L13
Contributor
I found the same thing.
How accurate do you guys find DiveBuddy.com for their weight calculator?
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GreggS
Contributor
Same here. It shows I should be using 15 lbs. in fresh water with a 3mm wetsuit and 80cf aluminum tank. I'm perfectly weighted at the end of a dive with 500 psi with 8 lbs of lead when rigged this way.
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Dive Buddy overestimated the weight I use by 70-20%, worst with a full 3mm wetsuit, least with a full 7 mm wetsuit
I often think it would be helpful when discussing weigh required to detail what specific equipment is being used, and in fresh or saltwater. For example, I have a three sets of fins: Mares X-stream fins with rubber bungee (positive buoyant), a pair of Atomic Smoke on the Water with spring straps (a little negatively buoyant), and a pair of Apollo Bio pro fins with spring straps (sink like a rock). Depending on which fins I am wearing, my weight requirement could swing 3#. Same scenario with my HOG TBCS soft plate/32# wing vs my Zeagle Covert with 32# bladder. The HOG system needs 3# to sink, the Covert less. If I was using a metal plate, I would include that weight in my total weight requirement. Also, my SP MK17/S555/R395 with AI computer and backup console are heavier than most lighter weight gear I have used in the occasional gear rental. Finally, I have a new Bare Reactive 3mm and 5mm, and they take considerably more weight to sink than my old, compressed Bare Elastek wetsuits. My point is that when someone asks me what weight I need, I think to myself "It depends" and tell them what I need for that dive with the gear I am using, but those types of details don't seem to make it into the typical SB discussion on "how much weight do I need?"
OP
Well let me run my gear through the excel doc and see what I get. I know all my gear so I can get all the info
johndiver999
Contributor
This is silly, If you vented the BC and didn't have air in the wetsuit, then you need more lead. Don't think a spreadsheet or internet personalities are going to give you more relevant information. At 287 with a double layer 7 mm suit, you need a lot of lead.
You have already determined that you need 15 lbs with a bathing suit, so 38 lbs seems very reasonable to me for a guess at freshwater. You are going to need 7-8 lbs more for saltwater. You may want to distribute weight on a weightbelt and in pockets etc. on BC. You are also a good candidate for a larger, more dense steel tank, assuming you can handle the extra weight on the boat.
If the suit is brand new, you may find that the buoyancy drops a good bit after a few days of diving.
The real value (in my experience) with the Buoyancy calculator spreadsheet is for when things change. It breaks out not just what you need, but which part of the equation it comes from. Once you have weighting sorted for one set of conditions, it will accurately predict changes (salt to fresh or vice versa, AL80 to HP100, different exposure protection, you name it). No pure calculation will nail all the vagaries of the human condition first try, but once the personal buoyancy (that 15 lb in a swimsuit) is accounted for the calculator save a massive amount of trial and error.
Respectfully,
James
KenE
Contributor
Based on your experience, I would add 4-6 lbs, you will need at least two to get down and the other 2-4 to offset empty tanks at the end of the dive. Many forget this and can't hold a safety stop on empy tanks. Then, when on empty tanks at safety stop start handing weight in one pound increments to your buddy. When you start to rise, take one back and that is what you need for that configuration. I will note that a new wetsuit will lose bouyancy after several dives. I have a similar body size/style and dropped two pounds after the wetsuit was 10-12 dives older. Maybe I lost a pound or two as well.
OP
Thanks I an loaded with 38 right now we will see this weekend. Right now I have my 4 extra pounds in the general pockets of my BCD and the ditch weights and trim pockets are that capacity. If 38 seems right I most likely will move the 4 extra lbs to the tank straps. Thanks for your advice I appreciate it.
CT-Rich
Contributor
Sometimes the number is the number. 287 makes you a big guy. I wear a 3XT wetsuit and weigh 240. Every couple of years someone says I should shed some lead, I must be over weighted. now and again I will listen and think I should shed a couple of pounds. I end up actively swimming head down at 30' to finish the dive. I need about 28 lbs with a back zip 5mm and a steel tank. Your number is your number. It might be the wetsuit needs breaking in or it might be you have air trapped some where.
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