Any U-853 experience you want to tell.

[mixdiver]

As usual, Matt and I disagree on dive planning.

I would have to agree with soggy on the dive planning. You never no what is going to happen. In a true emergency most peoples air consumption could double or even more. I cant wait to dive her myself. Safe diving.

 

[Soggy]

FWIW, here is my trip report from the U853 back in June:
http://thedecostop.com/forums/showthread.php?t=14219

And here is what *can* happen when you depend on your pony being there by not doing proper rock-bottom gas planning (no, I don't want to debate pony bottles, but it is food for thought about how to use and rig one):
http://www.scubaboard.com/showthread.php?t=74063

 

[matt_unique]

As usual, Matt and I disagree on dive planning.

Ha ha ha - hey - we can still be NELD friends.

If one were to do this entire dive with a 1 CF/M/ATA SAC rate they would still surface with about 24CF of gas which is nearly 1/3 of the AL80 assuming a 3000psi fill. The 30 or 40CF pony bottle for an OOG emergency is plenty for an ascent and a safety stop. Even following your example, the 10 min bottom time is all that would allowed in an NDL anyway.

To be fair, the article you (Soggy) referenced involved lots of things going wrong including "accidental" deco obligations, a leaking pony bottle, getting lost, etc. The rock bottom calculations you discussed would not have addressed the problems referenced in the article since a dive plan was not followed.

Nothing wrong with over planning but you can absolutely do an NDL dive on the U853 with an AL80 and a 30 or 40CF pony bottle. Before I switched to doubles for all boat diving I did NDL's on the U853 with AL 80's and surfaced with 2000psi and of course a full 30CF pony bottle.

--Matt

 

[large_diver]

Don't want to open the pony/no-pony debate...

But....if you are planning to use a pony on a dive like this, better to practice with it on shallower dives first....

 

[JimJam]

Soggy-

You make some excellent points...I asked the question just to see what other people thought and did, not because I am ignorant of gas management (I am not a master of it either) I actually had a trip to the 853 scheduled earlier this year, but it was cancelled because of an underbooked boat...after learning more about gas management, I took the cancellation as a "sign" and haven't even thought of re-booking until I can get some bigger tanks. I'm sure there have been many dives completed on the 853 with AL-80s, maybe even less. But I know there have been dives to comparable and deeper depths that have turned out horribly.

Bottom line is I think you are right. Gas management on a dive like this is crucial, and is probably disregarded by too many divers.

 

[Soggy]

Ha ha ha - hey - we can still be NELD friends.

Group hug for everyone!

You're right, there was way more wrong in that story than just the pony bottle...like I said, it was just food for thought about what can happen when you don't plan a dive properly and when you assume that gas is there when it isn't. Clearly a pony bottle can be dived intelligently and safely, though as is well known, I am not a proponent of them.

The only point I wanted to really make was PADI 101....plan your dive and dive your plan. The margins for error at these depths on a small single tank are very small.

 

[matt_unique]

....
The only point I wanted to really make was PADI 101....plan your dive and dive your plan. The margins for error at these depths on a small single tank are very small.

Agreed - smaller margin for error with a smaller gas supply and deeper depths. Gas management and planning is way crucial for any dive including this one. I would say the U853 is one of the most advanced 125' wreck dives you could do. It's also one of the most inspiring.

Hopefully we'll have good weather for all the planned dives. My last time out we were busted. I had actually grabbed the mooring but after an assesement of the seas decided to head back to the island. Block Island was sheltering the wind and seas for a portion of the journey to the wreck and by the time I arrived the seas were 4-6 with white capping tops and strong winds. I have also been out there with almost flat calm seas and I could run full cruise speed all the way out and back. Those days are nice....

--Matt

 

[Green_Manelishi]

When you get to the bottom, make sure you are positive which line you came down....there are a bazillion ghost lines from old moorings and you don't want to come up the wrong one....

Attach an unique strobe/flasher light to the line BEFORE you let go of the line.

 

[matt_unique]

This will get you started as a basic site map. I found/printed this picture years ago and made my own (hand written) additions as the conditions changed. I would suggest you do the same as you dive it. The attached picture does not reflect the stern break or the bow tip I referenced earlier. The depth for the top of the structure is off too - 118' is more accurate give or take a few feet based on the tide.

--Matt

 

[ScubaSarus]

Hey nice picture.

Also for a second dive I'm sure an 80 can be done since the planned bottom time will be less than the first dive. But as always more air = better air. Pony mandatory.

Chris