Diving the Derna, or was it the Hartburn and a very bent computer...

[onthetrain]

I expect you lot get fed up hearing from me about midweek trips but here goes anyway....

Last evening was a particularly beautiful one in Poole. The sun was shining, there was barely a breeze and the surface of the sea was like glass. Amidst this vision of virtual hell our merry band of 11 set off from Poole quay for an evening dive on the Derna which lies well out in Swanage bay. A run of about 20 Miles from Poole.

We left the quay at 1800 & were expecting slack water at around 2030 so it was a leisurely run out giving plenty of time to swap stories, drink tea and set up your kit several times

We arrived on site at about 2000, shotted the wreck right by the propellers and at just after 20.30 in we went. I was running a little experiment on my computer but more about that later.

As we dropped down the shot it was pretty dark and there was a fair bit of plankton in the water. I feared the worst as we descended but at around 30M the vis cleared and we saw the wreck spread out some 14 or 15 M below us.

The shot was perfectly placed just forward of the very impressive and intact prop. The wreck is well broken and is sunk into the gravel seabed on a number of places. However, swimming forward from the prop you soon find some really impressive boilers, just forward of the boilers there is access to the engine room but as we were at around 43M and I didn't have any helium in the mix I did the sensible thing and stayed outside

Swimming towards the bows there are lots of interesting things to see, ladders, large batteries etc litter the seabed. I expect that there may be shinies to find, but frankly I was enjoying the swim and the wildlife too much to spend too much time hunting.

We started our ascent after 30 mins bottom time......Total run time 67 mins.

That leads me to my experiment

I use a Suunto Vyper computer, but it is very conservative and doesn't allow for Pyle stops or accelarated deco mixes as it's single gas. Normally I do my deeper dives on tables with the Suunto in guage mode. My experiment was to compare the Suunto with a VR3 set to a 27% back gas with an 80% deco mix. Guess what, the Suunto didnt like it much

After 28 Mins bottom time it was showing 37 mins of stops. After Pyle stops at 27M 19 & 12 this increased to around 42 mins. After switching to the deco mix (80%) at 9M and doing 5 @ 9 & 15 @ 6, we were clear on the VR3 but we hung around for an additional 11mins @ 6 - 3M to clear my buddies citizen aqualand. After all this the Suunto was still showing almost 20 mins of stops.....

Guess I'll be locked out for 48 hours

Anyone want to sell me their VR3????

Final note, Though the skipper assured us the wreck we dived was the Derna I have my doubts, The Derna is suppossed to sit upright with the bow & stern fairly intact. Either it has taken a real battering recently ot this was the hartburn which lies nearby... Either way a great mid range dive if your looking for something a little different out of Poole, Swanage or even Weymouth. Certainly a superb way to spend a Monday evening. Mind you we didn't get back to Poole until about 11.40PM and by the time I got home it was like 12.30......SWMBO was pleased

Alan

[Janos]

Nice report mate.

Who did you go out with?

Janos

[onthetrain]

Originally Posted by Janos

Nice report mate.

Who did you go out with?

Janos

Trevor Small who runs a Bullet 38. He can be contacted on 07802231196