heavy legs
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Frog Dude
Registered
The body is designed to bend forward at the waist. Properly ballasted in the torso will still result in the legs hanging down from the waist when you relax. Your torso will remain horizontal but the legs will drop.. If you purposefully extend your legs the effort arm extension from the CG established with your BC will effectively move the CG toward your feet and cause your entire body to tilt down by the feet. This is why submarines have forward and aft ballast tanks the use to “Trim the Boat”. You need to employ some type of positive buoyancy near your feet to offset the difference between the weight of water displaced by your legs and feet and the actual weight of your legs and feet. To achieve a horizontal torso hover with your legs hanging down will require some creative weight locations and maybe a thicker suit. Try wearing the BC lower on you back to move some buoyancy closer to your hips.
In response to the “Brain” comment, if it can neither sink, float or grasp simple concepts that are proven to enhance ones ability to process multiple sensations and trigger corrective responses in a timely fashion I would have yours evaluated. If found defective, take corrective action.
In response to the “Brain” comment, if it can neither sink, float or grasp simple concepts that are proven to enhance ones ability to process multiple sensations and trigger corrective responses in a timely fashion I would have yours evaluated. If found defective, take corrective action.
The options I see available to you are, in order of preference IMOdump:
1.) Use the frog kick, which involves flexing at the knees. You can vary the amount of flexion to adjust the center of gravity.
2.) Move the tank up in the BC. This moves the center of gravity forward also.
3.) Adjust the BC to move the bladder closer to your hips. This moves the center of bouyancy towards your hips
4.) Thicker boots will increase bouyancy at your feet.
5.) Lighter fins as was mentioned earlier.
6.) Tank weight--the very least amount possible after all else has failed.
Frog Dude
Registered
dump:
We all want to help the guy but we need to READ what the problem is.
Legs sinking AT REST (Not Kicking) is when he has the problem.
Balloons on the feet will work and was funny as **** but not practical.
I have the same problem and have minimized the problem with thicker boots but still sink like a stone, feet first. It a small price to be in good shape.
Frog Dude
I am aware of his specific problem, which is a mismatch between his center of gravity and his center of bouyancy. I have listed the things he can do to bring these two centers into alignment. Starting with the things he can do for free.
michaelb51
Guest
Floating the feetsies isn't necessarily the wrong answer here.
Wrapping those legs around the anchor line or giving up on relaxing horizontal altogether, citing muscle development combines several delusions though, IMO. You seem to have settled upon a good answer to the central problem, frog dude, but wrapped it at one point in what I consider to be generally bad advice. Stay away from anchor lines. Do not give up on mastering trim and vertical control while motionless. Anyone can feign stability by kicking. That's what we do when we're new at this.
Almost everyone has the CG/CL problem that sinks the feet when they float and relax. A few have the opposite problem. jbd is spot on with his answers, IMO.
I'm sorry if you thought I attacked your brain. I was trying to make the point that fat and muscle are not relevant to this problem. Simple adjustments made in the right order, and determination should find the "hover button" for anyone. Once found, we usually immediately forget how hard it was. And there is usually a "miraculous" reduction in air consumption soon after.
Wrapping those legs around the anchor line or giving up on relaxing horizontal altogether, citing muscle development combines several delusions though, IMO. You seem to have settled upon a good answer to the central problem, frog dude, but wrapped it at one point in what I consider to be generally bad advice. Stay away from anchor lines. Do not give up on mastering trim and vertical control while motionless. Anyone can feign stability by kicking. That's what we do when we're new at this.
Almost everyone has the CG/CL problem that sinks the feet when they float and relax. A few have the opposite problem. jbd is spot on with his answers, IMO.
I'm sorry if you thought I attacked your brain. I was trying to make the point that fat and muscle are not relevant to this problem. Simple adjustments made in the right order, and determination should find the "hover button" for anyone. Once found, we usually immediately forget how hard it was. And there is usually a "miraculous" reduction in air consumption soon after.
Frog Dude
Registered
I concur with all jdbs recommendations except #1 (a good style to develop while diving) but not relevant when motionless. If the general consensus will accept a horizontal hover to include the legs bent up at the knees in a stable freefall frog position the CG will move toward the head and reduce the effective feet down moment.
