the extra bottom time worth the extra weight? Are there any extra hazzards associated with this other than perhaps higher potential for DCS since you have a longer bottom time? I wouldn't think that would be a problem as long as you follow the ascent and deco stop rules.

Another thing is that when I was at the Military Dive school it was standard procedure for the boat captain/divemaster to take the time to strap a tank/regulator at 15' down along the ascent line. I liked this idea because let us say that something happens at the bottom and you are in a deco situation and you blow an O-ring, or inadvertantly run too low on air or whatever problem you may encounter, you can still go and perform your safety stop using the pre-positioned air supply. I haven't seen this type of precaution taken on too many dive boats. The sea fox is about the only one I have seen do this with so far, but I haven't seen it done on a majority of the others. Plus, it is a reminder to divers to perform their stop in case they have a brain fart.



To sum things up:

1. Are the larger tanks worth the extra cost/potential risk?

2. How many other dive boats have you guys seen that take the precaution of pre-positioning a tank/regulator at a safety stop of the ascent line? Is it a norm or is it just that I have been diving on the wrong boats?

[f94gator]

1) Personally, yes, I'd say it's worth it. First off, the weight isn't that big of a deal to adjust to, (unless you get one of those 140 water heater-like monsters). Second, as long as you have a good computer and don't push the limits, you should be able to dive safely regardless of tank size. I'd definitely go nitrox or you're not going to see that much increased bottom time anyway.
2) Haven't been on a charter dive boat in God knows how long, but I can't say that I've seen this as a very common practice at all.

The big tanks are expensive, though. I would love to to eventually switch completely over to hp120's, but that's going to take some time and quite a bit of dough!

[Divin' fool]

I got 7 LP Al 80's and have been thinking about going to the LP Steel 92's. It seems that I am at the edge of deco using 80's at 100fsw anyway. why do I need more air? The main reason for not switching to bigger tanks is the cost. Not only for the new tanks but also for switching my regs to a DIN set up.

[100days-a-year]

Most dives deeper that 100' I wear doubles.LP95s.During the summer I use Al80s or LP95s as singles.Jacked up the 95s can get 110cuft of air .We use an O2 deco bottle at 20' for emergencies or to better flush out nitrogen.I am almost always in deco or close to it unless I get a limit early in the dive.Between me and 2 other buddies we have tanks from 30cuft to 135 cuft and still dive 80s or 95s most of the time .

[joens]

as fer as the hang bottle goes it may be a good idea .especially if you get into deco when you didnt ecpect to. but depending on that tank being there can get you killed.if you are planning on using that tank at your deco stop. then you cant get to it and have to do a free ascent away from the boat.
joens

[Steel Shootin']

I don't see any extra risk due to increased bottom time. You keep your eye on your computer to make sure you don't have mandatory decompression stops.

IMO, HP 120s are the way to go. For one thing, they don't weigh that much more than AL 80s. That's one of the things that surprises people the first time they pick-up an HP 120. The extra air is great, and I frequently get two dives off one tank, even in the Middle Grounds. I would never go back to AL 80s, or even HP 100s. The HP 120s are a perfect fit for the type of spearing we do.

[f94gator]

Originally posted by Divin' fool
I got 7 LP Al 80's and have been thinking about going to the LP Steel 92's. It seems that I am at the edge of deco using 80's at 100fsw anyway. why do I need more air? The main reason for not switching to bigger tanks is the cost. Not only for the new tanks but also for switching my regs to a DIN set up.

I agree with that. Deco and low air always seem to hit at the same time on 80's - when using regular air. If you go to nitrox, you get far more bottom time and the bigger tank makes much more sense. You can stay down a good bit longer and not be tempted to push the table limits for a few extra minutes.

Cost IS an issue that you're not going to get around. You might be able to find some deals, but for now the hp120's simply don't come cheap. A new reg isn't cheap, but at least in my case I needed a new reg anyway so I just got a DIN with a yoke adaptor.

[poorshot]

Hey Fernandezh,

What book did the verse at the end of your post come from?

[Divin' fool]

I like that quote too.... I can just visualize one of those rag heads getting their due:mad: .... it won't be too long now:eek:

[richhermes]

it's from Pulp Fiction--Samuel L. Jackson said it.

