Herakles (pusher)
Encyclopedia
| Converted: | 1991 |
| Classification: | DNV Det Norske Veritas Stiftelsen Det Norske Veritas is a classification society organized as a foundation, with the objective of "Safeguarding life, property, and the environment". The organization's history goes back to 1864, when the foundation was established in Norway to inspect and evaluate the technical condition... +1A1 R280 Pusher/Tug ECO ICE 1B |
| Main engines: | 2 × Caterpillar Caterpillar Inc. Caterpillar Inc. , also known as "CAT", designs, manufactures, markets and sells machinery and engines and sells financial products and insurance to customers via a worldwide dealer network. Caterpillar is the world's largest manufacturer of construction and mining equipment, diesel and natural gas... 3606 DITA (2 × 2,030 kW) |
| Auxiliary engines: | 2 × Caterpillar 3306 DIT (2 × 161 kW) 1 × Caterpillar 3512 DITA (807 kW) |
Herakles was a pusher vessel
Towboat
Not to be confused with the historic boat type with the same name, also called horse-drawn boat.A towboat is a boat designed for pushing barges or car floats. Towboats are characterized by a square bow with steel knees for pushing and powerful engines...
owned by Finnish
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
towing and marine salvage
Marine salvage
Marine salvage is the process of rescuing a ship, its cargo, or other property from peril. Salvage encompasses rescue towing, refloating a sunken or grounded vessel, or patching or repairing a ship...
company Alfons Håkans Oy Ab. The ship, originally built as salvage tug
Salvage tug
A salvage tug is a specialized type of tugboat which is used to rescue or marine salvage ships which are in distress or in danger of sinking, or which have already sunk or run aground....
Into in 1967, was converted to a pusher in 1991 to be chartered to Rautaruukki Oyj
Rautaruukki
Rautaruukki Corporation is a Finnish company, headquartered in Helsinki, which manufactures and supplies metal-based components and systems to the construction and engineering industries....
and later ESL Shipping Ltd as the third pusher vessel for Finnpusku
Finnpusku
Finnpusku is an integrated tug and barge system owned and operated by ESL Shipping, a Finnish shipping company that specializes in bulk cargo transports in the Baltic Sea. The system was developed in the 1980s by Finnlines, another Finnish shipping company that also managed the vessels until 2003,...
, a Finnish integrated tug and barge system. On 2 March 2004, while heading north with barge Bulk fully laden with coal, Herakles ran into trouble in the Bothnian Sea
Bothnian Sea
The Bothnian Sea links the Bothnian Bay with the Baltic proper. Kvarken is situated between the two. Together, the Bothnian Sea and Bay make up a larger geographical entity, the Gulf of Bothnia...
when both of her main engines began to fail in heavy weather. After the crew was evacuated the combination drifted to the shallows near Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
Grundkallen
Grundkallen
Grundkallen is a Swedish lighthouse on a shallow of the same name in the southern part of the Gulf of Bothnia, some northeast of Öregrund. The current lighthouse was built in 1961 to replace a lightship in the same location...
lighthouse and was completely destroyed.
Career
The vessel began her life as salvage tug Into and was delivered to the Finnish oil and petroleum products companyPetroleum industry
The petroleum industry includes the global processes of exploration, extraction, refining, transporting , and marketing petroleum products. The largest volume products of the industry are fuel oil and gasoline...
Neste Oy by Oy Laivateollisuus Ab in October 1967.
In 1982 she was purchased by Oy Hangon Hinaus Ab, a marine salvage company recently acquired by Effoa
Effoa
Finland Steamship Company was a Finnish shipping company founded in 1883 by Captain Lars Krogius. In Finnish and Swedish The company was usually referred to simply as FÅA. In 1976, the company changed its name to Effoa, a phonetic spelling of the abbreviation FÅA.The company was a founding member...
. In the same year the ownership of the company was transferred to Neptun, another Finnish marine salvage company in which Effoa had been a major shareholder since 1917. The two companies merged in the following year, after which Neptun changed its name to Oy Hangon Hinaus Ab. When Effoa gave up salvage business in 1988 and sold Oy Hangon Hinaus Ab to Alfons Håkans Oy Ab, Into was renamed Herakles.
