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36Consultants, Naval Architects and Marine Engineers

New telephone numbers

in order to support our growth and to provide our customers a quicker and direct access to our employees, we have installed a new telephone system.

From the end of november 2011 all our employees have a direct number. You can reach VEr on the following numbers:

main phone number: +3110 760 16 00Fax: +3110 760 16 99

our old phone number and fax number will remain available.

this Vuyk today no. 36 offers you an overview of our most recent projects and developments. if you have questions about these projects or developments, please contact us.

november 2011

Han Holtackers / technical director

on 1 January 2005 i took up the challenge to lead Vuyk Engineering rotterdam (VEr) as managing director. it was indeed a challenging time with lots of developments. Since then the number of employees has grown by more than 50% and the turnover has almost doubled over the same period of time. during all these years we also managed to realise a healthy profit. the type of work has changed; aside from the traditional drawing works we added a lot of arithmetical analyses in the areas of structural strength and hydromechanics.

new clients were added to the existing client base, especially clients in the offshore and marine opera-tions sector found their way to our company. Lots of market changes, remember the financial crisis which started in 2008 and is still going on, this changed the world of large investments with consequences for all involved. as from 2008, iHC became our shareholder. it was a fascinating time. thanks to all who supported me!

the latest important change has been a change of management. Where historically our company was headed by one director, as from 1 may 2011 this was changed to two directors. i asked marc oele, formerly employed as deputy director, to take the lead as managing director. i will continue as technical director.

marc, i wish you a lot of success with your new position!

marc oele / managing director

Successful companies have to look forward and develop constantly. this is certainly something that Han Holtackers has done during the past years. When he asked me to take over his position i therefore had no doubts. i joined Vuyk Engineering rotterdam in 2005 as a project manager and soon became involved in management tasks as deputy director. We have constantly developed ourselves, in parallel with the needs of our clients, towards more challenging, complex and demanding projects.

at this moment of taking over the helm, i am sure which course we are heading. the ship is in good shape and with a well trained and eager crew. the future is unclear as ever, but we know that we have developed very good relations with a large group of very loyal clients. these strong relations have kept us afloat in more difficult times. the success of VEr is built on working very closely together with our clients and to assist them in achieving their goals. You can be sure that we will not change this approach.

to be of better service we have decided to expand our workforce to about 60 engineers and at the same time develop the organization to a more professional structure. Heading the company with two directors is part of that development.

i look forward to working more closely together with all of you and will take all possible opportunities for an acquaintance with those of you who do not yet know me.

PhoneFaxWebsite

+31 (0)10 760 16 00+31 (0)10 760 16 99www.vuykrotterdam.com

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CoLoPHonVuyk today is published by Vuyk Engineering rotterdam B.V., P.o. Box 1, 2900 aa Capelle a/d iJsselthe netherlands

Layout and productionVuyk Engineering rotterdam B.V.Virtek

TextVuyk Engineering rotterdam B.V.

PhotographyVuyk Engineering rotterdam B.V.Various clients

PrintingSegers offset Schiedam

We thank our clients for their contribution to this newsletter.

ContEntS

riSEr aCCESS toWEr

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ALE Heavy Lift installs first shell sweep

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the riser access tower, rat, is a relatively small platform mounted on a tubular which is supported on the seabed through suction piles. the connection with the platform is made with a gangway construction. the current total platform has a height of about 55 m. the suction can configuration is about 16 x 16 m with a bucket height of 7.0 m.mercon Steel Structures built the rat at their yard in gorinchem.

although the structure is obviously optimized for its installed purpose, the shape is difficult to transport and install by other means than using a large offshore installation vessel which is relatively expensive for the weight involved. Suspending and lowering it with a sheerlegs or from a barge bow or stern seems a good alternative. However, the rat is quite high and the platform location is relatively far from shore for transportation whilst suspended. Fixation of the rat with the suction cans (partly) submerged during transport would introduce too high loads in the structure in reasonably high environmental transport conditions.

