Tech / Deep Diving at Mansfield Dam - 22-23

[FIXXERVI6]

I've had a second hand report of the vis at 145 being almost touch communication, I tend to believe it from the reports I have been hearing and the temerpature profile of the lake.

 

[cyklon_300]

Any truth to the viz being bad at Mansfield below 100’ lately? When I did my deco class there last summer, the viz was really great below 60 feet or so - could really see the beer cans…

D.

nah, we just make this stuff up as we go along...since the lake has no seasonal or dynamic variation, the vis should probably be the same as last summer.

Don't forget to bring some EAN80...

 

[Crazyduck]

Gregg,
Talk about laugh…
That’s one way to get my coffee all over my keyboard.
Dude too funny! :evilsmile

Andrew

nah, we just make this stuff up as we go along...since the lake has no seasonal or dynamic variation, the vis should probably be the same as last summer.

Don't forget to bring some EAN80...

 

[loosebits]

loosebits - yeah - I was planning on slinging a pretty rich mix to cut the deco time down…are you going to be down there for fun? Class?

For fun. What I am saying is with profiles in the 150' range on air, EAN50 will get you out of the water faster.

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 140ft (2) Air 50ft/min descent.
Level 140ft 27:12 (30) Air 1.10 ppO2, 140ft ead
Asc to 70ft (32) Air -30ft/min ascent.
Stop at 70ft 2:40 (35) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 1:00 (36) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 1:00 (37) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 4:00 (41) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 4:00 (45) Nitrox 50 0.95 ppO2, 7ft ead
Stop at 20ft 7:00 (52) Nitrox 50 0.80 ppO2, 1ft ead
Stop at 10ft 13:00 (65) Nitrox 50 0.65 ppO2, 0ft ead
Surface (65) Nitrox 50 -30ft/min ascent.

vs

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 140ft (2) Air 50ft/min descent.
Level 140ft 27:12 (30) Air 1.10 ppO2, 140ft ead
Asc to 70ft (32) Air -30ft/min ascent.
Stop at 70ft 0:40 (33) Air 0.65 ppO2, 70ft ead
Stop at 60ft 3:00 (36) Air 0.59 ppO2, 60ft ead
Stop at 50ft 4:00 (40) Air 0.53 ppO2, 50ft ead
Stop at 40ft 5:00 (45) Air 0.46 ppO2, 40ft ead
Stop at 30ft 9:00 (54) Air 0.40 ppO2, 30ft ead
Stop at 20ft 6:00 (60) Oxygen 1.60 ppO2, 0ft ead
Stop at 10ft 9:00 (69) Oxygen 1.30 ppO2, 0ft ead
Surface (69) Oxygen -30ft/min ascent.

 

[ianr33]

In all honesty the viz is really sucky below about 100 feet. I think the deepest dive I have done this year is 105. Even with HID's not losing your buddy is a challenge. (Have not been to Mansfield this year,but I assume it is pretty much the same as Windy Point)

 

[LVX]

I have been to mansfield this year. Actually I have been there 3 times over the past 5 weeks. The deepest I have been there is 130. Viz sucks.....

 

[FIXXERVI6]

Hey guys -

Heading down with a buddy to do some training in Lake Travis this weekend to do some tech/deep dives - prolly in the 120-140 range. We'll be using doubles and 100% o2 for deco stage bottles. Need to get those dives in so I can take Ext. Range and Trimix this summer!

Anyone in?

D.

Just out of curiousity what are your goals, cave, wreck, cards, bottom of lakes?

 

[loosebits]

nah, we just make this stuff up as we go along...since the lake has no seasonal or dynamic variation, the vis should probably be the same as last summer.

Don't forget to bring some EAN80...

Are you making a dig on my EAN50 comment? From what I've seen, EAN50 generally gets you out of the water faster than O2 when you have a low ppO2 at max depth (e.g. air at 140). Doing EAN26 at 140' for 30 mins, O2 is the better choice for deco. The reasoning is that with a low ppO2 at depth, the earlier you can get on a higher ppO2 (70' vs 20'), the better.

Of course both would be great but who wants to haul two bottles for such a shallow dive?

 

[Crazyduck]

Rand,
You make a good point.
While straight O2 is incredible there are serious side issues.
Straight Oxygen is a fickle beast and does not give any leeway.
Plus, it has depth restrictions.
Where 50% is earlier to jump onto and you can ride it longer.

I think at this point we should start watching our shifts in nitrogen also. This is more of a trimix issue but still good to start watching- I don’t want to get a Nitrogen shift or ‘slam’ in my ears.

Presently, I am passing on diving below 100 ft until the vis clears up.
Not enough reward for the problems.

Andrew

 

[JeffG]

Are you making a dig on my EAN50 comment? From what I've seen, EAN50 generally gets you out of the water faster than O2 when you have a low ppO2 at max depth (e.g. air at 140). Doing EAN26 at 140' for 30 mins, O2 is the better choice for deco. The reasoning is that with a low ppO2 at depth, the earlier you can get on a higher ppO2 (70' vs 20'), the better.

Of course both would be great but who wants to haul two bottles for such a shallow dive?

The 80% comment means something else.

Ext Range is not required for the Trimix cert. Ext Range does two things. either a) Instructor gets more of your cash or b) another chance to help you with your skills. Depending on instructor.

50% is better choice if you are only going to take 1 deco gas.