What am I missing here .....?

[Kristen]

My mate had his first open water dives at the weekend at Wraysbury. He's a big bloke (some 6'5'') and a typical UK diver's physique. Anyway, he needed an incredible amount of lead to keep him underwater and even then he kept slowly rising to the surface on some but not all occasions.

Relevant facts are:

single 12 litre cylinder;
semi-dry (not a drysuit);
standard BCD and inflator not leaking air into drysuit;
max 6ish metres depth;
he assures me he wasn't swimming upwards nor was air being caught in his wetsuit etc;
in total the instructor put over 30kgs of lead on him (I think he said it was 34kg) (I double checked he didn't mean lbs)

Now this appears to be a massive amount of lead - he is a fair bit bigger than me but, proportionately, no where near that much bigger to require that much lead.

Could this just be a wetsuit buoyancy issue or am I missing something ? He says that he is not winding me up and that he was on occassion crashing into the lake floor and then slowly rising.

Any ideas to explain this ?

[Gavin Smith]

I doubt if it was 34kg (my wing couldn't even lift that).

Gavin

[Conor]

I'm not an instructor btw but...

Sounds bizarre. It is possible he was swimming upwards but didn't realise it. Did he float up when he stopped swimming?

Alternatively he could have had a small leak in the LP feed to the BC causing air to fill his jacket slowly.

To be honest if he took that much lead (more than half my bodyweight) he probably would have to be about 6'5'' and weigh only 40kg

[Conor]

Are you sure it wasn't 34lbs? about 17kg, which would be quite alot but possible for a large blokes wearing a lot of neoprene

[Kristen]

He's confirmed it was 25kg rather than 34 and that LP wasn't leaking and that he wasn't swimming upwards - v strange.....

Not a big OMS wing then Gavin ???!!!! (I made that point to him re: CD TDB)

[daz]

Well if he sinks OK then I'd guess it is to do with his breathing control and maybe busy fins....

Even if he does not think he is swimming up if he is diving with a feet down attitude (Which is common if he is overweighted) then he could be propelling himself upwards and then any air in the jacket is going to expand etc.....

That does sound like a huge amount of weight.

Daz

[Gavin Smith]

Originally Posted by Kristen

He's confirmed it was 25kg rather than 34 and that LP wasn't leaking and that he wasn't swimming upwards - v strange.....

Wow - that's still an awful lot of lead.

I'd still question whether it's kg or lbs.

That's 6 of the large weights round a belt.

Gavin

[bottle_monkey]

34lbs is a lot but not unheard of. I have a mate that when he started diving needed about that much and he sounds about the same size as your friend (also in semi-dry). I myself use about 28lb in a semi dry and I am a lean 6ft 3 (and yes I have tried with less and I just won't sink)

I would assume it is not 34kg cos that is a stupid amount of lead

[Conor]

...almost a twinset worth of lead

[bottle_monkey]

whoops just re-read the thread

25kg is alot!