Question about weighting in a thick suit

[elan]

Well, after playing around trying to get my weighting right in a 3mm shorty, a 3mm full, and then a 5mm full, I find myself off to complete AOW in a cold fresh water lake wearing a 7mm full with a 7mm hooded vest over the top.

Am I going to need 50 pounds to get me under

It took 22 pounds to keep me down in salt water wearing the 5mm (and my guess is I should have started with 4 extra pounds to compensate for air usage).

I know fresh water will give me a little bit of a break, and I may have to try a couple different configurations to get it worked out, but what do y'all think would be a good starting weight to try? I do have a bit of "natural buoyancy". I weigh 160 or so at 5'6".

Fresh water would give you a bout 6lbs of a break. And the 7mil will likely be about 2lbs more buoyant. so you subtract 4 from your 22lb and you get 18lbs so if you got 22lb with a full tank add another 5lbs for an aluminum tank. So you will get about 23lbs. Add another 2-3 pounds in the beginning and then see if you see you are overweight take some away.

 

[Bubbletrubble]

Thanks everyone. I'll discuss it with my instructor but will most definitely need to bring more weight than what I own. I'm trying to not have to rent any gear but the tank for local dives, and have purchased 20 pounds of lead so far (that stuff ain't cheap). I'll pick up another couple of 4 or 5 pound weights this week. I do have trim pockets on the back of my BD, and could reasonably fit my two 2 pound weights back there.

@TexasKaren68: Where to carry your ballast would be a great discussion to have with your AOW instructor.

Here's my take on it...
You should only load trim pockets with weight if it helps with your static horizontal trim. Put too much weight in trim pockets on many BCDs and you may find yourself with head-down/feet-up trim (inverted). That's not good. Start with all the weight on your hips (in weight-integrated pockets or on a weightbelt/harness). If you have head-up/feet-down trim, then gradually shift enough weight to the trim pockets so that you can easily get horizontal. A buddy or instructor should be able to help you with this.

I wonder if I should try to cram all the weight into my BC, or put some of it on a weight belt. Pros? Cons?

Personally, I like the idea of splitting up weight between a belt and the weight-integrated pockets. It means you can ditch just enough weight for whatever emergency situation you're in. This also mitigates becoming excessively buoyant in case of accidental ditching of a pocket or the belt. Moreover, attaching some weight to your person means that if you ever have to remove and replace your BCD at depth, you won't be floating up too much while your BCD is stuck to the bottom.

I don't like putting too much weight on a weightbelt because the belt tends to slip off of my waist during shore entries (surf, long walk). A rubber belt can help with this. Having hips also helps. I have a nifty DUI Weight & Trim harness.

Depending on how much lift your BC has, you might want some of the weight on a belt so that your rig will float on the surface without you in it. That may not be an issue but it's something you can calculate ahead of time.

@Blue Sparkle: The vast majority of recreational BCDs provide waaaaaay more lift than a diver requires. Many jacket BCDs I've used have 40+ lbs. of lift. Even if she required 25 lbs. of lead and she loaded all of it into weight-integrated BCD pockets, she'd still probably have plenty of lift. Consider that many jacket BCDs have +2 to +4 lbs. positive buoyancy (due to padding), a full AL80 is about -4 lbs. buoyant, and a reg setup is about -2 lbs. buoyant.

 

[Blue Sparkle]

@Blue Sparkle: The vast majority of recreational BCDs provide waaaaaay more lift than a diver requires. Many jacket BCDs I've used have 40+ lbs. of lift. Even if she required 25 lbs. of lead and she loaded all of it into weight-integrated BCD pockets, she'd still probably have plenty of lift.

Okay, I guess that particular consideration won't be necessary then -- 40# should certainly cover it (I didn't know what she was diving with for a BC)

 

[oly5050user]

Well, after playing around trying to get my weighting right in a 3mm shorty, a 3mm full, and then a 5mm full, I find myself off to complete AOW in a cold fresh water lake wearing a 7mm full with a 7mm hooded vest over the top.

Am I going to need 50 pounds to get me under

It took 22 pounds to keep me down in salt water wearing the 5mm (and my guess is I should have started with 4 extra pounds to compensate for air usage).

I know fresh water will give me a little bit of a break, and I may have to try a couple different configurations to get it worked out, but what do y'all think would be a good starting weight to try? I do have a bit of "natural buoyancy". I weigh 160 or so at 5'6".