As part of a restructuring of the company Alfons Håkans converted two tugboats to become pushers and established a charter contract with Rautaruukki Oyj. In 1991 Herakles was refitted with a new bridge and coupling devices by Oy Laivateollisuus Ab in Turku, the same shipyard where she was originally built, and became the third pusher for the Finnish integrated tug barge system Finnpusku that is used to transport raw materials to the steel mill
Steel mill
A steel mill or steelworks is an industrial plant for the manufacture of steel.Steel is an alloy of iron and carbon. It is produced in a two-stage process. First, iron ore is reduced or smelted with coke and limestone in a blast furnace, producing molten iron which is either cast into pig iron or...
s of Rautaruukki Oyj.
When the pushers and barges of the Finnpusku system were sold to ESL Shipping Ltd in 2003, Herakles continued her charter as part of the transport system until her demise in 2004.
Sinking
Herakles sank along with the barge Bulk on 3 March 2004 at around 00:30 (UTC+02) in the Bothnian Sea. The combination, referred to as Herakles-Bulk, had left OxelösundOxelösund
Oxelösund is a locality and the seat of Oxelösund Municipality in Södermanland County, Sweden with 10,843 inhabitants in 2005.- History :The harbour at Oxelösund has been used for at least 500 years. In the 19th century, an increased extraction from the Mining district of Central Sweden , made...
, Sweden, two days earlier and was heading north with the barge fully laden with coal. On 2 March she ran into a storm and the captain
Captain (nautical)
A sea captain is a licensed mariner in ultimate command of the vessel. The captain is responsible for its safe and efficient operation, including cargo operations, navigation, crew management and ensuring that the vessel complies with local and international laws, as well as company and flag...
, not certain if the vessel could safely be turned around in such a sea state to seek shelter closer to the coast, decided to evacuate half of the crew by helicopter. When the port engine began overheating and later the starboard engine lost all power, Herakles-Bulk was no longer able to keep the bow into the wind and began to drift uncontrollably in the storm. The remaining crew was soon evacuated and shortly afterwards the combination foundered in the shallows near Grundkallen lighthouse.
While no lives were lost, both vessels became total losses and the fuel oil from the ruptured fuel tanks polluted Finnish and Swedish coastlines.
The sinking of Herakles-Bulk was the second major accident involving the vessels of the Finnpusku system. In 1990 pusher Finn
Steel (pusher)
Steel is a Finnish pusher vessel owned and operated by ESL Shipping. It is part of the Finnpusku integrated tug and barge system developed in the 1980s by Finnlines, a Finnish shipping company that also managed the vessel until 2003, in co-operation with Rautaruukki for the transportation needs of...
capsized with barge Baltic outside Hanko, Finland, with a loss of eight lives after her cargo of ore concentrate
Ore concentrate
Ore concentrate, dressed ore or simply concentrate is the product generally produced by metal ore mines. The raw ore is usually ground finely in various comminution operations and gangue is removed, thus concentrating the metal component. The concentrate is then transported to smelters where it is...
shifted in heavy weather. In the past Herakles had been involved in several dangerous situations in heavy weather, including one in January 2002 in which four crew members were evacuated by an Estonian
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
helicopter before the captain attempted to turn the combination to the wind near the Estonian coast.
Timeline of events
On 1 March 2004 Herakles-Bulk left Oxelösund where she had stopped while en route from PolandPoland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
to Kvarken
Kvarken
Kvarken is the narrow region in the Gulf of Bothnia separating the Bothnian Bay from the Bothnian Sea...
with a cargo of 13,259.9 metric tons of coal. The combination was heading north towards the edge of ice where she was supposed to rendezvous with pusher Rautaruukki
Rautaruukki (pusher)
Rautaruukki is a Finnish pusher vessel owned and operated by ESL Shipping. It is part of the Finnpusku integrated tug and barge system developed in the 1980s by Finnlines, a Finnish shipping company that also managed the vessel until 2003, in co-operation with Rautaruukki for the transportation...
coming from Luleå
Luleå
- Transportation :Local buses are run by .A passenger train service is available from Luleå Centralstation on Sweden's national SJ railway service northbound to Narvik on the Norwegian coast, or southbound to Stockholm. See Rail transport in Sweden....
, Sweden, switch to an empty barge and head back south.
