Tuesday 23 September 2008

EN 144-3

EN 144-3:2003 is now the new standard for "Outlet Connections For Diving Gases Nitrox And Oxygen", though until August 2008 valves may have been supplied either to this or the previous national standard. The standard now applies to the connection between a gas cylinder-valve and a first stage or compressor connection when the tank contains gas with an oxygen content greater than 22%. What it means is that your nitrox cylinder will have a dedicated outlet valve, your nitrox regulator will have a dedicated connection to your cylinder valve, and filling stations will have a dedicated nitrox filling connector.

Brussels decided that some new regulations were needed regarding the transport of gases under pressure. They decided that each gas should have its own individual tank valve fitting, so that the wrong gas could never be put into a particular cylinder.
There was already a DIN fitting for use with air cylinders (DIN being the German standards body), so they decided to stipulate an entirely different fitting for use with air mixes with a higher content of oxygen than normal - nitrox. They came up with the M26 valve thread, with a larger diameter than the now familiar DIN fitting.

The recommendation was not mandatory till August 2008, and a poll of Greek service providers indicated that no-one seemed aware of it.

As instructors and service providers we have a duty of care to our students and clients. Failing in our duty exposes us to both legal action and liability for any harm caused. Our 3rd party liability insurance may, or may not, decline to pay out, partly or fully, in an accident if the breach of duty of care is bad enough.

Thursday 18 September 2008

I've given up using Chemical Lights on night dives

For the following reasons:

- Single use
- Limited life
- Can be accidentally activated
- Need to be properly disposed of following a night dive

Now replaced with 'YO ZURI' Japanese fishing LED lights that:

- Are reusable
- Only activate upon contact with water
- Offer 1000 (one thousand) operating hours
- Stop flashing once contacts dry
- Offer a (brighter) flashing light in a choice of Blue, Green & Red colours

These LED's can be purchased from most retailers selling fishing tackle. I suggest you opt for the larger three and a half inch long LED offering one thousand operating hours, rather than its smaller (seven hundred operating hours) counterpart.

Saturday 13 September 2008

On tying knots

In a 'Search & Recovery' class we teach the art of knot tying. For those of you who may experience difficulty mastering the Bowline & Sheet Bend, here are two videos I found on YouTube that clearly and simply demonstrate tying these knots.


Sheet Bend

Wednesday 3 September 2008

Dive site mapping

The role of a dive leader demands knowledge of dive sites as well as the use of dive site maps when conducting a pre-dive briefing. This knowledge should include layout, distances, depths, entry and exit points as well as any possible currents and hazards. Safety is an important factor but having a map will allow divers to visit the best features of the site by marking where they are and what to look out for.

One of the easiest ways to map a dive site is to use a large slate, tape measure, compass, depth gauge and fixed buoy in order to create an accurate picture of the underwater terrain.

Large slate: If possible use one with pre-printed grid markings.

Tape measure: purchase a 30m reel from your local hardware store.

Compass: use a compass to draw intersecting distance arcs.

Secure buoy: use as a central point from which everything is to be measured.

Using this technique

(1) Start by drawing a quick sketch of the site from memory on a slate - it's a good base from which to add measurements and bearings and will help you set parameters.

(2) Select a central point from which everything on the site will be measured (setting up a buoy will allow you to attach a reel to measure distance)

(3) From the central point swim using a U search pattern as it a good way of covering a large area.

(4) Use kick cycles to measure distances between each feature. Find out how many kick cycles it takes you to fin from one end of a 10 meter line to the other. Use this number to convert kick cycles to meters when moving from one feature to the next, noting distance and depth.

(5) Take a bearing from each feature, again from the central point. Mark these on the rough sketch.

(6) Note features as not-to-be missed areas of the dive as well as of any potential hazards. Note entry points for both boat and shore diving.

(7) If drawing to scale you'll need grid paper, protractors and rulers. This will highlight areas that may need to be surveyed if they don't match up correctly.

(8) Note the depths to the bottom if known (make a note after every 5 meters or so) - this helps create contour lines on your final version.

(9) Add relevant topside features (car park, evacuation area, as well as where oxygen and first aid kit is positioned).

Tuesday 2 September 2008

Cylinder cleaning

A recent query from a colleague regarding cylinder cleaning prompted me to list this article on 'Cylinder cleaning and tumbling' by Dr.Dick Boyd, Greg Kent and Dave Anderson of Global Mfg.Corp.

Click on the title to peruse article.

Diving Tourism

Out of the approximately 3,2 million active European divers, an estimated 825,000 tend to travel to their diving destination whilst on holiday each year.
During an average ten day stay, the divers expenditure from dive travel can usually mount up to approximately 3,800 million Euros.

Source:World Recreational Scuba Training Council