Weighting/Trim Question

[RJP]

We were doing drills -

What kind of drill involves ditching weights at depth?

 

[Basking Ridge Diver]

From when I first learned - we would don and doff our "horse collars" on a monthly basis and take your mask off with buddy breathing. I cant help it - those drills are still with me. So now with an integrated BC - once you doff - your weights are coming off with the doff... Unless I am missing your point - which I could be.
So with out first finding out how that was going to work for the first time - I figured take one pocket out at a time and see how that works and it it worked...
In the old days my weight belt was what kept me down - we did not have the option to split up the weights - or at least I never thought about it...

 

[boulderjohn]

I am going to agree with those who cannot believe you need that much weight. I am not far from you in size, and with a 3mm suit and a jacket BCD in salt water, I use 8 pounds.

I recently did an OW dive with a couple of students in cool, fresh water. The needed 7mm suits. One of them had used a 7mm suit in the pool, and he said his work there (I was not present) convinced him he needed 22 pounds. By the time we were done, he was diving happily with a grand total of 10 pounds. (He was small and thin.) I would love the chance to work with you on this, but that is obviously not going to happen.

As far as distributing your weight, the solution with a jacket BCD is to get much more up high than you did. Many BCDs have trim pockets up by the shoulders. Failing that, you can add weight pockets to the cam bands of the BCD. You had 2 pounds there--not nearly enough.

 

[Yellowdog]

I was diving in a fresh water Quarry a few weeks ago getting my AOW. Peak buoyancy was one of the dives. At 6'1", 223lbs, with a new full 7mm suit, hood, boots, gloves, and an AL80, I was using 26lbs of lead. 9 in each bcd pocket and 4 in each trim pocket. I am guessing from most of the comments here that I was "way over weighted" but I was able to stay neutral and do all the skills fairly easily, in fact I felt very comfortable. Next I will try leaving a couple of pounds on the dock and see how it goes.

 

[boulderjohn]

I was diving in a fresh water Quarry a few weeks ago getting my AOW. Peak buoyancy was one of the dives. At 6'1", 223lbs, with a new full 7mm suit, hood, boots, gloves, and an AL80, I was using 26lbs of lead. 9 in each bcd pocket and 4 in each trim pocket. I am guessing from most of the comments here that I was "way over weighted" but I was able to stay neutral and do all the skills fairly easily, in fact I felt very comfortable. Next I will try leaving a couple of pounds on the dock and see how it goes.

There is a big difference between a new 7mm w/hood in cold water and a 3mm in warm water. The person in a 7mm that I took to 10 pounds was much smaller than you. Still, I suspect you could drop a few pounds. We are all a little different. I know some excellent divers who need more weight than one would expect.

 

[Colliam7]

However, to achieve a horizontal position in the water, I moved my weight belt high up on my torso (think of old man/nerd pants). Is there a BCD out there that will hold weights in the upper part of the jacket? FYI - I had 6 lbs in each BCD pocket, 10 lbs on my weight belt & 2 lbs on my tank strap. I was diving in warm salt water with a 3mm full wetsuit. I'm about 6'1" & 230 lbs, average build. Or is there another solution?

I will not berate your PPB Instructor for the amount of weight you ended up with. It does seem to be a bit more than the average diver would need, but I wasn’t there for the class, I don’t know what factors went into the weight determination, etc. It is inappropriate for me to second-guess that instructor.

Instead, your specific question involves the distribution of weight and here are some comments. You are already thinking along the correct lines – move the weight ‘up’, from the waist toward the head. That is the key. Where is you physiologic center of lift? Your thorax / lung cavity more often than not. We repeatedly emphasize to students / divers that the goal is to learn to control buoyancy with breathing, rather than adding / purging air to / from the BCD. There is a reason for that – your lungs are the best means of fine tuning buoyancy. Should it come as any surprise that your body resists horizontal trim IF the center of weight is lower (on the waist, or in integrated weight pockets at the bottom of the BCD – i.e. more toward the legs) than the center of lift?

Some options:

1. A metal backplate, worn next to the center of lift. A stainless steel plate weighing 6 lbs, worn essentially adjacent to the center of lift is a good start. Most jacket BCDs don’t provide that, many back-inflation BCDs don’t either, by the way.
2. A steel cylinder. Again the steel cylinder puts weight in a position adjacent to your center of lift.
3. Additional weight placed around the cylinder valve. A couple of ankle weights wrapped around the valve, in such a way that they do not interfere with manipulation of the valve, is a possibility.
4. Trim weights placed in pockets on the cylinder cam bands. You mention you had 2 lbs on the cam bands. If you were using cam band pockets, I would shift up to 8 lbs from the waist to those pockets, not just 2. For BCDs with two cam bands (optimal, as opposed to only one band) the pockets should go on the upper bands.
5. Weights threaded on the shoulder straps of (some) BCDs. This doesn’t work well with jackets BCDs, it is a better option with back inflation units. But, you can either thread them onto the straps (OK, but cumbersome) or tie-wrap them to the straps (easier).