According to the weather forecast received two days earlier the strongest winds the ship would face would be 13 m/s (29.1 mph; 23.9 kn), but after leaving Oxelösund another forecast was received, this time with maximum wind speed between 15 m/s (33.6 mph; 27.6 kn). Later the chief officer
Chief officer
A chief officer can refer to any of various leaders:In the military, it can refer to certain non-commissioned members:*Chief Petty Officer*Chief Warrant OfficerMarine occupation:*Chief Mate...
noted to the captain that before the ship had sought shelter after receiving weather forecasts of this kind. Several sheltered locations had been marked to the nautical charts by the second officer
Second Officer
Second Officer may refer to:*Second Officer , a civilian aviation rank*Second Officer , a merchant marine rank*A naval rank in the Women's Royal Naval Service*A billet in the Star Trek universe...
, the closest being near Eckerö
Eckerö
Eckerö is a municipality of Åland, an autonomous territory under Finnish sovereignty. The municipality has a population of and covers an area of ofwhich is water. The population density is....
in Åland. The captain decided to keep heading north, but after passing Grundkallen lighthouse the ship would head closer to the sheltered waters of the Swedish coast.
Herakles-Bulk passed the Swedish lighthouse Svenska Björn at 04:00 the following night, encountering only a fresh westerly breeze in which the combination could maintain a speed of 8.2 knots (4.5 m/s). In the following morning the wind turned north and began to pick up, reducing the speed of the ship. After passing Märketskallen at 10:05 water began to enter the cargo hold over the forecastle and, as the waves gradually grew higher, the speed of the combination continued to drop until it was less than 2 knots (1.1 m/s) at 13:00.
At 15:00 steering was switched to manual mode since the autopilot could no longer be used and full engine power was required to maintain heading in such conditions. Herakles-Bulk was pushing the headwinds of 28 m/s (62.6 mph; 51.4 kn) according to its own anemometer
Anemometer
An anemometer is a device for measuring wind speed, and is a common weather station instrument. The term is derived from the Greek word anemos, meaning wind, and is used to describe any airspeed measurement instrument used in meteorology or aerodynamics...
while barely maintaining a speed of 1 knot (0.5444 m/s). The electrical cables and fuel pipes connecting the pusher to the barge were unplugged to prevent them from being damaged or damaging the ship as the pusher pitched violently within the notch. At 15:30 the operational management of the shipping company inquired about the situation and it was decided that company would contact the maritime rescue co-ordination centre (MRCC) which, in turn, would later contact the ship. When MRCC Turku contacted Herakles-Bulk at 15:51 the captain said that he was not sure if the bow could be kept facing the wind. He decided to send half of the crew off the ship because if the combination turned broadside to the wind, there would be a danger of the vessel capsizing.
At 19:00 overheating alarm was received from the cooling water system of the port main engine and its power had to be reduced to half. At times the engine had to be run at full power for short periods of time to keep the bow facing the wind. Shortly after 22:00 the speed of the starboard main engine suddenly dropped from 1000 rpm to roughly 270 rpm, but was restored when the engine was declutched from the shaft. When the second engineer closed the clutch at normal coupling speed of 400 rpm, the engine stalled
Stall (engine)
A stall is the slowing or stopping of a process, and in the case of an engine, refers to a sudden stopping of the engine turning, usually brought about accidentally....
. After restarting he attempted coupling the engine again at 1000 rpm, but it still would not run faster than 270 rpm when connected to the shaft. When the captain received a report that the starboard main engine was no longer usable he decided to abandon the ship and ordered the evacuation of the remaining crew at 22:16. The combination turned parallel to the waves with port side facing the wind and began to drift uncontrollably.
After the rest of the crew had been evacuated Herakles-Bulk drifted to the shallows and sank near the Grundkallen lighthouse on 3 March 2004 at about 00:30.
Evacuation
When the captain made the decision to evacuate the chief engineerChief Engineer
In marine transportation, the chief engineer is a licensed mariner in charge of the engineering department on a merchant vessel. "Chief engineer" is the official title of someone qualified to oversee the entire engine department; the qualification is colloquially called a "chief's...
, who was suffering from gastroenteritis
Gastroenteritis
Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...