Being a practical and ingenious heavy lift contractor, aLE decided to “simply” transport the rat horizontally whilst fixed on an upending frame on the barge. thus transport in considerable wave heights became feasible. on site, the upending frame was skidded aft and turned the rat upright after which it was lowered using strand jacks mounted on the same frame. in order to limit the loads on the rat and frame due to barge motion and wave action, the suspension point was made hinged. thus the rat could rotate around the two horizontal axes. the total of functions of the frame, supporting, skidding, upending, hinging and fitted with strand jacks made it indeed an ingenious piece of equipment.

aLE Heavylift approached VEr for assistance in determination of the dynamic loads and motions for the transport and installation process. With the help of 3d diffraction software aQWa, the behavior and accompanying loads were deter-mined through single and multi-body analyses in both frequency as well as time domain including non-linear morison load effects.

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determination of the allowable wave heights for this type of installation is not as straightforward as it seems. the rat goes through several stages with each new limitation: support loads during transport, skidding loads, upending frame connection loads, possible wave slam on the suction cans, suspension loads in the hinged connection, wire loads during lowering and possible wire snatch loads during the seabed penetration process. Each of these stages has its specific limitations.

the method was also new from a motion point of view. Kuno van den Berg (project manager for VEr): “although we have ample experience with transports and heavy lifts offshore, above water or submerged and have performed numerous analyses for this purpose, the rat did surprise us. the motion period of the upended rat and the barge yaw could excite each other, which resulted in quite complicated motion behaviour of the rat-barge combination. in marine operations, very exact answers are not the main interest as the conditions are in reality always somewhat different. it is therefore important to know the parameters involved and their influence as to determine the boundaries for safe operation.”

VEr also designed the catenary mooring. as the mooring had an influence on the rat-barge motion combination, a simplified mooring pattern with comparable stiffness characteristics as the actual one was used in the dynamic calculations.

Elena Stizza (engineer responsible for the analyses): “By making simplified models and studying multiple suspension methods and mooring com-binations in aQWa, we were able to get a good understanding of the phenomena involved and discuss them with aLE, Shell and gL-nd. Based on our results aLE was able to optimize the upending, suspension and lowering equipment and get the dynamic design loads. at last the allowable wave heights could be determined.”

End of august 2011, the rat was successfully installed. it shows that with proper preparation and good cooperation, new installation methods will pay off. We hope to work with aLE Heavy-lift again.

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as Vuyk Engineering rotterdam (VEr) we always try to fit the client’s needs within our capabilities. Sometimes it means we have to develop new methods and tools, and sometimes it means we can use third party software that fits the needs. in recent years we have become increasingly involved in offshore projects, mooring analyses, monopile installations and riser configurations for mining tools. Because almost all marine operations have become more demanding and complex, we started using orcaFlex. We see lots of possibilities to apply this tool in future projects of existing clients.

orcaFlex is a ‘fully 3d non-linear time domain finite element program’. it is basically meant for analysing riser and mooring line configurations, this in combination with floating structure inter-actions. Four examples show the extensive engineering possibilities using orcaFlex.

the orcaFlex package is capable of modelling all kinds of marine operations in an open water environment, from (subsea) lifting operations till time domain failure analysis of moored structures. as an example, the complete mooring and riser

configuration connected to a semi-submersible can be analysed under a large set of environ-mental conditions. this analysis can cover all kinds of interactions, like ship motions, wave loads, wave drift, wind and current effects.

By simply increasing the stiffness of the line elements, it is for example possible to create a model of a stinger construction. in this way it is possible to evaluate the loads in the stinger as well as in the cable/pipe during cable/pipe lay operations in a time domain analysis.

Simulations of lifting operations or installations of (subsea) structures like monopiles and spar shaped objects can easily be performed for large sets of environmental conditions. By visualizing the results in video clips, the client will get a better understanding of the motions.

orCaFLExextending our Marine Operations capabilities

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in combination with the natural frequencies it is possible to explain to the client why a structure will react highly to a set of waves with a typical wave period, and what can be done to reduce the wave induced motions.

at the moment of writing we are pushing the limits of orcaFlex further by modelling the wave response of a backhoe dredger, which normally operates as a partly out of the water jacked barge on spuds. With this approach, the loads in the spud hoisting wires and spuds can be analysed in a realistic approach.

