ucfdiver
Contributor
This one is a bit long, I really debated posting it, but I think in this area of the forum it can be of some use, I would request that it not be copied anywhere because of the math it discusses. I suppose that if I don't post a dive report, I can't complain about only hearing reports on the grand traverse, bats, or godzilla circuit yet again.
(Milky vis in the basin)
For many of us who live in Florida, Manatee Springs is an interesting, cave. It’s no where near the prettiest, it’s not the longest, deepest, shallowest, or anything else for the record books, but it’s easy to get to. It’s challenging due to visibility, depth changes, length, high flow, and a variety of reasons. It’s kicked my butt a few times now, but it seems that every dive you plan here, you’ll need to plan 2-3, so you can fail the first time, improve the second, and nail it the 3rd.
(No swimming...didn't have to ask me twice!)
A little history, I swam here once and promised myself I'd never come back without a scooter...this is 100% scooter cave, as you can see by the sign, which prohibits swimming there! My first scooter dive in this cave was with Brian (litehedded). We did a 2 stage, 45minute penetration that took us to about 5000ft upstream from Catfish Sink, where my primary light decided to die on me very close to maximum penetration. Communication between the team isn’t easy at this cave to start with, and when you lose a primary, it doesn’t help. Brian and I swapped places, and I lead the way out. Due to the depth changes however, Brian’s 21w was more trouble than help, as my Halcyon Scout wasn’t enough to see anything once my eyes were adjusted to the backscatter caused by Brian’s HID, which was blocked every time there was a duck under, leaving me blinded over and over. We ended up having to kill Brian’s primary light and exit both using scouts. With the scooters and flow to our advantage, we were moving about 200ft/min through the cave, on a Xenon Scout, trying to keep focus on a “gold” line that is almost stained black just like the cave walls. Once we saw the cavern zone, we were relieved, and the only good part about a failed dive is that the deco is minimal.
A few more dives later, we were doing well with 2 stages and 1 scooter, so Marchand and I decided that it was time to challenge ourselves a bit more. We decided that we would each use 2 scooters, but up the conservatism on the burn time. For this dive, we would only be burning the scooters 40 minutes on the way in, leaving almost double the burn time on exit. Pfcaj was nice enough to loan me a second scooter for the dive, which was nice because I didn’t have to rent one…and it gave me someone else’s scooter for the further reaches of the cave, so if we had to lose one 10,000ft back, it wouldn’t be mine!
Adding the extra scooter places additional logistical challenges to put it lightly. Aside from Cave 3 via NAUI/GUE/UTD which I’ve yet to meet anyone who’s taken, there really aren’t any courses that you can rely on to teach these types of dives. You’re forced to think for yourself, and talk with divers you respect.
I debated posting any more detail than this, but I think that dives like this really force you to think, and that’s a good thing. There was a death not too long ago from divers at Jackson Blue who misunderstood a gas plan for scootering, so I want to reinforce that this is simply our thought process for a certain dive. For a dive like this, I completely ignore 1/3rds during the planning period. Once the plan is done, if 1/3rds is more conservative than our plan, we use that, but that gets saved for last.
From previous dives and talking with people who've been there, we knew that just beyond about where we think the mile mark is (where we had been a few times, at least I think...where gold line ends), there was a large clay hill that had potential to get very silty, especially so on scooters. This weighed heavily into our decisions. The first step to any plan is to realize what you’re planning for, and we saw the following as the worst-case yet realistic scenario:
• Failed scooter at max penetration.
• Complete loss of a gas source at max penetration.
• Silt-out at max penetration.
Well, the failed scooter isn’t a big deal, you just tow your buddy out. We’ve prepared for this by limiting burn time to 40 minutes, as we have plenty of battery power to tow a buddy out, especially with the flow at our backs on exit.