, the chief steward
Chief Steward
A chief steward is the senior unlicensed crew member working in the Steward's Department of a ship. Since there is no purser on most ships in the United States Merchant Marine, the steward is the senior person in the department, whence its name...
and two members of the deck crew, MRCC Turku gave the evacuation mission to Finnish Border Guard
Finnish Border Guard
The Finnish Border guard is the national security agency responsible for enforcing the security of Finland's borders...
Eurocopter AS332 Super Puma OH-HVF which was returning from previous mission and still had more than two hours of remaining flight time. MRCC Göteborg authorized the Finnish helicopter to enter Swedish airspace as the combination was six miles into territorial waters of Sweden. The helicopter arrived and began lifting the crew members from the rear part of the cargo hold at around 16:50, a task that was very difficult due to pitching and rolling of the combination. The crew was brought to Mariehamn
Mariehamn
Mariehamn is the capital of Åland, an autonomous territory under Finnish sovereignty. Mariehamn is the seat of the Government and Parliament of Åland, and 40% of the population of Åland live in the city...
where they were supposed to spend the night and then return to the ship in the morning. They didn't learn until morning that the combination had sunk.
Although Herakles-Bulk did not declare an emergency or send a distress signal, MRCC Turku asked the Swedish search and rescue helicopters to maintain readiness in case the remaining crew had to be evacuated. Another Super Puma operated by the Finnish Border Guard, OH-HVG, took off from Turku and, after flying past Herakles-Bulk, landed in Mariehamn to wait with its engines running. The Finnish helicopter performed another flyby after the port engine began overheating.
MRCC Turku handed over the operational responsibility to MRCC Göteborg at 21:58 and shortly afterwards Herakles-Bulk requested the evacuation of the remaining crew. MRCC Göteborg gave the mission to OH-HVG, but MRCC Turku requested a Swedish search and rescue
Search and rescue
Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...
helicopter Rescue 996, a Sikorsky S-76
Sikorsky S-76
The Sikorsky S-76 is an American medium-size commercial utility helicopter. The S-76 is powered by two turboshaft engines, which drive both the main and tail rotors, each with four blades...
operated by Norrlandsflyg
Norrlandsflyg
Norrlandsflyg AB is a Swedish helicopter operator which provides search and rescue under contract with the Swedish Maritime Administration and air ambulance services for Västra Götaland County. The company has its headquarters and technical base at Göteborg City Airport and helicopters stationed...
from Sundsvall
Sundsvall
-External links:* - Official site from Nordisk Familjebok - Sundsvalls tourist information bureau. - The alternative guide to Sundsvall. - Blog with photos from Sundsvall....
, to be sent to the scene to assist with the evacuation. When OH-HVG arrived on the scene at 22:45, it was decided to lift the remaining crew members, the chief officer, the second officer and the second engineer, from the sea due to the large motions of the drifting combination. Herakles-Bulk was just two cable lengths (0.2 nautical mile (0.3704 km)) from the Grundkallen lighthouse when the captain left the ship. As he and the Finnish rescue swimmer
Rescue swimmer
The term rescue swimmer may be applied to any number of water rescue professionals, in coast guards and militaries operating around the world....
were engulfed by a wave, the cable was severed and both men had to be rescued by the Swedish helicopter.
Causes
The foundering of Herakles-Bulk was a result of loss of steering ability which was caused by malfunctions in the main engines due to severe weather conditions. Since no engine parts were recovered from the wreck, the investigation board could not determine a definite cause of the engine problems.Engine failure
The most likely reason for the overheating of the port engine was the plate heat exchangerPlate heat exchanger
A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids spread out over the plates. This facilitates...
getting clogged by small pieces of coal that had washed overboard from the cargo hold and entered the cooling system via the port side sea chest. The starboard engine was not affected because it used a separate sea water intake in the bottom of the vessel. Another possible cause was the development of hairline cracks in the cylinder liner or head
Cylinder head
In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...
due to large variations in engine load, allowing hot exhaust gases to mix with the cooling water.
Since the starboard engine ran normally after it was decoupled from the reduction gear, a likely reason for the sudden drop of engine speed from 1000 to 270 rpm and subsequent stalling when reconnected was increased load in the propulsion system due to damaged shaft bearing or a foreign object, perhaps something that had fallen from the deck, wedged in the propeller duct
Ducted propeller
A ducted propeller is a propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and are especially used on heavily loaded propellers or propellers with limited diameter. It was developed by Luigi Stipa and Ludwig Kort .Advantages are increased efficiency,...
