Ditchable weights...are they needed and is there a minimum?

[OH-JJ]

OK to the OP's problem as has been said, It is you r tank. Heisire's Are insanly negative for their size.

as for ditchable weight. I dive double PST 104's with my SS plate, I need no additional weight. Even though I can and have swam my rig off the bottom with an empty wing, I carry cheap insurance with me... my lift bag. If you know how to use it it will get you up in a controlled fasion. Personally, the idea of an uncontrolled ascent from 60+ft scares me to death, let alone a 120+ft with deco obligations. And yes for real dives I wear my drysuit, but for shallow stuff in warm water I like my wetsuit.

 

[ItsBruce]

... Someone dies somewhere in the world with this combination every year, ....

I felt compelled to respond to this observation before reading the entire thread:

1. This is probably accurate.
2. More than one person dies every year from having a vending machine fall on them.

Since humans are not inherently able to swim deep under water for extended periods, doing so entails certain risks. Diving requires managing these risks.

To dive safely, a diver must be able to hold position at a safety stop. Otherwise he or she risks a runaway ascent. That means being neutral with an empty tank and empty BCD. Everything else should be calculated based on this.

As depth increases, one's wetsuit becomes less buoyant. Therefore, one must rely on one's BCD to remain neutral at depth.

A BCD failure at depth means one cannot remain neutral without dumping weight. However, that means an ascent problem as one surfaces.

Whether one can swim their rig without the benefit of a BCD is a question of personal capability. The good news is that it does not require a huge change in depth before wetsuit buoyancy begins to help.

If one suffers a BCD failure at depth and cannot swim their rig, then one has no choice but to dump enough weight to swim their rig and then deal with what becomes an emergency ascent.

Changing direction slightly, let me mention something about lift capacity. Does one need more lift than is necessary to lift off the bottom? Assume one's rig is -5 and one wears 15 pounds of lead. Does one need more than 25 pounds of lift? If one's rig is neutral and one wears 20 pounds of lead, does one need more than 25 pounds of lift? If one's rig is +5 and one wears 25 pounds of lead, does one need more than 25 pounds of lift?

Note: the weight is needed to counter the buoyancy of the wetsuit at the surface and the wetsuit should be considered to have 0 buoyancy at depth, so the BCD must compensate for that.

 

[Doc Harry]

The Scuba Police have been here, deleting stuff....

 

[OH-JJ]

I felt compelled to respond to this observation before reading the entire thread:

1. This is probably accurate.
2. More than one person dies every year from having a vending machine fall on them.

Since humans are not inherently able to swim deep under water for extended periods, doing so entails certain risks. Diving requires managing these risks.

To dive safely, a diver must be able to hold position at a safety stop. Otherwise he or she risks a runaway ascent. That means being neutral with an empty tank and empty BCD. Everything else should be calculated based on this.

As depth increases, one's wetsuit becomes less buoyant. Therefore, one must rely on one's BCD to remain neutral at depth.

A BCD failure at depth means one cannot remain neutral without dumping weight. However, that means an ascent problem as one surfaces.

Whether one can swim their rig without the benefit of a BCD is a question of personal capability. The good news is that it does not require a huge change in depth before wetsuit buoyancy begins to help.

If one suffers a BCD failure at depth and cannot swim their rig, then one has no choice but to dump enough weight to swim their rig and then deal with what becomes an emergency ascent.

Changing direction slightly, let me mention something about lift capacity. Does one need more lift than is necessary to lift off the bottom? Assume one's rig is -5 and one wears 15 pounds of lead. Does one need more than 25 pounds of lift? If one's rig is neutral and one wears 20 pounds of lead, does one need more than 25 pounds of lift? If one's rig is +5 and one wears 25 pounds of lead, does one need more than 25 pounds of lift?

Note: the weight is needed to counter the buoyancy of the wetsuit at the surface and the wetsuit should be considered to have 0 buoyancy at depth, so the BCD must compensate for that.

You need enough lift to get you off the bottom with your max gear, and float your head above the water with full tanks. That's the minimum

 

[Oside Jimc]

So for clarification:
I have 30lbs of lift on wing. It is a DSS 30 LCD.
BP is about 5lbs.
BP has another 5lbs screwed in.
My weight belt has 14lbs.
I weigh 120 and wear 2 piece wetsuit.
No other neg buoyant equipment.

