Doubts about tanks for wreck penetration

[rjack321]

I wouldn't dive smallish doubles (lp72 up to hp100s) or even hp130s without nitrox. You'd have scadds of gas and almost no bottom time to use it in.

For instance on the U 353 at 115' you'd have roughly 10-12 mins of no deco and use 25 cf. So while I would not advocate doing this dive on an AL80, if you were diving air you basically could dive it on a tiny tank. A lp95 or a hp100 would be fine IMO if you were limited to air.

There's no way air would give you enough time to do penetration at these kinds of depths.

I would take a nitrox class before buying big singles or doubles. The classes are all pretty similar, its the instructor which really makes a difference. So see if you can take one through a tech instructor if possible. It would give you a low-stress window on their teaching style. Allowing you to 'try them out' if you will.

 

[jim T.]

Yes, that's a very valid point. rjack. Thanks. I'll let you know what develops.

 

[MonkSeal]

I had forgotten that the bottom was only 115'. I've done three 105' dives on British Columbia, Canada wrecks on air (no narcosis symptoms) but will likely do nitrox training very soon now that I'm all inspired.

Diving nitrox doesn't mean lower level of narcosis. If you want do decrease narcosis at above mentioned depths the gas of choice is triox 30/30.

 

[azcaddman]

We were in NC sept 28-30, and did 2 dives on the u-352, temp was in the 78-79° range, 3mm was plenty.

Tanks used were LP95's, filled to 2800, 30% nitrox, had plenty of gas for 25-30 min bottom times, of course this incured a short deco obligation, but we still returned to boat with 900-1000# still in tank.

I entered the wreck at the forward torpedo loading hatch, and don't think I would have fit with doubles, of any size, but then I'm not exactly skinny. I would not recomend going into this wreck without proper training.

We also went into the Papoose (hutton), it's much more open

Visibility was in the 30-40' range, as a tropical storm had passed by the previous week.

more photos on my website at this address

 

[rjack321]

No reel?

 

[azcaddman]

no reel, just (2) 150' spools, each.

 

[DIR-Atlanta]

no reel, just (2) 150' spools, each.

A DIR diver should always carry a spool. I think the question was asked to try and determine if you did the wreck penetration without using a primary reel.

 

[azcaddman]

to clarify, we did not take a primary reel, as the penetration was to be of relativly short distances.

we did take a safety spool (each) and a 2nd spool for navigating the wreck(s) (each), as we felt that 150' (or 300, if we just tied one into the other) would be sufficient.

 

[TSandM]

I think you can take basic Nitrox from almost anybody. There is really not that much to the class. Some simple algebra and some basic physiology/toxicology information about oxygen, and you can almost self-teach it.

I absolutely agree that training is probably more valuable than equipment in progressing to more involved diving. As everybody on this board knows, I'm a big fan of Fundies or Essentials as a path to better buoyancy control and stronger diving skills in general. Joe Talavera and Steve White are excellent instructors (although quite different) and both have a really superb curriculum.

I've told you already that I'm diving doubled 72s -- They aren't enough gas for a real human being to do two dives on, but they've been quite manageable from a weight standpoint (even if Blitz says I can't schlep my own gear, just because I didn't want to pick it up off the ground ) Peter's HP 100s are very little different in weight, and if I decide I'm diving doubles enough to make it worth while, I'll definitely borrow a set of those to try before I buy anything.

Jim, you just need to come down and spend a few days in Seattle and hook up with some folks who can lend you various pieces of gear to try out. No point in shelling out a lot of money when you have the opportunity to try things and KNOW you're buying the right stuff.

 

[dsteding]

I've told you already that I'm diving doubled 72s -- They aren't enough gas for a real human being to do two dives on, but they've been quite manageable from a weight standpoint (even if Blitz says I can't schlep my own gear, just because I didn't want to pick it up off the ground ) Peter's HP 100s are very little different in weight, and if I decide I'm diving doubles enough to make it worth while, I'll definitely borrow a set of those to try before I buy anything.

Lynne is not a real human when it comes to gas consumption. On a recent dive together, I was fighting some double 95s to the point where I used 1500 psi on a 51 minute dive that spent a fair amount of the time around 60 feet. My RMV popped up to 0.9 or a bit higher-it was one of those dives where I never really got in the groove trim wise (and this was one of my highest RMVs since I started diving dry-it has been getting down to 0.7 or a bit less in singles).

Afterwards, I checked her SPG, she used 600 psi of gas in those double 72s. That is like me taking a breath a minute.