This is one of the fields in whichHydrex works to assist owners toovercome the problems that arisewhen repairs are necessary. Hydrexteams can perform most jobs in-situ,presenting a major saving in time andmoney as the offshore unit does notneed to go off hire to be taken to dry-dock.
This month’s magazine features anarticle on a job carried out last monthwhich required meticulous planningand engineering skills combined withprofessional diving expertise. Thearticle shows the value of advancedunderwater repair and replacementknowhow.
At the end of the day our goal is always to satisfy the needs and requi-rements of the owner while getting thework done as quickly and economi-cally as possible.
In-situ repair of 40 ton azimuth thruster oncrane barge in Gabon
Table of contents
In-situ repair of 40 ton azimuth thruster on cranebarge in Gabon 4-9
ISO 9001 certified
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When one of the four 40 ton
swing-up azimuth thrusters
of an offshore crane barge which
was servicing rigs on an oil field off
the coast of Gabon malfunctioned,
Hydrex was called in to remove the
thruster and perform the necessary
repair work while the unit stayed at
anchorage just outside the field.
While it is possible to maintain location with three thrusters, thefourth needed to be repaired straightaway. This had to be done in the shorttimeframe in between two scheduledoperations. The barge could onlyleave the oil field in this period and all repairs and other servicing workneeded to be carried out before thestart of the next operation.
In-situ repair of 40 ton azimuth thruster on crane
barge in Gabon
Work barge with 25 ton mobdock and support unit for the thruster
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Support unit lowered into the water
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Very fast mobilization
A similar operation had been plannedand carried out by Hydrex three yearsago. Just as with the recent operation,going to drydock had not been anoption as the nearest suitable locationwas South Africa and this would have taken the repairs far beyond theavailable time frame. For this reason alarge mobdock (measuring 9 x 6 x 2metres and weighing over 25 tons by itself) was constructed underHydrex supervision in Belgium afterwhich it was transported to Gabon.There it was stored after the repair to be used at short notice wheneverfuture repairs were required on thethrusters. This allowed for a very fast mobilization and execution of theoperation which was carried out lastmonth.
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Mobdock lifted from the pontoon…
and lowered into the water
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carried out satisfactorily. The offshoreunit was fully operational again, wellbefore the start of its next operation.This presented a major saving in timeand money for the owner as the off-shore unit did not have to go off hireto be taken to drydock.
It was an extremely precise operationrequiring a great deal of coordinationand organization to ensure that allwent smoothly. There were detailedsafety and technical procedures thathad to be met in order to access thethruster from within the engine roomas the thruster was located outside thevessel under the water line. Despitethis, all technical work was performed
First an operations base was set up ona work barge next to the crane barge.The mobdock was then installed andall water was pumped out of it to create a dry working environmentunderwater. The water sensitive partsof the thruster were then sealed offafter which the mobdock was remo-ved. The thruster unit was loweredonto a special support unit under thebarge and brought to the work barge.
In-situ thruster repairs and
reinstallation
Subsequently Hydrex engineers dismantled the thruster under thesupervision of a representative of the manufacturer. The entire gearingwas taken out, thoroughly checked,cleaned and reinstalled. The thruster’spropeller was disconnected in its entirety and replaced by the propellerof a spare thruster that had also beenbrought onto the barge. The sparethruster (together with the old propel-ler) was then brought to shore fortransportation to the workshop whereit would be overhauled. Once it isreturned the owners will have a fullyoperational thruster ready to be instal-led if another breakdown should occurin the future.
Meanwhile the fully checked originalthruster with its new propeller wasreinstalled into the crane barge follo-wing the reverse procedure. Finallycommissioning and testing was
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40 ton thruster lowered onto support unit
Gearing taken out of thruster…
and reinstalled after being fully checked and cleaned
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smoothly by qualified Hydrex diver-technicians. They worked in shifts tofinish the operation as soon as possi-ble and without any loss of quality.
New office in Gabon
Concurrently with this operation thelatest step in the Hydrex expansionplan was executed close by in PortGentil, right next to Cape Lopez Bay,where a new Hydrex office was opened.
Port Gentil offers safe anchorage forall types of vessels (up to ULCC) on asand/mud seabed with depths up to 50 metres and more. Thanks to thesheltered environment of the bay theswell is limited. This makes it the bestlocation to carry out repair or main-tenance work on a ship, barge or rigand this in ideal conditions.
The central location on the AfricanWest coast makes Port Gentil the idealplace for a logistic and equipmentsupport base for the entire region. Thisallows the new Hydrex office to also mobilize to any other suitablelocation in West Africa in a very shorttimeframe, making both emergencyand scheduled operations possible.
As a consequence of the warm waterssurrounding the African continentthere is an increase of fouling on vessels sailing in these regions. Likeall Hydrex locations, the office in Port Gentil is equipped with a full setof the Hydrex patented underwaterhull cleaning equipment. This enablesHydrex to offer a very fast and effi-cient hull cleaning service to vesselssailing in the region.