, although malfunction in the fuel supply and lubrication system due to the violent pitching of the vessel were not ruled out.
Weather conditions
On 2 March 2004 the weather in the Bothnian Sea gradually developed into a force 10 storm on the Beaufort scaleBeaufort scale
The Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort Wind Force Scale.-History:...
, with average wind speed around 25 m/s (55.9 mph; 45.9 kn) and gusts exceeding 30 m/s (67.1 mph; 55.1 kn). At midnight, shortly before Herakles-Bulk sank, the ten minute average at Svenska Högarn was 30 m/s (67.1 mph; 55.1 kn) with three second gusts of almost 33 m/s (73.8 mph; 60.6 kn). The freezing temperatures combined with strong wind and high waves resulted in fast icing of the ship structures.
In 1992 the Finnish Maritime Administration issued a wind limit of 14 m/s (31.3 mph; 25.7 kn) for Herakles due to the pusher's low engine power and poor performance in heavy weather. The shipping company also had its own instructions regarding the safe operation of the pusher-barge combination. The wind limit was removed in 1993 for cargoes other than the ore concentrate by the Finnish Maritime Administration, but captains were obliged to follow the instructions given by the shipping company. The captain of Herakles-Bulk was aware of the limitations given in the past, but thought that they had been revoked after the engine upgrade in 1995. According to him and the rest of the crew the pusher had successfully sailed in similar or even heavier weather in the past.
The wreck
As the wreck was later inspected it was found out that when the combination sank, the coupling devices failed and Herakles separated from Bulk. The pusher, found lying on its starboard side in the depth of 25 metres (82 ft), apparently capsized while still within the notch of the barge. The superstructure was torn away and the upper wheelhouse was not found. The hull had ruptured and half of the engine room was destroyed, scattering pieces of machinery in a large area around the site. The barge had broken in two, with an approximately 95 metres (312 ft) long section lying on an even keel only tens of metres from the lighthouse. Part of the side structure and a ramp protrude above the surface. Another section, approximately 60 metres (197 ft) long, was about 300 metres (984 ft) south-southeast from the lighthouse, with the forecastle of the barge protruding in an oblique angle above the surface. The cargo of coal had disappeared from the hold. The wrecks do not pose a hazard to navigation.Herakles and Bulk were removed from the Finnish merchant fleet on 13 January 2009.
Grundkallen lighthouse received superficial damage when the combination collided with it.
Environmental damage
According to the tank situation report filed by the shipping company Herakles contained approximately 86 cubic metres (541 bbl) of marine gas oilFuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
(MGO) in eight fuel tanks, 2.5 cubic metres (16 bbl) of lubrication oil and 0.5 cubic metres (3 bbl) of hydraulic oil at the time of the sinking. There were also 70 tons (approximately 70.7 cubic metres or 445 bbl) of heavy fuel oil and 60 cubic metres (377 bbl) of marine gas oil in the fuel storage tanks of Bulk, and some fuel and lubrication oil in the generator room.
On 4 March, one day after the sinking, Swedish Coast Guard
Swedish Coast Guard
The Swedish Coast Guard is a Swedish civilian government agency tasked with:* maritime surveillance and other control and inspection tasks as well as environmental cleanup after oil spills at sea....
arrived on the scene and on the following day sent a remotely operated vehicle
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...
to search for oil in the wreck. Alfons Håkans's own tugboat Turso also arrived at the scene on 6 March and divers were sent to assess the damage of the wreck. Difficult ice conditions stopped the diving operations several times.
Swedish Coast Guard detected an oil slick with an approximate diameter of 350 metres (1,148 ft) drifting west of the island of Bodskär on 8 March. Clean-up began on the following day from the shores of Bodskär, Rödskär and Garpen islands where oily ice was collected into containers to be melted. During the following days several vessels of the Swedish Coast Guard arrived at the scene and began the difficult task of collecting and separating oil that had mixed with drift ice
Drift ice
Drift ice is ice that floats on the surface of the water in cold regions, as opposed to fast ice, which is attached to a shore. Usually drift ice is carried along by winds and sea currents, hence its name, "drift ice"....