Complete loss of a gas source, more specifically back gas, is a bit harder to deal with. 10,000ft back in a cave is no place to be sharing the long hose all the way home. Scootering this far back has only one option, and that’s breathing stages in my opinion. There’s just too much risk in towing for a distance this far, and scootering side by side is difficult in a dark cave like this, plus the risk of mismatching speeds and pulling the long hose makes the whole situation something we want to avoid. We decide that however much gas we use to travel, ½+200 and not touching backgas is the way to go here, because losing up to 6 stages, or all of backgas still leaves the diver with enough independent gas sources to exit the cave.
To address the final failure, a silt out in the back of the cave is extremely tricky. I hate to be grim, but if you have a silt out and have to swim as far as 2 scooters took you in…well you’re dead. Sometimes you can plan yourself out of a dive, and this is where you have to keep a close eye on that. We decided that not being able to scooter is completely reasonable, but for how far? Well, we determined that 5000ft without scootering is an overly conservative number, but at this depth easy enough to plan for that we were OK with that. Since the flow moves about 50fpm, the gavin runs about 150fpm, and we swim 50fpm, we would need 5000/(flow+swim) + 5000/(flow+scooter) for exit, or 5000/100 + 5000/200 for a total of 75 minutes to exit the cave. With an average depth of 70ft, our bailout gas with an elevated sac of .65 average would be 75* (70/33+1) * .65, or 152cu ft of gas.
A bit more fun part of all this is the positive planning. We just need enough gas to enter the cave for 80 minutes, but with a sac rate of .5 this time, since it’s a non emergency and won’t be elevated, but we still want some fudge room so we don’t cut our dive short. 80*(70/33+1) * .5 = 124cu ft of gas. Since each stage bottle contains 33 cu ft of gas we can use going in (assuming ½+200), we need 124/33, or 4 stages. Since 4 stages is more than we can carry easily, we decided to use 21/50 in 2 of them. This would allow them to float nicely. It’s not a standard gas, but for this dive, it really doesn’t matter since we’re at 70ft.
And finally, the easy part. We need enough deco gas for the worst case scenario exiting, so 80min in + 75min out = 155min dive time at 70ft. I don’t have deco planner on this computer, so I forget the exact numbers, but they were close enough that we decided to drop an additional 40 of o2 “just on case” since we had it easily accessible anyways.
(Unloading the gear)
Here’s the most disappointing part of the story…the big day came. We decided to put in at Friendmans sink as that got us a bit further upstream. This requires about ¼ mile walk down a trail from the nearest parking spot, carrying all 8 stages, 4 scooters and 3 deco bottles, with Florida Mosquitoes having a feast, and I’m sweating to death in near 100 degree heat. Friedmans is almost always nasty on the surface, so we didn’t think much of it. We made about 4 trips with the hand truck and were finally ready to dive. We hopped in the car to turn on the AC, hydrate even more, and cool off before getting in the dry suits.
(Friedmans Surface)
After getting in the water, we spent about 15 minutes dropping tanks and scooters down a vertical hole in the bottom of the sink which was only big enough for 1 diver to push bottles ahead, and was zero visibility after only one trip down.
Once all of that was done, it was time for some fun, dive time! Jeff (Marchand) took the lead after we clipped everything off, and I would follow. We were greeted with only 15 feet of visibility, not nearly enough to do the dive at our current skill level. However, about 2000ft ahead, we would cross the milk/sewer tunnel jumps, where traditionally most bad visibility is found, so it was worth at least going that far to check conditions. We went on about 30 minutes and decided that this cave isn’t going anywhere, and we’ll wait for the floods to lower flow and reduce the bad intrusion (dark water). I'm not against diving poor viz, but it adds task loading, stress, increases overall difficulty, and since we live nearby, there's really no reason to attack it in bad conditions.
(Packing it all up)
I couldn’t wait to get packed up, the little bit of deco we had was miserable, knowing that we had all that crap to put away, for nothing. However, hurricane season is coming, better conditions will come, so we just need to practice and get ready for opportunity! For the rest of the summer, we've stuck with river caves and lesser known sinks, haven't even touched my scooters but this once all summer, as conditions here in Florida have been GREAT for that type of diving!
