My questionable rebreather training experience
- Thread starter reefrat
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what pete said. your weighting requirements are your weighting requirements, min loop volume or not. 20lbs sounds very heavy to me on OC, but without knowing your body composition I can't really comment. I know that I need 12lbs total *6-8lbs on the belt* with an AL80 and SS backplate in a 7mm in the ocean, and no lead if using a PST steel tank. I'm pretty negatively buoyant naturally though, so 20lbs total if you are a floater is probably about right in a new 5mm. On a CCR it shouldn't change that much assuming the breather has the same buoyancy as the tank you are diving. Average tidal volume should only be between .5-1L which should only add 1-2lbs to your total lead requirements. I have no idea if the explorer floats, though I expect it would since it is mostly plastic. Either way, you could/should have done a full weight check when you were off the loop to not skew the results by loop volume which it sounds like you didn't do, and that's a shame on your instructor for not doing it, but also somewhat shame on you for not insisting you do it if you knew it wasn't enough lead.
glad to see you remedied your issues though and glad you posted this thread
@vincent54 his previous crimes and time served are irrelevant to the initial part of this post, and regardless of what he did in the past, that doesn't change what is going on now, and more importantly doesn't change the experience that @reefrat had
OP
reefrat
Contributor
Either way, you could/should have done a full weight check when you were off the loop to not skew the results by loop volume which it sounds like you didn't do, and that's a shame on your instructor for not doing it, but also somewhat shame on you for not insisting you do it if you knew it wasn't enough lead.
Thank you for your comments and I totally agree with all, normally I would have been more assertive but I was going with the whole "you are a novice again" thing on a rebreather and tried to trust the instructor.
You raise an interesting point in relation to the loop tidal volume of 0.5 to 1 ltr- if this is the case then a full loop flood would not be the buoyancy issue that I have repeatedly heard provided the diver was not seriously over-weighted?
I suspect that the explorer has a larger than usual loop volume due to the design of loop. The counter lungs exit the scrubber canister at the lower side and a certain amount of gas would have to be pooling in the region of the counter lungs between this point and the upper margin of the CL's which is above the scrubber canister. If the upper CL's were not full then the LCV would not be able to vent because no gas would reach it and the diver would have to physically suck the gas down from whatever was available in the upper CL. I think this may have been my situation during my course because now that I let the LCV do it's job there is always plenty gas available for a relaxed respiratory cycle?
Thank you for your comments and I totally agree with all, normally I would have been more assertive but I was going with the whole "you are a novice again" thing on a rebreather and tried to trust the instructor.
You raise an interesting point in relation to the loop tidal volume of 0.5 to 1 ltr- if this is the case then a full loop flood would not be the buoyancy issue that I have repeatedly heard provided the diver was not seriously over-weighted?
I suspect that the explorer has a larger than usual loop volume due to the design of loop. The counter lungs exit the scrubber canister at the lower side and a certain amount of gas would have to be pooling in the region of the counter lungs between this point and the upper margin of the CL's which is above the scrubber canister. If the upper CL's were not full then the LCV would not be able to vent because no gas would reach it and the diver would have to physically suck the gas down from whatever was available in the upper CL. I think this may have been my situation during my course because now that I let the LCV do it's job there is always plenty gas available for a relaxed respiratory cycle?
I get amazed how often we see people blame the student for not "knowing" they should have done something. That's why they pay us, to learn what they need to learn. The assumptions that earlier training OC will teach stuff like weighting that they should somehow "know" will work cc is only half the story.
Students "don't know what they don't know" and unfortunately often end up being certified "not knowing what they weren't taught"
Students "don't know what they don't know" and unfortunately often end up being certified "not knowing what they weren't taught"
_Slacker_
Contributor
I guess this is why they made a big deal about how much lead was trimmed off the students in a recent photo on their FB page. I didn't really get it at the time, but if you think it's better to dive underweighted emphasizing that point would be important. It seems to make more sense now.
Interesting statement. I only hear it's the DM's fault or Instructors fault. Especially in a lawsuit.
I agree, if the instructor isn't giving adequate training the fault is all on him/her. I also think it's up to the dive industry to monitor its instructors and get rid of the incompetent ones. Or let the government come in and oversee, and see how that works.
I agree, if the instructor isn't giving adequate training the fault is all on him/her. I also think it's up to the dive industry to monitor its instructors and get rid of the incompetent ones. Or let the government come in and oversee, and see how that works.
Like most industries, there's simply no mechanism for that. The best bet is to post the good, the bad and the ugly all over the interwebs. That's why we exist.
Take my favorite subject: trim and neutral buoyancy. It really needs to be a part of the OW class. It's how divers get comfortable in the water, but it's not normally anything but an afterthought. ScubaBoard has done more to promote this than any agency or other entity. We've even caused a few agencies to take notice of it. The interwebs have power. This is a hotter topic now than it has ever been.
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