Weight distribution with changing gear configurations

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Cthippo

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Bellingham WA
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I'm finding that in warm (ish) fresh water I need so much less weight that I could move all of it into my BCD. Question is, is this a good idea?

When I did my initial open water training it was in the sound and I was diving a 7mm with 30 lbs of weight divided between a weight harness (10 lbs each side) and my BCD (5 lbs each side). Now that it has warmed up some I am diving in the lake with my 3/2 wetsuit and am slowly removing weight to see what I need. At the end of today's dive I completely emptied my BCD pouches and established that at least in this configuration I can get by just fine with only 20 lbs even with an empty cylinder. My question is, would I be better off to move that weight into the BCD and leave the harness in the bag?

Also, do you change weights when you change cylinders? Ifyou switch from a steel 95 to an AL80 (or even an AL40 for quick tasks) do you change your weight amount and configuration?
 
20 lbs still sounds like a lot for a 3/2 wetsuit and fresh water.

Yes, I would adjust lead for a given configuration IF POSSIBLE. In order of my preference: ideally weighted, slightly over, slightly under. If I'm underweighted (e.g., charter ran out of lead), I might plan a shorter dive to keep more of the gas weight on me.
 
I'm finding that in warm (ish) fresh water I need so much less weight that I could move all of it into my BCD. Question is, is this a good idea?

When I did my initial open water training it was in the sound and I was diving a 7mm with 30 lbs of weight divided between a weight harness (10 lbs each side) and my BCD (5 lbs each side). Now that it has warmed up some I am diving in the lake with my 3/2 wetsuit and am slowly removing weight to see what I need. At the end of today's dive I completely emptied my BCD pouches and established that at least in this configuration I can get by just fine with only 20 lbs even with an empty cylinder. My question is, would I be better off to move that weight into the BCD and leave the harness in the bag?

Also, do you change weights when you change cylinders? Ifyou switch from a steel 95 to an AL80 (or even an AL40 for quick tasks) do you change your weight amount and configuration?
I take off 6 pounds when moving from AL80 to HP100.
 
20 lbs still sounds like a lot for a 3/2 wetsuit and fresh water.
Agree. Just as 30 sounds too much with a 7mm.
What you were carrying when you did your initial training is almost irrelevant...you were quite possible overweighted....and with some experience you tend to drop weight anyway.
 
I always told my students if they needed more than 10-12 lbs of lead to put it in at least 2 different systems. For me, if diving a jacket BC, that meant the BC and a weight belt. Using 20 lbs as an example, I'd put 3s in each bc pocket, 4s in the trim pockets, and 6 on the belt. With the idea that if I ever needed to drop lead anywhere other than the surface, I could drop the least amount to start to get positive and still control my ascent.
I hope you didn't practice dropping all your lead at once. That's dumb and rarely necessary.
Also, the buoyancy characteristics of steel vs aluminum mean you absolutely do change the amount of lead you are using. Your instructor should have spent a lot of time on proper weighting and discussing the changes needed going from one type of exposure protection to another and the effect of different cylinders.
Using the above example, that's what I would need with an al80 in my 5 mil farmer john freediving suit (10 mil on the core) in freshwater. If I used one of my steel lp 95s I could drop 6 lbs of lead from what I needed.
 
You certainly could move it. But 20 lbs in a BCD along with the tank is a lot of weight to deal with above water, so I'd say it depends on how you get into the water. For example, if it's a shore dive and you can gear up on a table, it would probably be fine.

And yes, you will need less lead when diving a steel tank than a similar sized AL tank. The amount you can take off is the difference between their empty buoyancy measurements. For example an AL80 is about 3 pounds positive when full and a Faber steel LP95 about 1 pound negative, so you'd get to remove 4 pounds of weight.

You can see a chart of the specs for different tanks at SCUBA Cylinder Specifications – Huron Scuba, Snorkel & Adventure Travel Inc. PADI 5 star IDC in Ann Arbor, MI
 
Agree. Just as 30 sounds too much with a 7mm.
What you were carrying when you did your initial training is almost irrelevant...you were quite possible overweighted....and with some experience you tend to drop weight anyway.
Going from a 7mm to a 5mm -- all other things being equal -- usually means dropping at least 5 lbs. Going from a 5mm to a 3mm means at least another 5 lbs. So your dropping 10 lbs is a good first iteration of going from 7 to 3/2....although 12 lbs seems more likely. A 7mm first guess weight need would be 20 lbs, not 30.
 
30 lbs in saltwater with a 7 mm suit does not sound anywhere equivalent to 20 lbs in a 3/2 in freshwater! I would be surprised if you can not drop 20 lbs of the 30.
 
30 lbs in saltwater with a 7 mm suit does not sound anywhere equivalent to 20 lbs in a 3/2 in freshwater! I would be surprised if you can not drop 20 lbs of the 30.
My earlier point was that dropping 10 lbs is about right, but it is starting from 30 that is the problem!
 
My Q&D weight calc: AL80 is about +3.5 lb (empty fresh water*), 500 psi reserve air is -1 lb, regulator is -2 lb, alu backplate/wing is -1.5 lb, my XL 3mm suit is +5.5 lb at the stop (based on +8 lbs on the surface), my fins are -1 lb. Add it up and I need about 4 lbs of lead to make everything neutral. (I'm approximately neutral when nekkid.)

Ideally your OW training would have gone over something like this, but hopefully you can adjust the above to fit your particular situation. Tip: a luggage scale comes in handy to directly measure buoyancies.

(*) Faber AL80 tanks are spec'd at +4.4 lbs in salt water. Adjust for fresh by subtracting 2.4% of the *dry* weight (about 35 lbs with valve) due to fresh water being less dense.

ETA: I put the 4 lbs on my tankband for better trim and don't worry about needing to ditch anything. A normal breath makes me positive on the surface with a full tank and empty/busted wing.
 
https://www.shearwater.com/products/peregrine/

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