Our factor

Because the capabilities of orcaFlex are massive, so too is the amount of calculated results. at VEr we aim to present the client the results in summarised, useful and understandable way in combination with advise for improvements where possible. We also work in close cooperation with the client to ensure efficient use of our knowledge. this also includes 3d visualisations of the results for better understanding of the calculated results. on our website some video clips can be found showing the four discussed examples.With the introduction of orcaFlex, alongside our other software packages including aQWa and many other software tools, we have extended our marine operation analysis capabilities to meet current and future demands. Feel free to contact us for more information about our marine operation capabilities.

Recent projectsmooring analysis for a semi-submersible –crane vessel, including failure assessment and clearance calculations.monopile installation –Ultra deep water deployment operations –deep sea mining operation analyses –multiple riser catenary optimizations –non-self-supported composite riser system –analysis

Future projectsBackhoe dredger spud load analysis in time –domainriser Launch and installation operations –Vortex induced Vibration (ViV) analysis –

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inspired by the flight simulator at the technical University delft which simulates 6 degrees of motion through an actively controlled hexapod cylinder set-up, the stewart platform, the founders thought to turn that function around and have the stewart platform follow the 6 degrees of motion of the platform it is mounted on, a moving vessel in a seaway. thus keeping the transfer deck and the access gangway almost completely stationary.

about one year ago ampelmann visited us in search for a consultancy, design and engineering company that could assist them in realizing their growth plans. although relatively young, founded in 2007, ampelmann is already well known in the offshore industry for their high tech offshore access system. Why? accessing an offshore platform from a floating vessel on an ampelmann is “as easy as crossing the street”.

amPELmann xL“Size does matter”

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obviously, simply increasing the length means an increase in weight and worse, an increase in moment on the hexapod. therefore VEr started the project with a concept study in optimization of the existing gangway construction and gangway luffing cylinder arrangement, with the aim to reduce weights and moments.

the company had four systems operating with success when they visited our offices. From the market, they found out that “size does matter”; the ampelmann needed to be modified from a gangway length of 20 to 25 m, and the upward maximum angle needed to increase from 20 to 45 degrees. in principal, no problem for our engineers. However, as for most of Vuyk Engineering rotterdam’s projects, there was a catch: the heart of the system, the stewart platform was not to be touched.

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With the new cylinder arrangement came new arrangements of the control box and with the new gangway a new telescoping equipment arrangement.

the above meant a completely new structural design checked with anSYS calculations, 3d mechanical designs and 2d basic design and manufacturing drawings. at last VEr assisted during building of the xL.

the project started in January 2011 and finished with a new ampelmann xL ready for offshore works at the beginning of may 2011.

managing the mentioned scope in such a short time span would not have been possible without the dedication of both the ampelmann and VEr project team in working closely together, effectively and pleasant. We hope for an ongoing cooperation.

VEr generated several concepts for the cylinder arrangement from which a non-obvious choice came out to be the best solution. it did not only mean a more favourable weight distribution but also a better gangway interface load introduction:

the gangway luffing cylinders were moved from in front and underneath the transfer deck to aft of the gangway on top of the transfer deck. this option meant that the cylinders would not be working in compression but in tension which is not a very obvious solution as cylinders are less effective in pull than in push. on the other hand, buckling of the cylinder rod is no longer an issue.

most importantly, the weight of the cylinders was now counteracting the weight of the gangway and the load introduction on the gangway was more favorable as explained next.the original load carrying construction of the gangway was the bottom part. VEr proposed to use the railing as part of the main construction. this increases bending stiffness of the gangway. the luffing cylinders were now connected directly to the railing and therefore introduced the luffing load better into the gangway construction.

to help weight reduction, the transfer deck was reduced in size and the control cabin reduced in weight.