. By 17 March three vessels had managed to collect only 5 cubic metres (31 bbl) of heavy fuel oil. Later more oil was also found around Hållet and Blåbådan. Some heavy fuel oil from Bulk and flotsam was also found on the shores of various islands near Eckerö in April.
Later inspections revealed that nearly all tanks in both Herakles and Bulk had ruptured, spilling their contents to the sea. On 1 April Turso removed approximately 4 cubic metres (25 bbl) of fuel oil and 500 liter of hydraulic oil from the generator room of the barge, but in the end some 200 tons of oil remained in the sea.
Technical details
As built, the Into was fitted out with standard towing equipment, including a 700 kN towing hook, 245 kN towing winch and 600 m (1,968.5 ft) of towing cable (⌀ 40 millimetre). Propulsion power was provided by two 6-cylinder Ruston & Hornsby ATCM 4-stroke diesel engines, each producing 1074 kW, driving two propellers, giving the tug a service speed of 13 knots and bollard pull of 255 kN. For manoeuvring she also had a bow thruster. Being a salvage tug, the Into also had VK 150/6000 water and foam monitors with a range of 90 metres (295 ft).Conversion to pusher
In 1991 the Herakles was converted to a pusher vessel by Oy Laivateollisuus Ab, Turku. The conversion also included refitting the existing barges with new coupling devices since Herakles, having considerably smaller breadth than the original Finnpusku pushers and a different hull shape, was incompatible with the original rigid three-point WärtsiläWärtsilä
Wärtsilä is a Finnish corporation which manufactures and services power sources and other equipment in the marine and energy markets. The core products of Wärtsilä include large combustion engines...
Marine Locomotive coupling. Herakles and the barges were fitted with Japanese
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
Articouple K articulated coupling system that, by forming a hinge between the two vessels, allowed free pitching of the tug relative to the barge.
The most visible change to Herakles was a new wheelhouse installed on top of a cylindrical pillar housing a spiral staircase, 14.2 m (46.59 ft) above the old superstructure. The original bridge was retained in full operating condition and could be used when the vessel was not pushing a barge. The forecastle was modified and strengthened to accept Articouple KD-350S hydraulic couplers, later installed in Turku Repair Yard, on both sides of the superstructure. Other changes included the removal of the towing winch and installation of a new auxiliary diesel generator, Caterpillar
Caterpillar Inc.
Caterpillar Inc. , also known as "CAT", designs, manufactures, markets and sells machinery and engines and sells financial products and insurance to customers via a worldwide dealer network. Caterpillar is the world's largest manufacturer of construction and mining equipment, diesel and natural gas...
DITA 3512 producing 807 kW, inside the former cargo hold aft of the superstructure to power the bow thruster of the barge. The propulsion gear was upgraded by installing new rudders, steering gear, Vulkan EZR elastic couplings, KaMeWa propeller blades and propeller ducts. The total cost of the conversion was FIM 10 Million.
The conversion increased her gross
Gross tonnage
Gross tonnage is a unitless index related to a ship's overall internal volume. Gross tonnage is different from gross register tonnage...
and net tonnage
Net tonnage
Net tonnage is a dimensionless index calculated from the total moulded volume of the ship's cargo spaces by using a mathematical formula...
from 600 GT and 180 NT to 621 GT and 187 NT, respectively. The refitted pusher was classified by Det Norske Veritas
Det Norske Veritas
Stiftelsen Det Norske Veritas is a classification society organized as a foundation, with the objective of "Safeguarding life, property, and the environment". The organization's history goes back to 1864, when the foundation was established in Norway to inspect and evaluate the technical condition...
with class notation +1A1 R280 Pusher/Tug ECO ICE 1B, meaning that her Finnish-Swedish ice class
Finnish-Swedish ice class
The Finnish-Swedish ice class is an ice class assigned to a vessel operating in first-year ice in the Baltic Sea and calling Finnish or Swedish ports...
was reduced to 1B from the original 1A.
The remaining towing and salvage equipment was retained for some time after the conversion so that, if necessary, Herakles could perform normal tug duties while not employed as a pusher. However, it appears that they were later removed completely as the towing gear was no longer listed for Herakles on Alfons Håkans's website unlike with the rest of the tug fleet, making her purely a pusher vessel.