Michaelb51,
Fat and muscle are the crux of the buoyancy issue. The combination of the two determine the specific gravity of your body. All of the equipment you wear must be compensated for based on the datum of your body SG to achieve a working, adjustable, buoyancy designed for the dive you are going to do.
This was critical when I started diving because we didnt have BCs. With double 72s, ¼ inch full wetsuit, horse collar, booties and fins it took 16 pounds to be neutral at 80 feet. Yea, you had to swim down, but at depth the diving was almost effortless.
The same setup for someone else might require 25 pounds.
Weight distribution is another issue and is highlighted by Dumps original question.
The torso is the only area in the body that contains an adjustable air bladder. The sinuses and intestines static volume remains somewhat constant unless you had beans or broccoli pre dive. The extremities are left with a constant mass per cubic volume.
Which brings us back to the original problem.
I am surprised that nobody zoned in on the physique issue that is the root cause of dumps problem. This was brought into focus by his subsequent post.
Quote: i dont use weight or a weight belt. I am 5 ft 7in weight 235 lbs powerlifter. so i sink with no problems. i will try to add a little to the top of the tank.
If dump will accept a horizontal hover with his legs retracted and wearing his BC around his waist, the problem is solved. Although I think that a section of pipe insulation foam from the hardware store threaded onto his fin straps in conjunction with thicker booties may help and I may try this myself I the pool tonight.
Michael,
You are correct about avoiding the anchor line and I never suggested wrapping my leg around it. If the seas are calm and you wanted to hover in a strict, flat, legs out straight position you can hold the line between your legs. To release just open your legs. In 32 years of diving I was never bent DECOing in the vertical position using the center of my chest at the correct depth.
Frog Dude
BTW jdb the drills used when I received training with my first BC we were taught to pivot on our fin tips. Breath control was stressed and to pass the drill you had to stay within a +- 3 inch span for 20 minutes.
FD
Michaelb51,
Fat and muscle are the crux of the buoyancy issue. The combination of the two determine the specific gravity of your body. All of the equipment you wear must be compensated for based on the datum of your body SG to achieve a working, adjustable, buoyancy designed for the dive you are going to do.
This was critical when I started diving because we didnt have BCs. With double 72s, ¼ inch full wetsuit, horse collar, booties and fins it took 16 pounds to be neutral at 80 feet. Yea, you had to swim down, but at depth the diving was almost effortless.
The same setup for someone else might require 25 pounds.
Weight distribution is another issue and is highlighted by Dumps original question.
The torso is the only area in the body that contains an adjustable air bladder. The sinuses and intestines static volume remains somewhat constant unless you had beans or broccoli pre dive. The extremities are left with a constant mass per cubic volume.
Which brings us back to the original problem.
I am surprised that nobody zoned in on the physique issue that is the root cause of dumps problem. This was brought into focus by his subsequent post.
Quote: i dont use weight or a weight belt. I am 5 ft 7in weight 235 lbs powerlifter. so i sink with no problems. i will try to add a little to the top of the tank.
If dump will accept a horizontal hover with his legs retracted and wearing his BC around his waist, the problem is solved. Although I think that a section of pipe insulation foam from the hardware store threaded onto his fin straps in conjunction with thicker booties may help and I may try this myself I the pool tonight.
Michael,
You are correct about avoiding the anchor line and I never suggested wrapping my leg around it. If the seas are calm and you wanted to hover in a strict, flat, legs out straight position you can hold the line between your legs. To release just open your legs. In 32 years of diving I was never bent DECOing in the vertical position using the center of my chest at the correct depth.
Frog Dude
BTW jdb the drills used when I received training with my first BC we were taught to pivot on our fin tips. Breath control was stressed and to pass the drill you had to stay within a +- 3 inch span for 20 minutes.
FD
michaelb51
Guest
Frog Dude:
Yes, I suppose so, in the same way that water and air are the crux of the drowning issue. But regardless of distribution and ratio, one is left with a sum of lifting and sinking moments and the need to move them to a desired location, as you said. That procedure is the same for everyone. I personally find that after several hours holding trim with my leg muscles I become dangerously feeble. I was responding to what I saw as a suggestion that this could be a solution, rather than trimming.
The only thing I see wrong with a more vertical position, BTW, would be in the event it was involuntary.
