Archive for ‘Training’

Unicorn Wreck diving with DJL Tech crew

By , 22 April, 2016, No Comment

Unicorn Wreck diving with DJL Tech crewDavy Jones Locker instructor Matt is also a certified tech diver and has written a new article for the DJL Blog. The tech crew visited the Unicorn Wreck near Koh Tao for some experience diving and also to complete the training of students taking tech courses



Unicorn Wreck diving with DJL Tech crew“The DJL Tech crew have been diving the Unicorn Wreck which is located around 4 nautical miles North of Koh Tao in around 48m of water. Preparation for the the dives began the day before with the checking of equipment, mixing and analysing gasses, and dive planning. It was then a nice early start to move the equipment down to the beach, on to the longtail, which would then take the team to the bigger tech boat.

Once the mark had been found and the shot line released it was time to kit up, do the all important checks, and get into the water. The team was split into two groups which consisted of; Manuel and his 2 students as one group; Tim, Ed and Matthew as the other. Tim, Ed and Matt were in the water first to go and tie off the shot line securely to the wreck so the tech boat could provide cover on the surface. Our team was eager to get in to the the beautiful clear blue waters and descend. The perfect conditions meant that we were anticipating a fantastic dive.

Unicorn Wreck diving with DJL Tech crew

Unicorn Wreck diving with DJL Tech crew







Upon reaching 30m, the team could clearly see the structure of the wreck reaching up from the depths below. The shot line had landed just off the wrecks port side, which allowed Tim to tie into the wreck on the mast with ease. The rest of the dive was used to explore the bow section of the wreck and to make a quick visit to the bridge. Many large schools of fish call the Unicorn their home, which provides another degree of entertainment while navigating along the wreck. The wreck is also home to an abundance of soft corals which have attached themselves to the hull of the ship and have flourished.

Unicorn Wreck diving with DJL Tech crew

The rest of the dive was spent ascending up to the surface and completing all decompression obligations. Everyone had enjoyed the dive, especially due to the great visibility. There is more information about the Tech courses we offer on our techdivethailand website. If you would like to dive with us, or enroll onto a course to become qualified to see these amazing rarely dived wrecks please send an email to or click on the contact us button above and our staff will be happy to provide more details.”



Wreck Spec advice

By , 10 April, 2016, No Comment

wreck spec adviceDavy Jones Locker instructor Dani recently took one of our Divemaster candidates Kieran through his Wreck spec,  following that she has written a new article for the DJL Blog containing some great wreck spec advice. Wreck exploration and penetration is one of the most exciting aspects of diving but does have some inherent risks and dangers that divers need to be aware of.


“Danis Wreck spec tips :

For many divers the greatest thrill is exploring ship wrecks. But, as you progressed through your open water training, you were no doubt constantly reminded about the dangers of entering wreckage or any overhead environment. The dangers are real and valid whether you are a relative new comer to diving or a seasoned dive professional with many thousands of dives.

Cave or wreck?

• The differences between cave and wreck are many. Caves have generally one exit and this makes them seem dangerous. Wrecks, however, appear to have many, and this leads to diver complacency and failure to obtain training. The cave typically has an out flowing current to help your exit, whereas the wreck offers no assistance or consistency and actively seeks to entrap you with its rusted metal claws.

Why should I get my Wreck spec?

• Before you enter any wreck you should obtain Wreck diver training which will help you start appreciating the added hazards that go hand in hand with your trips into the magnetic overhead environment. On completion of training, you will be able to cast off your “open water safety wheels” and enter the most hazardous of the underwater domains…the rusty shipwreck. There are many reasons to go inside a wreck. Many of you will, no doubt, have prematurely been attracted to the darkness and ventured where you shouldn’t. It is very alluring to stick your head in and before you know it your whole body is propelling you into a possible early grave. However, after as little as 3 days training you can safely penetrate these passages and live to tell the tale.

• Wreck Penetration by definition means going into an area where direct access to the surface is not available. Even a brief “look see” means you have penetrated the wreck and should have laid a line to show your exit route. Wreck penetration should always involve line laying, and good line technique is an art in itself. Wreck penetration techniques are beyond the limits taught in a standard Advanced open water course.

wreck spec advice

Standard wreck courses, often called a speciality course, offer an insight into wreck history, focus on basic mapping, kicking techniques, and line laying. These speciality courses are aimed at the diver who seeks more interesting dive destinations without the hazards and dangers of entering the overhead environment. Typically, a linear distance to the surface limit is imposed of 40m, which means that a wreck laying in 25m allows a maximum penetration of 15m. An Advanced wreck course generally has a maximum depth limit of 50m while breathing air, but it would be advisable to use trimix inside wrecks deeper than 30m.