There is a lack of available drydocksin West Africa. By carrying out repairand maintenance work in-situ Hydrexsaves shipowners not only the troubleof having to find one, but also the lossof time and money docking bringsabout.
All maintenance and repair work willbe carried out following the necessarysafety measures and according to theclass approved Hydrex procedures.Working closely together with theheadquarters in Antwerp the office
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Spare thruster unit brought onto work barge
Oil removal from spare thruster unit
Fully checked thruster with new propeller ready to be reinstalled
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can benefit from the company’s longtradition in the ship repair and offsho-re industry.
Comprehensive offshore repair and
maintenance services
Besides the thruster operation described in this article, Hydrex hasdeveloped the technology to removeand repair a variety of thruster typeson site. Thrusters are a vital and integral part of most vessels and espe-cially so to many DP offshore units.Going off hire for repairs causes serious disruption to an offshore operation resulting in a significantloss of time and production.
Diver preparing the mobdock for installation
Diver preparing the inside of the mobdock for installation
Work inside the engine room
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Hydrex also has solutions for theimmediate repair or replacement of a wide range of other underwaterequipment, such as stern tube sealreplacements, cathodic protection,sounders and transducers, as well ascorrosion and damage repair. Depen-ding on the circumstances, much ofthis work can be carried out in-situwhile the unit is stationary and ofteneven while production is still ongoing.With preventative engineering and theconstruction of repair equipment inadvance, delays can be eliminated orreduced significantly. The Hydrexgoal is to manage and perform thiswork with the least disruption possi-ble. All used methods are permanent,effective and long-lasting.
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Bolts screwed after reinstallation of azimuth thruster
The barge was servicing rigs off the coast of Gabon
Diver entering the water
Bolts secured to complete thruster repair
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Hydrex worldwide uand maintenan
Hydrex provides a compre-
hensive range of underwater
maintenance and repair services
to the ship owner and offshore
industry.
Saving significant amounts of time,trouble and expense thanks to in-situwork, the offered services range froman inspection of an external conditionand any required maintenance or clea-ning work all the way through to high-ly technical major repairs or replace-ments of a ship’s external underwaterequipment and machinery. Repairs to
thrusters, propellers, rudders, sterntube seals, damaged or corroded hullsand all other underwater services arecarried out by professional teams trai-ned and qualified to perform complextechnical tasks underwater while thevessel is in-situ. Working closelytogether with owners, managers andsupervisors, all used methods are fullyapproved by all major classificationsocieties.
Throughout Hydrex’s history the com-pany has always been at the forefrontof technological developments in its
field, having won many awards for itsapplication of the cofferdam principle,now known as “mobdock technology”(mobdock being short for mobile minidrydock).
Hydrex is renowned for bringing dry-dock like conditions to the vessel andoffshore unit. This helps owners toextend their vessel’s drydock intervaland gets rid of the loss of time andproduction docking brings about.
The Hydrex headquarters are seated inthe Belgian port of Antwerp where the
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11
de underwater repairenance services
company was founded over 35 yearsago. Recently offices were opened inTampa (U.S.A), Algeciras (Spain),Mumbai and Visakhapatnam (India)and Port Gentil (Gabon). All officesare ready to mobilize immediately. Aspart of the Hydrex group they can takeadvantage of the main office’s expe-rience in the shipping and offshoreindustry.
The Hydrex in-situ repair service wasonly the first step in the drydock inter-val extension service as it is offeredtoday by the Hydrex group and was
followed by the development of theEcospeed coating system.
Ecospeed is a technology. It consists of an impermeable andextremely tough coating that is comb-ined with an underwater cleaningsystem keeping the hull roughness atan optimum level and resulting in amajor saving in fuel. The decrease in fuel consumption thus obtained,combined with the fact that Ecospeedis a 100% non-toxic technology con-
tributes to the reduction of carbonfootprints. The coating is guaranteedfor 10 years. Its surface texture willimprove over time with regular in-water hull maintenance.
Ecospeed ship hull performance tech-nology lasts the lifetime of the vessel.The need for full repaints during future drydockings is eliminated. Thisis another important step towards realizing the current trend of develo-ping ways of prolonging drydockintervals from the current maximumof 5 years to a period of 10 years.
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Keeping ships in business
Hydrex underwater tech-
nology and services
provide high quality solu-
tions to the repair and repla-
cement problems encoun-
tered by ships and offshore
vessels.
We deliver a complete line of
services that may reduce oravoid off-hire time entirely.From major projects to simpleinspections, Hydrex has theworldwide facilities and capa-bility to meet your demands.
Drydocking is not necessaryso time, trouble and expense
are saved by doing work in-situ. Hydrex services cover highly technical majorrepairs or replacements of a ship’s external underwaterequipment such as thrusters,propellers, rudders, stern tubeseals and damaged or corrodedhulls.
