The Vertical Wreck

Update 3/03 -The wreck is now lying horizontally on the bottom in a depth of 42 meters

Last Dives on the Vertical wreck

Author: Stephen Burton, Technical Diving Instructor

History of a unique dive site

Easily Pattaya’s most famous dive site, the Vertical wreck has attracted thousands of avid Scuba divers from around the world to experience the wonder of swimming around this unique underwater structure.

Prior to its’ sinking on 25th August 1996 the ship, originally build in Japan and called the ‘Koho Maru 5’ lead a most unremarkable life carrying LPG from one destination to another. It had seen little of Thai waters until later towards the end of its useful life, the ship was purchased by a Thai Company and renamed the “PAK 1”

The ships previous life above water was no indication as to what strange goings on it would be party to as a shipwreck. The ship just didn’t want to behave like a normal shipwreck at all! Ships have sank in their tens of thousand since millennia, but ‘Pak 1’ did not want to lie down. ‘Pak 1’ sunk for the first time in a storm at 11 degrees 41.98 North, 101 degrees 40.86 East. Only 2 of the 11 crew members on board survived. The ships only lifeboat lay on the seabed 60meters (200ft) down next to the wreck as a testament to how fast she sunk. Nothing was ever heard of the missing crewmen who, it was assumed went down with the ship or perished at sea. Neither were any body’s found in the wreckage.

First dives at the Vertical Wreck

News of a first sinking spread quickly through local fishing boats, as wrecks attract a lot of large fish. It wasn’t long before a local skipper informed Stephen Blumenthal, Director of Mermaids Dive Center, and the first exploratory trip was organized to check it out. The first trip revealed what an outstanding wreck it was. Ideally positioned in an Area of outstandingly clear water. The wreck seamed to have everything, and with the shallowest area the bow only 5 meters below the surface, and the ships stern resting at 62 meters. All levels of divers from absolute beginners to the highest qualified TRIMIX divers could have the best dives of their lives there.

The years passed. The wrecks’ reputation continued to grow. Every weekend saw more and more dive boats heading out to her. Mermaid’s Dive Center ran monthly trips to the Vertical Wreck, with divers of all experience levels enjoying this unique attraction. All dreaded the day when rust would finally eat through the tanks, and the gas contained would leak away causing it to sink…Estimates put this at around 25 years in the future. But it was not to be. No one could have imagined that it was the gas that was keeping it down!

Why did it sink Vertical?

In all steel ships that are still afloat, the lack of water in the internal sections below the waterline keeps the vessel afloat. What usually causes a ship to sink, is a hole below the waterline, which allows water to flood down and fill up all the internal compartments. PAK 1’s massive storage tanks had been fully loaded with 600,000 Liters of LPG, and with a density slightly less than sea water, once the ship sank, the liquid LPG kept it
floating vertically upright but not with sufficient buoyancy to float it on the surface. The weight of the massive engine in large flooded stern section kept this portion firmly embedded in soft muddy bottom, with the lighter bow section pointing skyward. PAK 1 leaked small amounts of gas, and diesel oil throughout its life as a vertical wreck, but during the last few months of 2001 the amount of gas leaking from the wreck noticeably increased. In December 2001, a large noisy jet of gas erupted from a corroded pipe fitting on the forward tank, created a large ‘Jacuzzi’
of smelly gas 10sq meters area on the surface. An early sinking seamed imminent, as all the gas that everyone believed was keeping it up was quickly escaping… Then something unheard of in history of ship wrecks occurred; 6 years after it’s sinking, PAK 1 released itself from a fate that faces all shipwrecks… and refloated !

  Dives on the Floating Vertical Wreck

Mermaids Dive Centers February 2002 Vertical Wreck Trip customers were treated to the most unusual spectacle of diving on a drifting, floating, Vertical, shipwreck. Divers who had previously visited the ‘VW’ were in for a special treat. Areas of the wreck that were previously undiveable due to extreme depth, had risen 12 meters(40ft) into shallower water. Recently qualified DSAT Tec Deep students had the unique opportunity to examine sections of the ship that were previously submerged in the mud, swim under the stern for a once in a lifetime view up at the huge bronze prop and massive Keel of the tanker pointing up towards the surface.

