A cautionary Tale!!

[Forest Diver]

I have just had a very good weekends diving off Porthousock in Cornwall.

I had recently got myself a set of twin 12s. I did a trim/boyancy check in at the NDC at Chepstow and had a great dive in v/poor vis before going and ran the set down to 40bar before doing the final checks in fresh water.
I shed all my weight apart from the set and was floating at a high forehead level (slightly overweigted but still with ankle weights).
I concluded that and additional 2kg would be OK for salt bearing in mind the air for full tanks weighed in at 6Kg.

Boy how wrong I was, I descended on the Manacles to 30m and had a good look around (superb jewel anenomes - all shades - stunning , massive spider crabs etc) before working up to 12m at the reef top (always a little too bouyant but put that down to trapped air in my suit) , I then felt way too bouyant and despite dumping all my wing and suit and even with the addition of a couple of spare kg from the group ended up making a too bouyant ascent from 11m missing the satfey stop.

Moral - Check weight in salt with new kit before use - the following day I added 6kg and was OK, I felt very embarassed at causing the group unnecessary problems through my lack of planning, one of whom, Tim, helped slow my ascent and missed his own saftey stop in the process.

I know Im a prat but I have learned some vaulable lessons and belive me the feeling that you may have compromised a buddys saftey through stupidity is worse than any other diving experience i can recall.

Its hard to admit your mistakes in public but if it helps someone else its worth it!!!!

[Diving Daisy]

Well said, we have all 'learned' at some point in our dive history, and I am sure we all still learn!

[torbaydiver]

Diving at the same site my buddy missed a 8 min deco stop so I wouldn't worry too much about missing a safety stop !
Nice dive though !
Steve

[Digger]

Well, you shared it, and you learnt from it. There's plenty I know would have tried to blame it on a bit of kit or someone else, or generally not seen the problem. You have, and all credit to you for recognising it and doing something about it. Don't worry abotu your buddy. It was their decision to follow you and slow your ascent. They know the rules, just like you do, and they're ok so no major worries. You might want to talk it over and work out what you'd do if it happened again so you know in advance. Anything from sticking inflators to lost weights could cause it another time, so best to know the plan.

6kg from fresh to salt though? I reckon you should see if you can cut that down to 4. It's not right by my calcs really, and I've never added that much to go from one to the other in identical rigs.

[bang-on]

forest diver,
i think you will find everyone on this forum has had an incident (f**k up) at some point and many a tale to tell over a beer or two,those who dont just have bloody bad memories!!
that said the secret seems to be to learn from any mistakes and equally as important from other peoples,i doubt there's much that can be screwed up that hasn't already been done,done,done.
i congratulate you on your healthy attitude to incidents and i suspect this will stand you in the future.

cheers
barrie

[Mark Chase]

I suffered similar embarrassment when putting a 200g thinsulate under my Neo dry suit for the first time. Unfortunately I was diving with Bob Cooper so the embarrassment was compounded. I held deco at 6 but my usual steady 5min ascent to the surface was more cork like My error was based not on lack of experience as such but more on overconfidence that I could cut the corner and deal with it. Doh wrong

Moral of the tail is, all essential equipment should be properly tested before you dive it in anger and if its not essential equipment why are you carrying it?


ATB

Mark Chase

[bubs]

Dont worry I also had a similar incident- after changing to a very thick undersuit and using an ally tank- the last part of the dive was difficult to say the least spent most of it in the head down position finning down to keep me down- this meant it was really difficult to dump ar from drysuit. Eventually it all got too much and made a very embarassing 2-legged salute upwards in front of a very experienced diver- who thought i was experienced too- doh!

[Padowan]

You can actually work out exactly how much weight you need to add between fresh and salt water. If you are perfectly weighted with empty tanks in fresh water, you then need to stand on your bathroom scales (or perhaps a weighbridge if your scales are like mine and don't go up that high!) and make a note of the total weight of you and all your kit, weights included.

You know that seawater is 1.03x (3% more) dense as fresh water so you need to work out 3% of the weight of you and all your kit - to give you an idea of how much this ACTUALLY works out to be, if you and your kit weigh 140kg (quite possible with twin 12's, backplate, torch etc) 3% of 140kg is 4.2kg.

I've used this method, and unsurprisingly, (because physics is physics) it works very well.

Caveat for the pedants: this assumes that the +ve bouyancy you recieve from the displacement of the additional (in this case 4.2kg) lead is negligible, which it is.

[Helen F H]

I found out that 14kg with a single 10 is nowhere near enough lead to keep my fat arse underwater.

[HelenM]

I had a similar problem on my first sea dive with my 12s. Added a couple of kilos to the fresh water weight (which had worked perfectly). Unfortunately on the way up had that horrible feeling of 'oh b*ll*cks'. I managed to hold my stop - just - but the only way I could do so was by adopting the 'dead fly' position on my back beneath my reel. It all caused much amusement for Mr Tierney who invented a whole new set of underwater signals for 'what the f*** are you doing?'. He kept demoing how I ought to be hanging. Unfortunately I couldn't gesture back 'I know that you moron' without risking heading skywards.... any deviation from the dead fly and I started to move up*. 'Twas a very amusing conversation back on the surface!


* I have no idea why this position worked better - any one else any thoughts?