mi000ke
Contributor
- Messages
- 1,142
- Reaction score
- 1,734
- Location
- Massachusetts & Grand Cayman Island
- # of dives
- 200 - 499
(Apologies for the long post.)
I am pretty familiar with the issues involved in proper weighting – I actually constructed a spreadsheet for myself that computes my net buoyancy at beginning, midpoint, and end of dive at 0, 33, 66 and 99’ (accounting for suit thickness, compression, air consumption, net tank weight, body buoyancy, and equipment).
So I computed my proper weight to both get me below the surface after a good exhale (I’m a sax player and know how to clear my lungs pretty well) as well as get neutral at my safety stop (I can also compute neutral at surface at end of dive as well).
Anyway, my correct weight to get me down as well as to get close to neutral at the end is 16 lb (I weigh 150 lb and have always dived a 5mm full suit and when water temp < 75, a hood and boots as well). Actually I can do 15 # without the hood and boots but it’s easier to work with even numbers. I have done 25 dive with my “proper” weighting, and it seemed to work just fine.
I am doing my AOW this week, and did PPB for my first dive so my weight and trim would be good for the rest of the course. Now, as an aside, I was taught and always seem to observe that most people descend feet down and just try to sink naturally once they purge their BCD and exhale (but after a search here, discovered that a lot of people duck dive down head first with finning).
Well my instructor insisted I could use less weight, so we tried 14 lb and after purging my BCD and a good exhale I just continued to float – and my instructor observed that I was pretty still. So we agreed that 16 lb was correct.
Well on my third dive of the course we were down with another group and their guide swam over and (as he later explained) thought I had too much air in my bcd (we were at about 95’) and that I was not able to hover motionless fighting the weight, so he took out 4 lbs. – a 25% reduction. And that was perfect for the rest of the dive. But of course at the bottom with the compression of my 5mm I would need much less weight.
So the conundrum was/is, do you weight for the bottom (or some depth below the surface), meaning much less weight (and then have to figure out how to get yourself down), or for the top meaning more weight but making your descent easier?
The other instructor (the one who pulled my weights) suggested it would be better to underweight and pull myself down the anchor line if needed rather than weight for the easy descent (even using the eye level at the surface test).
Well he insisted I do the next dive using 12 lb, and it turned out that if I did a duck dive (again which I was not taught to do, but did in desperation) and finned really hard I was just barely able to get down that 5-10 feet where pressure took over and I was fine. The rest of the dive was buoyantly perfect and he was correct about improved hovering. I was of course more buoyant at the end, but had no problem holding my safety stop depth without having to hold onto the line. I just surfaced with an empty BCD.
So (finally) my questions are, should we under-weight and work really hard (or use an anchor line) to get ourselves down? Is it supposed to require some work to get down? And for those divers who are able to do an easy descent, are they actually overweighed? Or is my situation that unique?
I am pretty familiar with the issues involved in proper weighting – I actually constructed a spreadsheet for myself that computes my net buoyancy at beginning, midpoint, and end of dive at 0, 33, 66 and 99’ (accounting for suit thickness, compression, air consumption, net tank weight, body buoyancy, and equipment).
So I computed my proper weight to both get me below the surface after a good exhale (I’m a sax player and know how to clear my lungs pretty well) as well as get neutral at my safety stop (I can also compute neutral at surface at end of dive as well).
Anyway, my correct weight to get me down as well as to get close to neutral at the end is 16 lb (I weigh 150 lb and have always dived a 5mm full suit and when water temp < 75, a hood and boots as well). Actually I can do 15 # without the hood and boots but it’s easier to work with even numbers. I have done 25 dive with my “proper” weighting, and it seemed to work just fine.
I am doing my AOW this week, and did PPB for my first dive so my weight and trim would be good for the rest of the course. Now, as an aside, I was taught and always seem to observe that most people descend feet down and just try to sink naturally once they purge their BCD and exhale (but after a search here, discovered that a lot of people duck dive down head first with finning).
Well my instructor insisted I could use less weight, so we tried 14 lb and after purging my BCD and a good exhale I just continued to float – and my instructor observed that I was pretty still. So we agreed that 16 lb was correct.
Well on my third dive of the course we were down with another group and their guide swam over and (as he later explained) thought I had too much air in my bcd (we were at about 95’) and that I was not able to hover motionless fighting the weight, so he took out 4 lbs. – a 25% reduction. And that was perfect for the rest of the dive. But of course at the bottom with the compression of my 5mm I would need much less weight.
So the conundrum was/is, do you weight for the bottom (or some depth below the surface), meaning much less weight (and then have to figure out how to get yourself down), or for the top meaning more weight but making your descent easier?
The other instructor (the one who pulled my weights) suggested it would be better to underweight and pull myself down the anchor line if needed rather than weight for the easy descent (even using the eye level at the surface test).
Well he insisted I do the next dive using 12 lb, and it turned out that if I did a duck dive (again which I was not taught to do, but did in desperation) and finned really hard I was just barely able to get down that 5-10 feet where pressure took over and I was fine. The rest of the dive was buoyantly perfect and he was correct about improved hovering. I was of course more buoyant at the end, but had no problem holding my safety stop depth without having to hold onto the line. I just surfaced with an empty BCD.
So (finally) my questions are, should we under-weight and work really hard (or use an anchor line) to get ourselves down? Is it supposed to require some work to get down? And for those divers who are able to do an easy descent, are they actually overweighed? Or is my situation that unique?