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in a fast track design process, we succeeded in first preparing a tender package, shortly followed by a complete package of class approved basic design drawings and docu-ments, detailed to a level allowing a smooth start and execution of detailed engineering by the building yard. this allowed the client to perform the tendering and contracting phase within the intended time schedule.in July 2011 the vessel was successfully launched at the Keppel Singmarine yard in Singapore. the delivery of the roCKPiPEr is planned for early 2012. in this article we would like to provide some more information about the vessel and our input of expertise in the project.

main CHaraCtEriStiCS

Length over all 158.60 mBreadth 36.00 mdepth 13.50 mdraught 9.40 mComplement 60 personsHold capacity 15.500 m3

rock deadweight abt 24.000 tontotal installed power 15.200 kWrock dump capacity abt 2.000 ton/h

developments in the offshore market and worlds energy markets demand an ever increasing amount of infrastructure to be installed on the seabed. newly explored and often remote offshore oil and gas reserves need to be developed. Energy demand requires pipe lines and power cables to be run over long distances to provide distribution networks for gas and electricity. the opportunities for large construction works attracts offshore and dredging contractors to invest in their work vessel fleet. as a design office specializing in offshore and dredging work vessels, we have seen an increase in demand for deep water - fall pipe rock dumping vessels. in 2011 we added another design for such a vessel to our track record. in october 2010 we delivered a complete set of basic design documents for the fall pipe vessel roCKPiPEr to our long term client Boskalis Westminster.

VEr prepared the full basic design and the detailed design of some special items of the vessel for the owners. one of the main challenges of this project was the time restraint put on this project by the client.

roCKPiPErfall pipe vessel

observing the designs of fall pipe rock dumping vessels, it is striking that all operators make their own choices in vessel design, lay-out and choice of fall pipe type and system. Boskalis in this is no different. the design is in accordance with the latest demands of the offshore industry, i.e. the ship has a class 2 dynamic positioning system and SPS notation and fulfills the latest marPoL requirements.

two stone bunkers with excavator are located on the maindeck, positioned fore and aft of the fall pipe system, built over a large moonpool. the moonpool is provided with specially designed bottom doors.

to ensure the possibility of converting the vessel in the future for offshore work, the design is such that the fall pipe system and the rock bunkers can be removed to create a flat top offshore vessel. the future installation of an offshore grab has also been facilitated in the design. on top of that, the vessel is prepared for future installation of one additional main diesel generator set and one additional retractable thruster.

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For this type of vessels practice has shown that high loads in combination with discontinuities in the structure results in crack formation in the moonpool and rock bunker area. to mitigate that risk for this vessel, we performed a FEm analysis of the entire hull (so called global hull analysis) to investigate stresses near the discontinuities of side shell in way of the stone bunkers and moonpool. By careful structural design and well chosen structural details, the risk of crack formation has been significantly reduced.

another design aspect for this type of vessels is the risk of green water entering the rock bunkers. model tests have therefore been performed at marin, to determine the amount of ingress of overcoming water. Based on this result the rock bunkers de-watering arrangement has been optimized.

in our designs we notice the ever increasing effect of regulations aimed at protecting the environment. the vessel is designed with a water ballast system that can implement a water ballast treatment unit in the future. a diesel electric propulsion system is chosen. Common rail main engines are installed and the vessel is prepared for future installation of a de-nox system.

in march of 2010, Vuyk Engineering rotterdam (VEr) was asked by dutch heavy lift and salvage operator multraship in terneuzen for advice about the possibilities of an upgrade of their 400 ton floating sheerlegs Cormorant. that was the start of a project, which finished in January 2011 with the successful 600 ton load test, hanging on the new and enlarged a-frame.

Like the majority of the sheerlegs, the lifting appliance on the Cormorant from multraship is rather versatile. the main part of the hoisting equipment is the a-frame, carrying the hoisting blocks. after installing the separate jib, the hoisting wires can be reeved into the jib hoisting blocks for lifting at a higher level.

also deck winches are installed which are able to lift 400 ton, additional to the main hoists. the a-frame can be completely lowered forward, for mounting the jib or for river transit with limited height. the a-frame can also be lowered com-pletely backwards, for a safe sea transit. Lowering and upending the frame is a critical operation. during such operation in march 2010 the vessel was damaged.

