Why is overweighting a bad thing?

[jiveturkey]

scubaspider once bubbled...
how do you know when u have the right weight configuration. Techinally I would need 23lbs in my belt if you follow the 10% +5 rule but when I did that I couldnt get to the bottom....so i added 2 more lbs. and i have problems staying off the bottom...(probably my bouancy control problem)

But still, how do you know when you have the right weight combo??

mmmm....23lbs is about 10 or 12 kgs methinks. This should have been covered in your open water class. With your tank almost empty (50 bar/500psi) and an empty bc, you should float at eye level while holding a normal breath of air. If your eyes are below the water, you have too much weight. If your chin is well above water you don't have enough.

Just because you couldn't get down doesn't mean you didn't have enough weight. Control of your breathing means a lot here too.

Try this now at your computer: Breath out normally and pause for a second at the end of this breath. Now push harder to get the rest of the air out of your lungs. There's quite a bit left right? Same thing when you're trying to get down in the ocean. I bet you still had a lot of air left in your lungs when you couldn't get down on 23lbs.

If you're anxious or out of breath it's going to make this more difficult. Try to relax and breath out until you begin to sink.

 

[GlockDiver]

Too much weight makes for a more difficult hike to/from the entry/exit point.

 

[cornfed]

More weight means it hurts more when you drop your weight belt on your foot.

 

[Don Burke]

Spider,

You are weighted correctly when you can hold your shallowest stop (I use 10 feet) with your minimum pressure (I use 400psig) in your back tank(s) and no air in your BC. Period.

What happens on the surface isn't an issue. The "10% plus 5" rule and the "eye level on exhale at the surface" rule are just to get you close enough to fine tune your weight. It won't be exact.

Both of the above rules don't properly account for neoprene compression. Getting in the water and going to your shallowest stop depth takes care of that.

The answer is to get in the water and figure it out. Don't forget to compensate if you are dealing with a salinity change.

If you're having problems getting under while properly weighted, exhaling while you kick down should fix it. Giving the wet parts of your gear a chance to flood may also be needed.

 

[Don Burke]

Each extra pound puts an additional 27 cubic inches of air in your BC. That makes your buoyancy control trickier, especially at shallow depths and increases your workload.

 

[Custer]

Don Burke once bubbled...
Each extra pound puts an additional 27 cubic inches of air in your BC. That makes your buoyancy control trickier, especially at shallow depths and increases your workload.

For myself, I find the exact opposite to be correct.

 

[ERP]

Custer once bubbled...


For myself, I find the exact opposite to be correct.

What do you mean by the exact opposite?

The original post is accurate,

more weight => more Air in the BC to compensate => more change in bouyancy with depth

I was just thinking about this earlier today, I did my first doubles dive this morning and I was surprised how much more I was having to compensate for depth changes, simply because I required more air in my wing to compensate for the increased weight of the air I was carrying.
I was probably overweight aswell since I just made a random guess at how much weight to carry.

 

[pipedope]

Being overweighted is a bad thing when the crane cannot lift the diver stage out of the water.

Oops,,,, .... back to FUN diving.

Being overweight is bad because of the extra air in the BC that has been covered already but you must also be able to swim up your gear from depth with NO AIR in the BC as a safety measure.
BCs can and do leak or get punctured.

Being underweight is also no a good thing as it makes control at the safety stop dificult and makes a very slow surfacing move from 15' to the surface much more dificult.

It is best to have the right weight, and remember that amount will change with changes in water density. Like diving is salt or fresh water.

 

[Don Burke]

Being overweight is bad because of the extra air in the BC that has been covered already but you must also be able to swim up your gear from depth with NO AIR in the BC as a safety measure.

That doesn't alway work. If I'm in my 5/3 wetsuit with double 80s, I've got ten pounds of air and about ten pounds of neoprene compression to deal with at 100 feet. I'm not going to depend on my regulator keeping up with me under such a load, although I'm sure it could.

Making the correct amount of weight ditchable is the answer. Overall weight stays the same.

 

[Custer]

ERP once bubbled...



What do you mean by the exact opposite?

The original post is accurate,

more weight => more Air in the BC to compensate => more change in bouyancy with depth

I was just thinking about this earlier today, I did my first doubles dive this morning and I was surprised how much more I was having to compensate for depth changes, simply because I required more air in my wing to compensate for the increased weight of the air I was carrying.
I was probably overweight aswell since I just made a random guess at how much weight to carry.

The exact opposite.

That's english for "The exact opposite".

He said- "That makes your buoyancy control trickier, especially at shallow depths and increases your workload. "

Especially in shallow depths, with a few extra pounds, I'm more stable.

I find it hard to believe that you'd think a Los Angeles class sub is more stable than a Ohio class sub.

But it could be me.