There are no restrictions on penetration other than adhering to the following safety protocols:

1: No entering areas that two divers cannot enter side by side

2: 1/3 rd’s gas management protocols adhered to

3: No equipment to be removed within the overhead environment

4: Guidelines to be used, in all overhead environments.

When entering a wreck the guideline will be attached in two places called the primary and secondary tie offs and you should always lay a new line if you suspect an old one. ollowing a permanent guideline.

Propulsion techniques

• A good propulsion technique will ensure you have relatively clear water to exit in. Many experienced wreckers simply use a pull and glide technique as this tends to preserve the visibility. There are some awkward skills to master, what with laying the guideline sensibly and holding your dive light all while navigating the wreck and avoiding silt outs.
• We will practice Flutter kicks and modified frog kick during dive 3
If the size of the corridors inside allows, divers may wish to use a frog kick or modified flutter kick. These types of kicks direct the power of the fin kick backwards and not up or down which will help maintain visibility. With the fin power directed behind, you should obviously have perfect buoyancy control or you will find yourself constantly falling to the floor

Hazards of silt outs

• Silt is a potential killer while wreck diving and no matter what your fin style, Silt will rear its ugly head at every chance. Silt is defined as particles occurring in the water, and due to their suspension, affecting visibility during the course of the dive. Silt can be either manmade or natural, i.e. rust particles or clay particles. There are various types of silt you may encounter in a wreck, these include:

1. Sand grains: the least serious, generally falling out of suspension very quickly.
2. Mud: A bit more serious, because it is easy to disturb and may take a long time to settle.
3. Clay: More serious, easy to disturb, takes hours to settle, sticks to anything
4. Volcanic ash: While not exactly common, proves a serious problem due to magnitude of deposit and fineness of particulate. Some popular sites in the Philippines suffer very badly, with ash deposits almost a metre deep in places
5. Man Made: Due to the many types of substances used in ship construction, the following are included: Rust particles, carpet fibres, hardboard, and wooden panels, expanded foam panels. Oil /fuel residues, becoming re-suspended, Coal dust etc

wreck spec advice

Wrecks lay in all manner of positions on the seabed; it would be very difficult to say where most silting would occur. With floors becoming ceilings and sidewalls becoming floors, its best just to watch where you are going, and use the most suitable propulsion techniques. In areas of suspected silt build up, it would be prudent to maintain a closer position to guideline, often maintaining a “loose ok” sign where visibility is compromised. A good approach to entering a silty overhead environment is to touch nothing and watch where you are going!

Keep your group small

Wreck exploration is better accomplished with a dive buddy, but not a dive party! The buddy behind can illuminate possible line placements and help with any wreck entanglement problems. The bigger the group that enters the wreck the poorer the visibility and this will have a dramatic effect on group safety.


Equipment should be stream lined with no danglies. Spare masks or back up knives or tools should be kept in pockets, (but back up lights are never put in pockets). A rusty wreck tentacle will actively attract the ill prepared wreck diver, and often, sadly leads to an indefinite bottom time!

Communication Methods

Wreck spec advice1. Tactile signals can play a big part inside a wreck. You may have the brightest, most expensive dive light there is, and two back ups, but if the visibility is nil then they won’t help you… A touch contact system has been devised that allows a team of two or more to exit safely and quickly. Devised by Don Rimbach (well known Cave Diver), as a means for several divers to exit an overhead environment. This method uses squeeze signals. Lead diver waits on guideline for diver behind to make contact (above knee preferably). Second diver PUSHES ONCE to GO. To stop exit Second diver SQUEEZES ONCE (lead diver waits). To back up second diver PULLS BACK on lead divers leg.

2. Finally, imagine you and your buddy, in zero visibility, are following a line and you encounter a “dead end” and need to turn around. Discuss with your buddy a suitable touch signal you could use to achieve this

3. The hand signals below show some new signals peculiar to the overhead environment. These signals are very similar to those used in Cavern and Cave diving. The signals for “OK”, “HOLD”, “EXIT” are control signals. They are to be mirrored back to originator to make sure that they are understood.

wreck spec advice

wreck speck advice









Ending the dive for ANY reason

When in any overhead environment, any diver can call the dive at anytime for any reason. Never succumb to peer pressure and enter the wreck if you don’t feel “up to it”. All divers have differing performance levels that vary from day to day.
As you swim through the wreck, accept that the dive maybe finished by any of the team for reasons that may not be obvious.”



CCR Cave Diving Song Hong

By , 30 March, 2016, No Comment

CCR Cave Diving Song HongBeing an open circuit cave diver and enjoying the challenge of the deep caves of Thailand I have for a long time wondered about the benefits of closed circuit rebreather technology in relation to caves. As CCR divers will tell you the units work best in a classic diving profile (max depth work shallower) and when a diving colleague Bruce Konefe took me on a course, ANDI CCR cave, I was intrigued to learn about the gas management rules for cave profiles as caves tend to follow their own profile without regard for the divers.