[100days-a-year]

That was the verse made famous by Samuel L Jackson in Pulp Fiction.Just before they shot the place up.

[fernandezh]

Rich was the first one to have it right, it was Samuel Jackson who said it in Pulp fiction. It is a combination of several verses from the book of Ezekial but for the most part it is Ezekial 25:17. It is something I memorized to get the adrenalin flowing whenever something big comes up at work. Believe it or not, underwater it is something that I say to myself when I see a bull shark in the vicinity. So far I have not been eaten so it must work. Every little bit counts. :-)

I personally like it when I am on a boat and see the divemaster/captain take the time to put out a hang bottle as an extra precaution. Every reasonable precaution should be taken when somebody's life and safety is on the line. Of course, nobody should rely on a "back-up" to save their tails and intentionally go into a dive table violation counting that they will make it back to the ascent line and the back-up (hang bottle) be there. Anybody who does this increases their chances of removing themselves from the gene pool, and proving Darwin right.

[rusty]

Go for the bigger tanks. It's easier to get a good fill with the low pressure steel. I have a LP 108 that's great (good fill = 145cf), 8" diameter will not fit in some boat racks. Also have a pair of HP 120's, and a single AL80. The steel tanks are all Nitrox. I was able to buy a DIN kit for my Apeks reg. on ebay for $20, and purchased a Yoke adapter (for the LP and AL tanks) for about the same price.

The LP108 is heavy when full before the dive, but you don't notice it in the water, except for the extra air.

The extra bottom time is worth it, and if you don't use much air, use it again.

[kitefisherman]

Steel tanks with nitrox is the way to go. The extra weight of the tank is at least partially offset by having to carry less lead. I carry 16 pounds with an AL80 and 8 pounds diving steel. I really don't notice a difference in weight, especially underwater.

I have an AquaAire pressed steel HP 120 and an OMS LP 98. The 98 is rated at 2400 PSI, but I've never had a problem getting it pumped to 3000 PSI giving me 25% more than the 98. So both tanks have approximately the same air with the HP at 3500 PSI and the LP at 3000 PSI.

My LP has an OMS modular valve. The valve is a DIN but comes with a screw in insert that converts it to a yoke if you want. I usually dive DIN but it's a nice option if you need to use a back up reg that is not DIN or loan it to a buddy who doesn't have a DIN reg.

The LP cost about $400, and the HP about $320. I like my LP better and better every day and think it's worth it. For one thing, the OMS LPs have a design life of 10,000 cycles at 4000 PSI. If you pump it to 3600 PSI you will have approximately 150 CFT (a HP 120 pumped up to 4000 PSI will have 137 CFT). I also understand that my LP may be more durable than a HP that is made with spun steel that has a higher o2 content making it more susceptible to rust. My HP is made with pressed steel; however, when I took it in for its first VIP, I had to have it tumbled and that cost around $30. The OMS LPs have food grade metal oxide lining the interior of the tank so that they are less susceptible to rust.

I have no complaints, but if I had to do it all over again, I'd probably go with 2 OMS LP 108s or a 108 LP and a 121 LP. The OMS LPs all sell for about $400 regardless of size (66, 85, 98, 108, 121 or 135 CFT). You might as well have the extra air without the need to pump the tank so much.

[fizisition]

glad to hear this positive lp talk Iv'e been looking at the pst lp's for a while now but all this hp hype was making me reconsider
so screw it maybe I'll just go drop700right now hell it's only money:D

[fishhunta]

i like pressed steel tanks- as they do make the best high pressure tanks, but for low pressure tanks, id stick with faber (scubapro, OMS, faber). they definately have the best track record.
another positive for lp is that gasses blend better at lower pressure. that is important for nitrox, but especially important for trimix where you have helium which is an extemely light, compressable gas. the lower pressure tanks are more corrosion resistant not only because of the lining, but also because nitrox, at a lower psi, has a lower p02 inside the tank. the higher the p02, the more susseptable the tank is to oxidation, thus making the lp less susseptable. my .02
BTW- I'm the one who convinced Kitefisherman to get his faber lp

[Charlestondivin]

I love my faber lp 108's.
http://www.divesales.com has them for $252.
Cheapest price i found when i was looking. Lds says this guy is selling em cheaper than he can buy them.

Thought i would pass that on.