I firmly believe a good diver can achieve good trim with a jacket BCD, or a back-inflation BCD, whether that is a metal backplate or not. Equipment does not make the diver. But, there are equipment configurations that make achieving that optimal trim easier. I prefer to minimize the inherent positive buoyancy of my BCD (many / most BCDs are far too 'floaty', have needless padding, etc.), so I use a metal backplate. That works for me, it may not be best for you.

One other observation based on my experiences with a number of divers in various courses: when most divers feel that they are in good horizontal trim, in fact they are still a bit ‘head high’. When they are in good horizontal trim, they often feel they are a bit ‘head low’. Achieving good trim is a matter of practice, gear ‘tweaking’, and experience. Good luck as you progress.

 

[krbailey]

I will not berate your PPB Instructor for the amount of weight you ended up with. It does seem to be a bit more than the average diver would need, but I wasn’t there for the class, I don’t know what factors went into the weight determination, etc. It is inappropriate for me to second-guess that instructor.

Instead, your specific question involves the distribution of weight and here are some comments. You are already thinking along the correct lines – move the weight ‘up’, from the waist toward the head. That is the key. Where is you physiologic center of lift? Your thorax / lung cavity more often than not. We repeatedly emphasize to students / divers that the goal is to learn to control buoyancy with breathing, rather than adding / purging air to / from the BCD. There is a reason for that – your lungs are the best means of fine tuning buoyancy. Should it come as any surprise that your body resists horizontal trim IF the center of weight is lower (on the waist, or in integrated weight pockets at the bottom of the BCD – i.e. more toward the legs) than the center of lift?

Some options:

1. A metal backplate, worn next to the center of lift. A stainless steel plate weighing 6 lbs, worn essentially adjacent to the center of lift is a good start. Most jacket BCDs don’t provide that, many back-inflation BCDs don’t either, by the way.
2. A steel cylinder. Again the steel cylinder puts weight in a position adjacent to your center of lift.
3. Additional weight placed around the cylinder valve. A couple of ankle weights wrapped around the valve, in such a way that they do not interfere with manipulation of the valve, is a possibility.
4. Trim weights placed in pockets on the cylinder cam bands. You mention you had 2 lbs on the cam bands. If you were using cam band pockets, I would shift up to 8 lbs from the waist to those pockets, not just 2. For BCDs with two cam bands (optimal, as opposed to only one band) the pockets should go on the upper bands.
5. Weights threaded on the shoulder straps of (some) BCDs. This doesn’t work well with jackets BCDs, it is a better option with back inflation units. But, you can either thread them onto the straps (OK, but cumbersome) or tie-wrap them to the straps (easier).

I firmly believe a good diver can achieve good trim with a jacket BCD, or a back-inflation BCD, whether that is a metal backplate or not. Equipment does not make the diver. But, there are equipment configurations that make achieving that optimal trim easier. I prefer to minimize the inherent positive buoyancy of my BCD (many / most BCDs are far too 'floaty', have needless padding, etc.), so I use a metal backplate. That works for me, it may not be best for you.

One other observation based on my experiences with a number of divers in various courses: when most divers feel that they are in good horizontal trim, in fact they are still a bit ‘head high’. When they are in good horizontal trim, they often feel they are a bit ‘head low’. Achieving good trim is a matter of practice, gear ‘tweaking’, and experience. Good luck as you progress.

Thanks for the response. I thought about putting more weight on the cam band but I was using a rental BCD with AL 100 and there was barely enough extra strap to hold a 2lb weight. With my arms extended, I felt like I was slightly head down so I think my trim was good.

As to the overweighting - I thought my instructor did a good job. We spent over 2 hrs adjusting my gear and doing drills. I can't explain why I was unable to submerge with 20-22lbs. I believe I started with 18 lbs and I just floated at the surface. I completely exhaled and pulled all of the dump valves as well as the inflator hose. With more experience/dives, I'm sure I will be able to drop weight. The goal is to improve with every dive.

 

[Yellowdog]

There is a big difference between a new 7mm w/hood in cold water and a 3mm in warm water. The person in a 7mm that I took to 10 pounds was much smaller than you. Still, I suspect you could drop a few pounds. We are all a little different. I know some excellent divers who need more weight than one would expect.

Is there a difference in the weight needed in different water temperatures or just using different mm wetsuits?

 

[tbone1004]

there shouldn't be, though in cold water you typically don't flush your suit out quite as well so there tends to be some residual air pockets left in the wetsuit which doesn't help matters. That being said, it's still a lot of lead, so with a 3mm you just weren't doing something right if you needed that much weight, unfortunately it isn't surprising, but there's all sorts of little things that can lead to an ineffective weight check. Hopefully you can get with a good mentor in your area that can help you quite a bit more than that instructor did.

 

[cascas]

If bp and wing are no option try moving your tank up. That will be much more comfortable than wearing your weight belt nerdy style.