Way too much weight..At 5'6"- 160 lbs you should be able to dive in a 5mm with no more than 12lbs of leads with a alum tank.In a 7mm suit you should wear around 16-18lbs.and that is for salt water..Steel tank less lead..I am 5'11" and 170 and use 6lbs in a 3 mm suit and 10lb in a 5mm..that is in salt water.Less lead in fresh water.

 

[spectrum]

I wonder if I should try to cram all the weight into my BC, or put some of it on a weight belt. Pros? Cons?

My BC only carries the weight I need on my upper body for trim purposes. the rest goes on a belt or DUI weight & trim harness.

First of all it avoids having your BC become an obnoxious beast this is important if you need to hand the rig off to a boat crew for instance. It also makes it a lot friendlier when doing a cylinder swap.

Secondly you have entered the realm of significant buoyancy from your wetsuit. If you ever need to get out of your rig underwater due to entanglement or other curiosities it is much easier if neither you nor your rig are massively buoyant. You can retain a grasp on the BC to hold you down but the freedom to problem solve can be greatly diminished. You may feel you have a buddy for these matters. However in limited visibility a buddy can be lost and you can find yourself solo confronting an issue in a heartbeat. Even if the likelihood of getting out of your rig is low you should be practicing this skill from time to time. Keeping considerable weight on your person will make the drilling safer and easier too.

Pete

 

[Blue Sparkle]

Way too much weight..At 5'6"- 160 lbs you should be able to dive in a 5mm with no more than 12lbs of leads with a alum tank....and that is for salt water

Are you sure that holds true for everyone? I'm proportioned similarly to the OP, and looking in my dive log for the last time I dived with an AL80 and a 5mm suit, I see that I wore just under 15# of combined ballast (BC + lead). This is including the ~6# to account for breathing down the tank (it sounds like you are including that in your figures as well).

With that amount of weight I need to exhale completely and do a bit of "active swimming" to get down the first 10' or so, until my wetsuit starts to compress. So I don't think I'm overweighted, or if so, not by a large amount (of course I'm always experimenting with less!) Also, my BC has virtually no inherent buoyancy, and the OP's might have.

(In comparison, with no exposure protection, I wear about 4# of weight -- integral to my BC -- plus whatever I need to compensate for the air I plan to breathe from the tank. That seems to correlate with the amount I add for the 5mm suit using Quero's rule of thumb of 1# for 1mm.)

Blue Sparkle

Edited to add: I'm not saying the OP would need the exact same weight as I do, but you just sounded so definite that there would be no way she would need more than 12# of lead with a 5mm/80 if she were in salt water.

Also, I see you are a really experienced instructor, so maybe I'm doing something wrong? If so, I should not be advising but should instead be figuring out what I need to correct :blush:

 

[tac747]

I am no expert but I would start at 22 pounds. I use 22 pounds in salt with 7mm and 12 pounds in fresh with a 7mm She said in salt water with 5mm she needs 22 pounds. In fresh water I cant imagine it would take more than 10 pounds to sink a hooded vest but if it did I would still rather be light and add more to start the weight check than be heavy but I am fairly new so I may be wrong

 

[spectrum]

I cant imagine it would take more than 10 pounds to sink a hooded vest but if it did I would still rather be light and add more to start the weight check than be heavy but I am fairly new so I may be wrong

Actually it is 11 for that item.

With regard to preferring to be under weighted you are wrong. A diver 2, 4, even 6 or more pounds can still safely dive. It may not be elegant but it's manageable. If under weighted there comes a point where you are going up, ready or not.

 

[tac747]

I was refering to doing the weight check, not an actual dive when I said I would rather be light than heavy. The way i did it was with a tank and approx 700# I put in what weight i thought I would need then went out to about 6-8 feet of water with my buddy holding my extra weight. If I was light he would hand me small amounts until i was right then I did the same for him. Once we got our weight down then we got the full tanks and and did the dive.

 

[Blue Sparkle]

But it sounds like tac747 was saying he/she would rather be light to *start* the weight check (i.e. just before making the dive). Doesn't that seem right if you are doing a weight check? You could start to the light side and then add weight gradually until you "pass" the weight check, then add weight in the amount of gas your tank holds, and then go diving? (I suppose you could start heavy and then remove weight too, but is there a problem doing it the way tac747 suggests?)