View Full Version : Ditchable Weight or not ?
Having recently changed from BC to single tank wing, I went in the pool tonight to do a weight check. With 2kg lead I sank to the bottom on breathing out but rose to the surface on breathing in, I am now assuming that I only now need to carry the 2kg on my belt ( was in full dry suit kit with 30 bar in 15L cylinder).
What I cant work out is that if I add a 3L pony (ali), should I lose any of that 2kg weight.
I am assuming that the weight of the pony on top of the 2kg is making me negative by the weight of the pony. However if I lose some/all of the 2kg weight to compensate for the pony then I lose my ditchable weight in an emergency.
Any tips, ideas or advice ?
toptribefan
10-07-2008, 01:34
Not a setup I've used but doesnt the pony become your ditchable weight?
Surely if your already breathing your pony and get into the sort of trouble that you need to ditch weight, youre headed for the surface in a hurry anyway.
I'll follow this with interest as I'm about to head in this direction and this hadnt crossed my mind yet.
Michael Purcell
10-07-2008, 02:32
First off I have no opinion on what is best for you. That is something you need to think about. Gathering information as you are doing is a good start.
When I did my open water in a 7mm + 7mm wetsuit I had a 40lbs weightbelt.
In that situation I believe having at least some of that weight separated from the belt is important (personal opinion)
When I go snorkeling I will often wear 4lbs around my waist with no wetsuit.
My point is when we are talking about 2kg (and you are wearing a single, so one would hope limited deco) personally I would not be worrying about the 2kg either as a belt or non-ditchable weight. If you can't swim up a 2kg weight you have bigger problems.
A thing to keep in mind is the stage will become lighter as you breathe it down. Shouldn't be an issue but you might want to try the same thing with an empty stage.
Was it a neoprene suit or a membrane and did you have a undersuit or
thinsulate?
Plus did you have hood, gloves, torch, reel etc. etc.
A pool check is a good start, but i'd always assume you are too light,
then do a full buoyancy check at start and end of dive, with FULL kit.
You'll then know what (if any) you need to take off.
Was it a neoprene suit or a membrane and did you have a undersuit or
thinsulate?
Plus did you have hood, gloves, torch, reel etc. etc.
A pool check is a good start, but i'd always assume you are too light,
then do a full buoyancy check at start and end of dive, with FULL kit.
You'll then know what (if any) you need to take off.
Membrane suit with Fourth Element xerotherm Arctics (yes I did sweat a little) however no hood or gloves.
Didnt wear anything else but I only normally carry a small plastic reel and hand held torch which are relatively light.
What I cant work out is that if I add a 3L pony (ali), should I lose any of that 2kg weight.
Empty ali cylinders are normally about neutral or slightly positive, this will be off set by the regulator. So you will probably be about the same carrying it as not.
Scaramanga
10-07-2008, 09:20
Surely you need to take into account the affects of salinity, unless you will just be doing freshwater dives?
Nigel Hewitt
10-07-2008, 09:27
Surely you need to take into account the affects of salinity, unless you will just be doing freshwater dives?Well in theory it is add 2.7% to your total weight including existing lead.
But in fact 3Kgs/6lbs is always near enough pretty much regardless of kit.
Ditchable weight is for other people when you need to pin them to the surface. I only use it RIB diving so I can hand off some of the weight and reduce the lump that has to be haulled over the side. Ditiching somebody's weight at depth is only done to recover the body. There is always a better way.
Scaramanga
10-07-2008, 12:16
Ditiching somebody's weight at depth is only done to recover the body.
Or to create one.....:eek:
Nigel Hewitt
10-07-2008, 12:57
Or to create one.....:eek:
I fear so. Without putting enough detail in to be identified there was an incident I read when a buddy dropped an unresponsive divers weights and the cause of death was given as a lung over expansion. (not UK)
So he was alive when they sent him up.
No. I don't know what I'd do if I had 40 minutes of stops outstanding at 60 meters and found a diver with his mouthpiece out that I saw OK only a few minutes before. I have a plan for most things but that one would be hard. 20 minutes and I'd blow it and if we both walked out of the chamber told we could never to dive again it would still be a good day. 40 minutes on helium is both dead territory even without a prior problem.
Sorry. We're miles off topic.
My point is when we are talking about 2kg (and you are wearing a single, so one would hope limited deco) personally I would not be worrying about the 2kg either as a belt or non-ditchable weight. If you can't swim up a 2kg weight you have bigger problems.
Yes, I agree, I may then consider a P weight as an extra 2kg on the back is not going to cause me any problems in lifting it.
However can anyone tell me if you need ditchable weights for any part of the Dive Leader course ?
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