These didn't fit in the story, but here you go-
A deer decided to keep us company while we packed up:
Here's a link to a video that shows the walk from where you park to Friedmans Sink
http://www.facebook.com/v/610320822035
(Milky vis in the basin)
For many of us who live in Florida, Manatee Springs is an interesting, cave. It’s no where near the prettiest, it’s not the longest, deepest, shallowest, or anything else for the record books, but it’s easy to get to. It’s challenging due to visibility, depth changes, length, high flow, and a variety of reasons. It’s kicked my butt a few times now, but it seems that every dive you plan here, you’ll need to plan 2-3, so you can fail the first time, improve the second, and nail it the 3rd.
(No swimming...didn't have to ask me twice!)
A little history, I swam here once and promised myself I'd never come back without a scooter...this is 100% scooter cave, as you can see by the sign, which prohibits swimming there! My first scooter dive in this cave was with Brian (litehedded). We did a 2 stage, 45minute penetration that took us to about 5000ft upstream from Catfish Sink, where my primary light decided to die on me very close to maximum penetration. Communication between the team isn’t easy at this cave to start with, and when you lose a primary, it doesn’t help. Brian and I swapped places, and I lead the way out. Due to the depth changes however, Brian’s 21w was more trouble than help, as my Halcyon Scout wasn’t enough to see anything once my eyes were adjusted to the backscatter caused by Brian’s HID, which was blocked every time there was a duck under, leaving me blinded over and over. We ended up having to kill Brian’s primary light and exit both using scouts. With the scooters and flow to our advantage, we were moving about 200ft/min through the cave, on a Xenon Scout, trying to keep focus on a “gold” line that is almost stained black just like the cave walls. Once we saw the cavern zone, we were relieved, and the only good part about a failed dive is that the deco is minimal.
A few more dives later, we were doing well with 2 stages and 1 scooter, so Marchand and I decided that it was time to challenge ourselves a bit more. We decided that we would each use 2 scooters, but up the conservatism on the burn time. For this dive, we would only be burning the scooters 40 minutes on the way in, leaving almost double the burn time on exit. Pfcaj was nice enough to loan me a second scooter for the dive, which was nice because I didn’t have to rent one…and it gave me someone else’s scooter for the further reaches of the cave, so if we had to lose one 10,000ft back, it wouldn’t be mine!
Adding the extra scooter places additional logistical challenges to put it lightly. Aside from Cave 3 via NAUI/GUE/UTD which I’ve yet to meet anyone who’s taken, there really aren’t any courses that you can rely on to teach these types of dives. You’re forced to think for yourself, and talk with divers you respect.
I debated posting any more detail than this, but I think that dives like this really force you to think, and that’s a good thing. There was a death not too long ago from divers at Jackson Blue who misunderstood a gas plan for scootering, so I want to reinforce that this is simply our thought process for a certain dive. For a dive like this, I completely ignore 1/3rds during the planning period. Once the plan is done, if 1/3rds is more conservative than our plan, we use that, but that gets saved for last.
From previous dives and talking with people who've been there, we knew that just beyond about where we think the mile mark is (where we had been a few times, at least I think...where gold line ends), there was a large clay hill that had potential to get very silty, especially so on scooters. This weighed heavily into our decisions. The first step to any plan is to realize what you’re planning for, and we saw the following as the worst-case yet realistic scenario:
• Failed scooter at max penetration.
• Complete loss of a gas source at max penetration.
• Silt-out at max penetration.
Well, the failed scooter isn’t a big deal, you just tow your buddy out. We’ve prepared for this by limiting burn time to 40 minutes, as we have plenty of battery power to tow a buddy out, especially with the flow at our backs on exit.
Complete loss of a gas source, more specifically back gas, is a bit harder to deal with. 10,000ft back in a cave is no place to be sharing the long hose all the way home. Scootering this far back has only one option, and that’s breathing stages in my opinion. There’s just too much risk in towing for a distance this far, and scootering side by side is difficult in a dark cave like this, plus the risk of mismatching speeds and pulling the long hose makes the whole situation something we want to avoid. We decide that however much gas we use to travel, ½+200 and not touching backgas is the way to go here, because losing up to 6 stages, or all of backgas still leaves the diver with enough independent gas sources to exit the cave.