The Thai Navy acts. Operation ‘Sink Pak 1’

By this time, PAK 1 had refloated so much that the forward LPG tank was exposed above the waterline. With no lights or other means of identification apart from a weak radar echo from the jagged steel of the bow section above water, the refloated PAK1 drifting in and out the major shipping lanes represented a formidable hazard to other shipping such as cruise liners and oil tankers. Collision with the exposed high pressure LPG tank could have easily ruptured the containment vessel releasing the entire cargo of several hundred tons of LPG. Had this happened and the gas ignited, the magnitude of the resulting explosion would have matched that of a small atomic bomb, easily destroying the colliding vessel, and severely damaging any other shipping within a mile or so radius. On the 6th of March 2002, the Royal Thai Navy acted to prevent further loss of life. 5 Navy vessels were involved in an operation to ‘Sink Pak1’.

An area chosen for the sinking some 100 miles away from where it was floating required a day and half tow by 2 powerful tugs to relocate it. At its designated ‘sinking site’, PAK 1 again decided to play ‘hard to get’ and resisted all attempts to sink it by releasing its remaining cargo in a controlled manner. The final order was given out to use explosives… four blocks of C4 explosive were fitted to the tanks, detonators fitted and the first of attempt to blow it up started. Unfortunately all 4 charges refused to explode! A second attempt with explosives proved slightly more successful detonating one of the two huge cargo tanks, that ruptured successfully with a massive explosion and huge release of gas, though only 1 of the 4 charges exploded successfully. With the whole area reeking of gas, The Navy wisely retreated to a safe distance of 10miles to allow the gas to dissipate safely before returning to send divers down to examine PAK 1.

This was not a good time to light a cigarette. But PAK 1 was not going to sink this easily, and lightened by the exploded tank, it now rose even more above the ocean to a height of nearly 30meters (100ft). Reports of the sinking from this point on are sketchy, but somehow using two nearby tugs and massive force, the ship was eventually laid down on its keel.

First exploration dives onto the new ‘Horizontal Wreck’ First exploration by local divers onto PAK1 in its new position took place just 1 week after the Navy operation to sink it. The wrecks’ new location is at 12 Degrees 5.53degrees North, 101 Degrees 40.95East. The ship lies upright on the bottom in 42meters of water. The wreck is now much closer to the Thai mainland now, being just 30 Miles offshore.

The Bow Section

Descending down the main buoy in clear water reveals nothing until around 25meters depth is reached, where the dark outline of the ship appears. A thermocline exists around 30meters depth, and the visibility drops somewhat to around 5meters as you descend into this region. Checking out the bow area before continuing aft, it’s strange to see the wreck in this new position. Both Gas tanks are now gone, with deep holes going down into onto the bare keel of the boat where they used to be. I wonder what happened to the second tank?

Dropping down into one of the Tank spaces onto the bare keel of the boat is eerie, and extreme care should be taken not to use the fins as you move about, to avoid complete silt out. Vertical ascent out of a silt-cloud of your own making may not be possible if you ascend into over-hanging steel structure or cables. Many cables, ropes, and fishing line cover the wreck.

The Stern Section

Continuing aft from the bows greets the diver with a tremendous site; the bridge and cabin area rises clear and bright out of the thermocline, still in it’s original white coat of paint, and is sure to get the cameras clicking. This is the best area of the wreck, and worthy of spending much time exploring. Easy penetration in good light is possible in the bridge area. More difficult penetration exists in the engine room and crew quarters only for those trained in advanced wreck penetration techniques. Swimming around the stern over the winches and deck gear, reveals a lot of fishing lines and cables still hanging down everywhere to get snagged on – take care.. Continuing on up to and above the bridge back to the surface reveals the ‘crows nest’ rising up high above the ship to around the 20meter mark.

Who can dive the new ‘Horizontal Wreck”

All areas of the wreck are located quite deep, but within the range of recreational divers. Divers with less than a PADI Advanced Certification will not be permitted to dive this wreck. No decompression times on this wreck are quite short breathing air, and the use of NITROX together with the PADI ‘Deep Diver’ course is highly recommended to safely explore the whole site. Even so, with dive times limited by ‘no deco limits’ and tank capacity, by far the best exploration of this site is by using the techniques taught on PADI’s new TecDeep Course. 4 tanks and unlimited decompression will provide for some outstanding dives on this wreck.

Thanks & Acknowledgements

Stephen Blumenthal & the Staff of Mermaids dive Center for technical Assistance and Mixed Gas. ‘The Toy’ Dive Center, MaePim Beach, Thailand. For first dives on the Horizontal Wreck! Commercial Diver Mr. Fred Evans for the ships plans, and excerpts from his own accounts on the ships condition. Dr Pichit Muangnapoe for translations of Thai articles concerning the Vertical Wreck. Gamefish & Boat Magazine Oct-Nov 99 Issue, for a fisherman’s view of the Wreck. Pattaya Mail Magazine 15 March 2002 Issue, for account of the Thai Navy’s ‘Sink Pak 1’ exercise.