The cave where we were to complete our training, Song Hong, is a huge sink hole slap bang in the middle of Thailand. Song Hong is well known with local cave divers and stands out for its’ enormous size and depth with exceptionally clear water below the hydrogen sulphide layer. Part of the sink hole which allows for direct access to the surface is used by technical divers wishing to complete wishing to complete deep trimix diver training, avoiding the problems associated with currents and elevating respiration in the sea.

ccr cave diving song hongAs any rebreather diver will tell you you, rebreathers, due to the design do not lend themselves to achieving good trim, a skill that is essential for cave diving. A lot of time was spent moving weights and adjusting the height of the wing to counter the lift at the shoulders caused by the counter lung. The rebreathers I had with me, Evolution and Inspiration, due to the box they are protected by make it hard to move weights and tanks, to assist in this and I found it easier to remove the can and head and put them in a customized box. This has helped a lot and now it isn’t so much effort to maintain a horizontal position acceptable for cave diving.

CCR diving song hongThankfully the gas management rules were a lot easier to master although I was surprised to see many applications of this. It depends on the amount of divers in a team and the amount of confidence in the individual team members, running from the bare minimum, carried around team members with a variation calculated at the largest RMV of this with a third reserve on top again. This is shared around the team to the old third in third out thirds developed by Sheck Exley with each team member carrying their own reserve. It can be quite unsettling when at depth and on the way in to a cave if you start to have doubts about your buddy’s ability to keep his shit together when the said shit hits the fan and you’re relying on your buddy to carry part of the emergency gas you need to get to the surface! At this point you begin to choose your buddies more carefully bearing in mind it’s the team gas rule that that has helped cave divers push back the curtain and explore deeper and longer cave systems.

CCR cave diving song hongOverall though CCRs greatly enhance the divers ability to explore caves and with careful adherence to the gas rules (whichever one you adopt) and choosing your your buddies with as much attention to detail there is no doubt CCRs take cave diving to another level. Happily, I had good diving buddies and the shared enjoyment of achieving a goal of completing the 60 metre circuit added to the pleasure.

Song Hong CCR Cave diving 2016 from bike09 on Vimeo.


Air Consumption and Ways to Improve it.

By , 18 March, 2016, No Comment

Air consumption and ways to improve itInstructor Dani has written a new article for the DJL Blog offering some great tips on how make your air last longer when diving. It’s not only about what you do while you are in the water, other factors such as lifestyle and preparation before a dive are also important in helping you breathe underwater efficiently.


“Are you constantly finding you are turning your dives based on your air supply? fastest air consumption compared to your buddy’s on the boat? wanting to spend those extra few minutes with that turtle?

You may never have the best air consumption on the boat but you can have the most improved. Here are 10 helpful tips to help you to improve our air consumption and give you longer dives safely…


CCR, Rebreather – Rise of the Machine

By , 5 March, 2016, No Comment

CCR, Rebreather - Rise of the MachineSince the introduction of closed circuit rebreathers to mainstream diving in the early 90’s, the rebreather doesn’t appear to have lived up to the hype. There are a number reasons for this, the equipment is expensive and so is the training when you consider the diving hours required to become proficient on these units, there have also been issues with the reliability of cells and complex electronics when mixed with water. These are factors which have made the inevitable rise of the machine slower but you can’t stop progression and eventually more and more diving schools and facilities will offer CCR training as standard.

At Davy Jones Locker we are rebreather friendly with 2 and 3 litre tanks available for rent, booster pumps for pushing up the o2 pressures needed for deeper dives and extensive training with ANDI, IANTD and in the future PADI/DSAT certification provided for the inspiration classic/evolution vision electronics.

The main reasons for choosing these units to concentrate our training on are the cost, availability and excellent support from AP Valves. The inspiration/evolution units are the most popular units on the market and have more dives completed on them than any other unit. They are constantly evolving and have many unique trademarked features, the cost is also very competitive with a very healthy second hand market with some inspiration classic units changing hands for as little as £600.

CCR, Rebreather - Rise of the MachineWe’re not claiming that these units are the Ferraris of rebreather systems like the JJ or Megalodon which come with a hefty price tag of £7000, meaning a student wishing to train on one of these would have to find around £8000 just to be able to practice after completing the course. The Inspiration/Evolution unit sits comfortably in the VW Beetle category, reliable, low cost with a healthy second hand market enabling a student after paying around £1000 for their course can continue diving for as little as £600 for their own unit.

These units are rated to 100 m and with some modifications can increase this to 150 m so there is plenty of scope for experiencing dive exploration and becoming part of the rise of the machine.

Check out our video below to see the evolution in use.


HMS Repulse wreck, South China sea.