I dive an almost identical rig (LCD30, SS BP, add on plate weight), differences are I dive a HP100 which would remove about 5lbs from my weightbelt, and I have a medium BP while I assume you dive a small (so 2 more lbs off my weightbelt). When I dive I use 8lbs on my belt, if you add the 7 that would require I use 15 for an AL80 + small plate, that in only 1 lb more then you use, but I'm a 200lb guy with "extra bioflotation" (plus I'm wearing a 7mm full w/hood, gloves, and booties), so how sure are you that 14 is the right amount for an al80? When I started with my BP/W I tried 16lbs on the belt and found myself in a similar situation where I could barely keep my face above water on the sirface swim. If you are already overweighted that toad of a tank could have pushed you over the edge. I'd think hard about moving to a better choice of tank (HP100?), and at the very least do some careful weight checks with an al80 because I do not see how on earth a slim woman would need 14 lbs with a BP + add on weight.

For a gently sloping beach dive, I agree, there is little risk with a thick wetsuit and steel tanks and tons of other nonditchable weight, since you could always simply crawl back up the beach underwater if you needed to.....................................................
The latest case was over the past weekend in San Diego, according to some of the other dive boards, and here:
http://www.scubaboard.com/forums/3879674-post1.html

There is no indication whatsoever that overweighting had anything to do with this accident and inferring that it did is totally spurious. In fact all indications are that this tragedy is just a foolish dive "plan" gone horribly wrong, in fact La Jolla Shores is just what you describe, a gently sloping terrain you could crawl you way up.

 

[OH-JJ]

I'd think hard about moving to a better choice of tank (HP100?), and at the very least do some careful weight checks with an al80 because I do not see how on earth a slim woman would need 14 lbs with a BP + add on weight.

Jim are ya married? Because a woman will take that two ways...
1. she actually needs the weight because she is fat.
2. She is skinny but unskilled so needs the extra weight....

Tip: when it comes to women and there weight whether weight belt or other.... keep thy trap shut

 

[OH-JJ]

Of course I think Neither is the case... She just made the mistake of using Faber's in stead of PST tanks

 

[Bubbletrubble]

For a gently sloping beach dive, I agree, there is little risk with a thick wetsuit and steel tanks and tons of other nonditchable weight, since you could always simply crawl back up the beach underwater if you needed to.

And for shallow diving, the suit compression simply does not become an issue, either.

The walls and canyons are where thick wetsuits can be lethal, however. Someone dies somewhere in the world with this combination every year, although normally it is caused rather by going too deep, getting narcosis, using up or dumping air, and then spiralling away. The latest case was over the past weekend in San Diego, according to some of the other dive boards, and here:

http://www.scubaboard.com/forums/3879674-post1.html

@nereas:As a point of clarification, the recent San Diego fatality to which you were referring did not involve the "combination" of thick wetsuit and steel tank. The victim wore a 7mm wetsuit but his single tank rig had an AL80 on it. This fact has been verified by Lifeguard sources and the LDS renting the tank. At present, we have no information regarding his weight configuration, the functioning of his BCD, or the status of his ditchable weights once the body was recovered.

@divechk: Please do a proper weight check with your "new" Heiser tank. Others here have pointed out that you are likely overweighted. You may have been overweighted even when you were using an AL80 (despite being able to float at the surface with a fully inflated wing). This may sound obvious, but first establish your weighting requirements, i.e., how much total ballast you need...then determine distribution of that weight for proper trim and how much of that weight you want to be ditchable.
If you're not sure how to do the weight check, please find an experienced diver or instructor to help you out. Divers need to do them whenever they change their gear configuration (tank, drysuit undergarment, exposure suit, BCD, etc.). When properly weighted, you'll find diving more comfortable/enjoyable.
I'll be interested to hear the results of your weight check. Please update this thread when you get the chance.
Have fun and dive safe.

 

[Supershark]

I have read this thread at length, and become very confused. People seem to have been saying that they add air to their BC/Drysuit/Wing to aid ascent. As an instructor I teach people to vent air whilst ascending. If properly weighted anybody should be able to swim to the surface without having to add air.
I wear a 5mm full length wetsuit, pro2000 bc, and dive with zero weight. Is it being suggested that I should still have weight to remove? Please explain to me as I don't understand.