To address the final failure, a silt out in the back of the cave is extremely tricky. I hate to be grim, but if you have a silt out and have to swim as far as 2 scooters took you in…well you’re dead. Sometimes you can plan yourself out of a dive, and this is where you have to keep a close eye on that. We decided that not being able to scooter is completely reasonable, but for how far? Well, we determined that 5000ft without scootering is an overly conservative number, but at this depth easy enough to plan for that we were OK with that. Since the flow moves about 50fpm, the gavin runs about 150fpm, and we swim 50fpm, we would need 5000/(flow+swim) + 5000/(flow+scooter) for exit, or 5000/100 + 5000/200 for a total of 75 minutes to exit the cave. With an average depth of 70ft, our bailout gas with an elevated sac of .65 average would be 75* (70/33+1) * .65, or 152cu ft of gas.
A bit more fun part of all this is the positive planning. We just need enough gas to enter the cave for 80 minutes, but with a sac rate of .5 this time, since it’s a non emergency and won’t be elevated, but we still want some fudge room so we don’t cut our dive short. 80*(70/33+1) * .5 = 124cu ft of gas. Since each stage bottle contains 33 cu ft of gas we can use going in (assuming ½+200), we need 124/33, or 4 stages. Since 4 stages is more than we can carry easily, we decided to use 21/50 in 2 of them. This would allow them to float nicely. It’s not a standard gas, but for this dive, it really doesn’t matter since we’re at 70ft.
And finally, the easy part. We need enough deco gas for the worst case scenario exiting, so 80min in + 75min out = 155min dive time at 70ft. I don’t have deco planner on this computer, so I forget the exact numbers, but they were close enough that we decided to drop an additional 40 of o2 “just on case” since we had it easily accessible anyways.
(Unloading the gear)
Here’s the most disappointing part of the story…the big day came. We decided to put in at Friendmans sink as that got us a bit further upstream. This requires about ¼ mile walk down a trail from the nearest parking spot, carrying all 8 stages, 4 scooters and 3 deco bottles, with Florida Mosquitoes having a feast, and I’m sweating to death in near 100 degree heat. Friedmans is almost always nasty on the surface, so we didn’t think much of it. We made about 4 trips with the hand truck and were finally ready to dive. We hopped in the car to turn on the AC, hydrate even more, and cool off before getting in the dry suits.
(Friedmans Surface)
After getting in the water, we spent about 15 minutes dropping tanks and scooters down a vertical hole in the bottom of the sink which was only big enough for 1 diver to push bottles ahead, and was zero visibility after only one trip down.
Once all of that was done, it was time for some fun, dive time! Jeff (Marchand) took the lead after we clipped everything off, and I would follow. We were greeted with only 15 feet of visibility, not nearly enough to do the dive at our current skill level. However, about 2000ft ahead, we would cross the milk/sewer tunnel jumps, where traditionally most bad visibility is found, so it was worth at least going that far to check conditions. We went on about 30 minutes and decided that this cave isn’t going anywhere, and we’ll wait for the floods to lower flow and reduce the bad intrusion (dark water). I'm not against diving poor viz, but it adds task loading, stress, increases overall difficulty, and since we live nearby, there's really no reason to attack it in bad conditions.
(Packing it all up)
I couldn’t wait to get packed up, the little bit of deco we had was miserable, knowing that we had all that crap to put away, for nothing. However, hurricane season is coming, better conditions will come, so we just need to practice and get ready for opportunity! For the rest of the summer, we've stuck with river caves and lesser known sinks, haven't even touched my scooters but this once all summer, as conditions here in Florida have been GREAT for that type of diving!
These didn't fit in the story, but here you go-
A deer decided to keep us company while we packed up:
Here's a link to a video that shows the walk from where you park to Friedmans Sink
http://www.facebook.com/v/610320822035
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