Frog Dude:
cummings66
Contributor
I had a similar problem with my feet sinking very easily once I stopped moving. I've solved that problem using lots of things. First and I hate to say it but when I switched to a BP/W it made a night and day difference with my trim. With the old jacket style BC I had no weight belt because it was integrated and I kept my weights in the top trim pockets and weight on the top of the tank in a cam band. I still had feet sinking issues and the tank was hitting my head I had it so high up. I tried some Genesis and Mare's jacket style BC's with no difference in that, the weight could not go any higher either.
Once I switched to a BP/W it changed a lot and now takes little weight to get the trim right. I dive a 7mm wetsuit and a Viking Drysuit. I use no more weight than the 13 lbs with the plate and the trim is very close to perfect. I use the frog kick and keep my legs bent at the knee at rest as well. I trim for how I primarily dive, and that's horizontal with a frog kick.
So in essence the fix was to go to a BP/W, carry no more weight than the 13 lbs from the plate and a steel tank. I do not use a weight belt because even 6 lbs on my hips will make my feet sink, though slowly. The drysuit is what I dive for the most part around here, but the weight situation is similar with the 7mm Akona wetsuit. I never did need ankle weights with the drysuit to the surprise of my instructor.
I'm not in what I would call great shape either, a bit of flab on the belly here and there although my legs are pretty much flab free. I'd say JBD is right on target and would only add that maybe he should try a plate and wing instead of a jacket style BC, it's fixed many peoples trim issues.
Once I switched to a BP/W it changed a lot and now takes little weight to get the trim right. I dive a 7mm wetsuit and a Viking Drysuit. I use no more weight than the 13 lbs with the plate and the trim is very close to perfect. I use the frog kick and keep my legs bent at the knee at rest as well. I trim for how I primarily dive, and that's horizontal with a frog kick.
So in essence the fix was to go to a BP/W, carry no more weight than the 13 lbs from the plate and a steel tank. I do not use a weight belt because even 6 lbs on my hips will make my feet sink, though slowly. The drysuit is what I dive for the most part around here, but the weight situation is similar with the 7mm Akona wetsuit. I never did need ankle weights with the drysuit to the surprise of my instructor.
I'm not in what I would call great shape either, a bit of flab on the belly here and there although my legs are pretty much flab free. I'd say JBD is right on target and would only add that maybe he should try a plate and wing instead of a jacket style BC, it's fixed many peoples trim issues.
Frog Dude
Registered
A pound of feathers and a pound of lead weigh the same on the surface.
Half a pound of feathers on an extended moment (further away from the fulcrum) will balance out the pound of lead.
Submerge them and everything changes.
Density to mass. If a pound of feathers filled 1 cubic foot the equivalent cubic foot of water (fresh) will weigh 62.38 pounds.
If a cross section of ones anatomy was taken and the specific gravity measured if the result is greater than 1, it will sink. This is basic physics.
Chasing the perfect trim will be dependant on body position. Find the position that you assume totally relaxed. Be it legs straight out or knees slightly bent.
Adjust your weights as practical.
I do have a problem telling someone to mount their tanks higher on the backpack. I have seen a few head lacerations from whacking into the J valve.
Thicker booties, adding knee or thigh patches or even a thicker bottom section of your wetsuit will make your lower portion more buoyant. I will try the pipe insulation on the fin strap tonight and give a report later.
But you cannot discount the fact that the body’s fat to muscle ratio will effect not only buoyancy but trim also.
Frog Dude
Half a pound of feathers on an extended moment (further away from the fulcrum) will balance out the pound of lead.
Submerge them and everything changes.
Density to mass. If a pound of feathers filled 1 cubic foot the equivalent cubic foot of water (fresh) will weigh 62.38 pounds.
If a cross section of ones anatomy was taken and the specific gravity measured if the result is greater than 1, it will sink. This is basic physics.
Chasing the perfect trim will be dependant on body position. Find the position that you assume totally relaxed. Be it legs straight out or knees slightly bent.
Adjust your weights as practical.
I do have a problem telling someone to mount their tanks higher on the backpack. I have seen a few head lacerations from whacking into the J valve.
Thicker booties, adding knee or thigh patches or even a thicker bottom section of your wetsuit will make your lower portion more buoyant. I will try the pipe insulation on the fin strap tonight and give a report later.
But you cannot discount the fact that the body’s fat to muscle ratio will effect not only buoyancy but trim also.
Frog Dude
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