[fizisition]

[QUOTE]Originally posted by fishhunta
[B]i like pressed steel tanks- as they do make the best high pressure tanks, but for low pressure tanks, id stick with faber (scubapro, OMS, faber). they definately have the best track record.
hunta!
did you hear something bad about pst lp ?
I chose pst because they were - when empty
the fabers were +4.5 I read

[kitefisherman]

Charlstondivin: Great prices even with the shipping. Thanks.

Fizisition: Empty OMS tanks are generally neutral to a pound or so negatively bouyant. It varies by tank size http://www.omsdive.com/cyl_spec.html

[fernandezh]

Originally posted by Charlestondivin
I love my faber lp 108's.
http://www.divesales.com has them for $252.
Cheapest price i found when i was looking. Lds says this guy is selling em cheaper than he can buy them.

Thought i would pass that on.

Guys,
I appreciate the input. Charleston, I think I am going to go with your recommendation. The 108's have the balance between size and price, that I am looking for. I am definitely going to use them for NITROX. if anybody else has anything else to add, I would love to hear it. I am willing to entertain all suggestions.


Hector

[sbreland]

I've used Pressed Steel 95's as singles for the last 6 years. They are hot dipped galvanized for corrosion protection. I have a Faber (OMS labeled) steel 66 that my wife uses, also. The only issue I have with the Faber tanks is they are painted. This means nothing to the diver except you must be careful to rinse thoroughly including under the boot. The finish was eaten off of the Faber 66 in the area under the boot in about 18 months. Luckily my LDS owner caught it at vis time. He repainted it and all is well. My next steel tanks will probably be Fabers mainly because the Pressed Steel 95's are about 9 pounds heavier than the Faber 95's. I believe, based on nothing scientific, that the Pressed Steel tanks are the more durable, but both brands are so far ahead of AL 80's in every way that it is a toss-up. Diver's Supply commonly carries Faber 95's for about $250 complete.
I find that I run out of time before I run out of air with the 95's.

[fernandezh]

Originally posted by sbreland

I find that I run out of time before I run out of air with the 95's.

Is that running on air or NITROX?

[sbreland]

I was referring to air. I do dive nitrox when it is available and appropriate (not for a 32 foot Cooper River dive, for example) and the bigger tanks are the cat's pajamas for nitrox, too. With nitrox the time and air relationships are similar to using air with an AL80. That is, your time is extended but so is your air supply.
Just to add to the confusion another thought might be an AL100. Some people don't like them but then again I know several folks who say they are just fine. A bit less expensive than a similar sized steel tank. Two drawbacks, though: they require a vis+ and must be pumped to 3300 psi. A plus for AL tanks is that you can bet you'll have trouble with an air fill station over getting your steel LP's pumped to the 10% overfill. Every teenage attendant can be made to understand what a 3300 psi AL100 requires since it says so on the tank.
One last issue: getting a +hydro done on a steel tank after the original expires can be a real pain. If you don't get the + then all you have is a heavy 85 cf 2450 psi tank. Might be worth checking into if you plan to keep your tanks more than 5 years.
I got mine +hydro'd, but it was a hassle.

[mlex]

run charters on the "Bubble Watcher" (27' Lindsey) out of Murrells Inlet, SC. ledges and bottom structure out 32+ miles in 95'+. O2 on board, hang a al80 @ 15' amidships & a pony "bail bottle" at anchor. have a group of usual suspects we know and rely on not tohave brain farts, butttt..................

[Steel Shootin']

Nooooooooo!, do not get LP tanks!! Pressed Steel HP 120s is the only way to go. If you go LP, your tanks won't fit in anyone's tank holders (e.g., pelican racks, brackets, etc.), and you'll notice that no one wants to help you move them (and when they do, it will be accompanied with comments like, "Who the f___ brought the &^#$@ low pressure tanks?") :D

[Screen Name]

I really like my HP 120's. For those that are studying this, do a search on "tank poll" for some prior discussion.

For me, the bottom line is, both the HP and LP tanks give you about the same volume......an HP 120 has always yielded more air than I could use, so why would I want a bigger tank that doesn't fit anybody's rack?:cool:

[100days-a-year]

'cause a jacked up lp holds a lot of air and allows you to wear less lead.And besides I need the exercise .It also keeps sissies from snagging the wrong tank.They are also easier to get filled while travelling.The average tank monkey fills everything to 3000-3200,good for lp bad for hp .In the keys we drop off 10-20 tanks at a time tip the monkey or give'm a 6pack and come back to lovely fills.Other than that they suck.

