LP45/50s in cave diving

[crofrog]

You have to do the math. SAC rate, Swim Speed, Difficulty of the dove. Familiarity of the cave.

Remember 20 years ago lots of people were taking a single LP104 with a Y-Valve on Intro to Cave dives just fine. And an LP104 with a Yvalve isn’t true redundancy like twin lp50s

So, pumped up lp50’s might be 72cu’ for each. 144cu’ total. 48cu’ of penetration at .5 sac rate with a 50fpm swim speed in 100’ of water is 600’ of penetration.

Of course what is your buddy diving for the purposes of gas matching?

Imagine you’re at peacock. Say average depth 45’, same sac and you’ve got over 1000’ of penetration. I got no problem with that. But add a CCR and now at Ginnie you can swim the entire map this side of 2000’ and at Peacock with multiple exits, you have enough bailout to swim the entire map.

I can show you the math if need be.

I understand the math I was just curious what his limits were for it.

It seems like 2000’ back at Ginnie is pretty achievable on open circuit

 

[Superlyte27]

I understand the math I was just curious what his limits were for it.

It seems like 2000’ back at Ginnie is pretty achievable on open circuit

I wouldn’t be doing that dive on OC. But 2000’ is my max pen on CCR at Ginnie.

Here’s why…
I can easily average 75fpm anywhere in the ginnie system this side of 2000’. I have probably 1500 dives in the first 4000’ of Ginnie. And know the system very very well. I doubt there will be any surprises that would shock me. I calculate a 1cfm sac and while not all of ginnie is 4 ata, most of it is. My actual sac rate is less than half that. At this level of the game, unless a shark tried to eat me IN GINNIE, I don’t think I’d be over 1cfm. So 4cu’/min, 75fpm swim speed and my max penetration on LP50s is just over 2000’. It’s actually like 2600. But I like round numbers and conservatism.

What’s great is, that I can see ALL of ginnie on a single dive this side of 2000’, provided my dive buddy is also on CCR.

I wouldn’t call that Alpinist.

 

[Superlyte27]

I just saw the “cave is 500m or more without backup scooter”. Lol. 500m is a baby swim dive. Lol. Lol lol lol. My last brand new intro student made it to 1300’ on LP85s diving to 6ths on her very first ever cave dive at Ginnie. And 500m needs a backup scooter? Lol lol lol. I feel dumb for the engagement.

Guys, I genuinely apologize for arguing with a newb. I didn’t know my audience. I should have never interacted. I promise to try to do better next time. Not kidding.

 

[nadwidny]

But, who the phuck cares? Quit being pedantic. I was cave diving when EVERYONE but the wealthy was doing Intro to Cave on a single 104. Lp50s are better than that due to true redundancy.
And D. Let me know when you have 10% of my background and experience and we’ll start caring about your perspective.

The Force of George Irvine is strong in this one Grasshopper. It's about time someone livened up this place.

 

[Cavevixen]

There’s no demeanor that came to life, I just don’t let non-sense go unanswered. We dove single 104s for DECADES just fine, but suddenly 50s aren’t safe.

Quit talking out your arse and I’ll be on your side, until then, I’m going to support knowledge and experience.

I just saw the “cave is 500m or more without backup scooter”. Lol. 500m is a baby swim dive. Lol. Lol lol lol. My last brand new intro student made it to 1300’ on LP85s diving to 6ths on her very first ever cave dive at Ginnie. And 500m needs a backup scooter? Lol lol lol. I feel dumb for the engagement.

Guys, I genuinely apologize for arguing with a newb. I didn’t know my audience. I should have never interacted. I promise to try to do better next time. Not kidding.

Hey, I was that student!!

 

[berndo]

I doubt there will be any surprises that would shock me. I calculate a 1cfm sac and while not all of ginnie is 4 ata, most of it is. My actual sac rate is less than half that. At this level of the game, unless a shark tried to eat me IN GINNIE, I don’t think I’d be over 1cfm. So 4cu’/min, 75fpm swim speed and my max penetration on LP50s is just over 2000’. It’s actually like 2600. But I like round numbers and conservatism.

If you're doing that, that's one thing. Suggesting, as a cave instructor, 0.5 is a reasonable sac rate after a stressful event like a ccr failure or co2 hit, is another. It should be enough but there is not alot of buffer here for most people... it's not like we've never seen people that should have made it out but didn't.

 

[Superlyte27]

If you're doing that, that's one thing. Suggesting, as a cave instructor, 0.5 is a reasonable sac rate after a stressful event ccr failure/co2 hit, is another. It should be enough but there is not alot of buffer here for most people... it's not like we've never seen people that should have made it out but didn't.

I think you need to read the post again. You surely misunderstood.

 

[berndo]

I think you need to read the post again. You surely misunderstood.

You've said this when ask about swimming out:

So, pumped up lp50’s might be 72cu’ for each. 144cu’ total. 48cu’ of penetration at .5 sac rate with a 50fpm swim speed in 100’ of water is 600’ of penetration.

 

[Superlyte27]

You've said this when ask about swimming out:

Okay, not willing to get into another debate with another newb, but you did see that that was penetration IN right? 1/3 in, 2/3 out in a very high flow main line cave with no restrictions?

Are you referencing the OC post or the CCR post. These are two different animals. Doubt you’re going to take a CO2 hit exiting on an OC dive, lol.

 

[Tom_Ivan]

Struth! How about we all take a deep breath?...


To the OP. Yes I've dived those tanks open circuit sidemount. We call them 5L steels over here. They are my main goto cylinder size.
However, we have very long lengths of dry passage to crawl, walk, climb through before we get to the dive sites. And often the caves are are a hour or so hike through the bush.
If I could just drive up to the water I'd be pulling out much bigger tanks. Why take less air when you could take more for not much more effort?