I never really see anyone try to talk them out of so much weight. Is this because:
1.) It doesn't work so why try.
2.) Not your job.
3.)You do try discreetly but they don't listen.
1. It does work.
2. It IS our job.
3. Sometimes - discreet or not - they think they know better.
Personally, I'm ALWAYS trying to talk people into dropping some weight. My own non-scientific estimate would that 80% of people diving dive over-weighted. Now if it's just 2 pounds or so, maybe not a big deal. But if it's 10 pounds, oh my. I try to encourage them to do the next dive with 2 pounds less than they're wearing, and see if they can have an empty BC at the end-of-dive safety stop and hold their position without kicking. If they sink, take off 2 more pounds. Keep doing that until you reach a point where you took off 2 pounds too much. (And before anyone scream "uncontrolled ascent!!!" realize your lungs hold roughly 10 pounds of air so just by exhaling a bit and never really filling up your lungs, you can compensate for being under-weighted at the final safety stop.)
It also makes a difference as to whether you're diving warm or cold water. In warm water, assuming you're wearing a skin or light/thin wetsuit, there's very little to compress, so your buoyancy/weight-needed changes little with depth. However, in cold water, you're likely wearing a 7mm with hood and gloves and there are significant buoyancy changes as you descend. Which means if you're over-weighted to start with, you're REALLY over-weighted at depth. In fact, in cold water, I advocate UNDER-weighting yourself a bit because as you descend, the wetsuit compression will compensate for the under-weighting.
The real question is: Why do people over-weight themselves so consistently? And the answer IMHO is it's because we, as an industry, have taught them to dive that way. Back in basic class or on a checkout dive with five or six people already on the bottom, when someone can't descend they aren't told "Hey, let's take 15 minutes to do some really good weight-checking for you." What they're told is, "Throw another 5 pounds in your pocket and let's go." So that becomes their solution to any descent issue. Add another 5 pounds.
People are also lousy at really dumping ALL the air out of their BC. I've seen plenty of folks over the years with air in their BCs struggling at the surface and calling out for more lead. I've said for years "I need more weight!!!" is the cry of the chronically over-inflated.
True story to end with. It's 1988 and I'm diving in Cozumel. GF and I surface . inflate BCs, and wait for boat to come pick us up. Two others from our boat surface right next to us. Guy has his BC fully inflated, is kicking, and can barely keep his head above water.
"How much weight are you wearing?" I ask.
"25 pounds," he gaspingly replies.
"Why so much?" I ask.
"Because that's what I need at home," he says.
"Where's home?" I ask.
"Michigan," he says.
"Do you wear anything there that you're not wearing now?" I ask.
And now there's a pause and you can see he's REALLY pondering this.
"Do you mean a wetsuit?" he asks.
"Yes," I say. "Do you think that makes a difference?"
And again you can see him really pondering, and then you see a light bulb go off over his head as our boat comes by.
"I'll bet it does!!! I'll bet I could take off 2 pounds," and he was very excited about this revelation.
"Maybe even a little more," I suggested.
He came to me at the end of the week and very proudly proclaimed that he was able to drop 8 pounds from what he'd been diving with. I congratulated him and suggested he might even be able to drop a bit more but at least it was a step in the right direction.
- Ken