[seahunt]

1-How readily can you change from din to yoke on the Hp?

2-Any drawbacks on using the adapter?

Seen the hp's and will love to try one.

[f94gator]

Originally posted by seahunt
1-How readily can you change from din to yoke on the Hp?

2-Any drawbacks on using the adapter?

1-Pretty damn easy. Adaptor screws right on to a DIN reg. Bam, you're done.

2- The 1st stage might be slightly bulkier, but nothing that really bothers you.

[Divin' fool]

All it takes is an adapter attached at the DIN valve and you can use the regular 1st stage? I always thought you had to change the attachment on your 1st stage.

[kitefisherman]

You guys are talking about two different things:

1. Using a yoke regulator with a convertible DIN valve: You have to have a convertible valve. It's a DIN with shallower threading inside into which the adapter threads. It you use the adapter on a standard DIN, it won't work because the adapter will screw too far in.

2. Using a DIN regulator with a yoke valve: You screw a yoke adapter on to the threads of your DIN 1st stage and attach the adapter to your tank.

[Steel Shootin']

Originally posted by 100days-a-year
It also keeps sissies from snagging the wrong tank.... If it makes you feel tougher to strap on an LP, then have a ball with them. :rolleyes: Personally, I don't see the logic in buying a product that was intended for low pressure, modifying said product (burst valve) in order to RAM high pressure into it, so that your tank can weigh 30% more than a tank that was designed for higer pressure in the first place, and fit no place in the boat so that it has to be strapped somewhere that will be in everyone's way.

[f94gator]

Preach on!!!!!!

To each his own. All I know is my first time with an hp120, I was like, "MAN, where have YOU been all my life!!"
Personally, I won't be buying any lp tanks unless they're being given away. Hp all the way.

[kitefisherman]

I have a HP 120 and a LP 98. The HP is cranked to 3900 PSI and has about 134 CFT of gas. The LP is cranked to 3800 PSI and has about 155 CFT of gas. I just weighed both tanks on the same scale and they both weighed 50 pounds.

[100days-a-year]

Scott,LPs were designed for 3500service pressure x10,000cycles.The DOT is responsible for the 2400+ .European tanks aren't required to have and seldom have burst discs.My factory discs were 4000psi,I left them in .See kitefishermens post about actual weights.An AL100 is heavier than my tank as well.Also taller.An HP120 is taller as well .One of those other places like divernet or echhh....rodales will have the comparitive weights of most tanks.The sissies comment was a jab.

[kitefisherman]

What brand LPs are you using? My OMS 2400 PSI LPs have a design life of 10,000 cycles at 4000 (not 3500) PSI. They also have a minimum burst pressure of 6400 psi. I assumed that they were all the same.

[Steel Shootin']

I'm just giving you guys a hard time. Some guys love those LPs. Those 104s feel a lot heavier than 120s, but if your comparing the volume of air, then maybe it makes sense. To each his own. :D

[100days-a-year]

Kitefisherman,that was from a Faber quote somewhere.Since they make OMS I assume your # may be right.I have both.Minimum burst pressure is the cylinder not the discs.I've had people(idiots) leave a borrowed tank in thier car and have discs pop.To get a real good lesson in tank abuse hand out with old cavers.I see really hot fills and 50yr old stage bottles full of O2 every weekend.One buddy has a tri-mix station in his garage and another bought a 17cfmBauer for his autobody shop;).One won't fill an Al past it's rate but'll fill lp to 3900.The other will fill Al80 to 3900 but hated diving around me n' buddy #1 cause we dove steel.It's like Scott said......whatever floatsa' ya boata'.Bottom line is bottom time!

[Charlestondivin]

http://www.huronscuba.com/gear/cylinders.htm
This is a chart that contains Lenghts, weights, bouyancy, etc. Good tank info.

[rusty]

I know some boats have a problem with them, but I like having 140-150cf (at 3500) in the LP108, vs the 120 in my HP120. And as other people have stated, if you are only able to get a 3000-3200 fill, the LP is an advantage.

my $.01