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Cormorantfloating sheerlegs upgrading

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the a-frame construction was reinforced for the upgrade from 400 ton to 600 ton. a replacement of the a-frame construction was the opportunity to develop a more efficient construction and to increase the length of the a-frame. VEr determined that an enlargement of the a-frame from 35m to 43m was possible with a SWL of 600 ton. the SWL for hoisting with the additional jib could be increased from 200 ton to 400 ton.

in the next phase the basic design and detail engineering was provided by VEr. a tight time schedule required that the workshop drawings of the main construction parts were completed at a very early date. in the meantime the class approval had to be arranged. Close cooperation with multraship was necessary to determine the functionality. Because the vessel was built in 1973, it took some effort to get all the required technical information.

the fabrication of new parts started at VdS (Vlissingen) in June. VEr advised during the production phase about welding details, assembly sequence, measurements and tolerances. also some details were changed to comply with the capabilities and the available equipment at the yard.

after assembly of all new parts on the vessel, several load tests were performed in January 2011, according to the new load curves. all these improvements ensured that the revised Cormorant turned out to be a heavy duty floating crane, which satisfactorily meets the requirements of the owner.

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“Same as previous, or is it?”

By the time this issue of the Vuyk today has been printed, Seajacks UK will have installed around another 50 wind turbine generators at the Walney ii offshore Wind Park (WoWii). Vuyk Engineering rotterdam (VEr) performed all the engineering for the installation.

it is not the first time that we delivered the complete engineering package for Wtg installations. Previously, VEr did the same for robin rigg (Ves-tas turbines) and alpha Ventus (areva multibrid turbines) and part of the engineering packages for numerous other wind parks. VEr has also worked with Siemens turbines before which are now being installed at WoWii. therefore, one may say “same as previous”. But was it?

Seajacks UK had already installed the turbines for the Walney i park (not engineered by VEr) so the project could have been a copy. However, the turbines on Walney ii are bigger. therefore, towers needed to be installed in three sections instead of 2, the hub was installed separate from the nacelle and the blade rack needed to be redesigned for the bigger B58 Siemens blades.

operations and arrangements:Paul van Leeuwe (lead engineer for VEr on the project): “it is easy to put everything on deck to make it fit. What makes it a challenge each time is the interaction between lifting arrange-ment, overall weight, Cog and deck strength. therefore, we always start a project like this with a feasibility phase where the complete puzzle is solved. this means making lifting procedures to check the crane reach and clearances, moving the jack-up relative to the Wtg foundation, moving the items over deck while checking the overall weight and under deck strong points at the same time”. Kuno van den Berg (project manager for VEr on the project): “the overall weight in relation to the jacking capacity is always a critical factor in these kinds of operations. if not, an extra turbine will be put on deck. this makes the above exercise an iterative process and if the components or jack-up are not exactly the same as previous, the complete project is not either since all aspects are tied together.”

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the blade rack:due to the larger length of the blades together with the crane’s operational limits, the original blade rack did not suffice. Furthermore, from their experience with WoWi, Siemens and dong requested the layout of the walkways to be changed. therefore, the construction had to be completely revised.

in making the new design, also the top blade tip support was optimized. Paul van Leeuwe: “in the original blade rack, the top blades were suspended in fibre rope. this was, however, not very practical as this allowed for too much movement of the blades in the rack during transportation. therefore, we proposed a steel saddle on a hinge for the tip blades. By adding a counter weight, one man can easily turn the saddle.”

after all preparations, VEr also assisted in the lifting arrangement for mounting the new blade rack and during mobilization.

Kuno van den Berg: “operational projects like these involve a lot of communication in a short time span between all parties and personnel involved; engineers, barge masters, manufac-turers, etc. a good cooperation is vital in order to limit engineering iterations, to get information as soon as possible and to make the decision making processes as effective as possible. Seajacks UK managed this process well and was a pleasure to work with.”

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in studying the existing systems as well as the typical operational requirements for the installation platforms the new VEr jacking system was developed. it is based on a rack and pinion system to obtain the speed advantages of this system but it is designed in such a way that it is not required to have expensive racks over the full length of each leg.

VEr JaCKing SYStEm

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research & development

Vuyk Engineering rotterdam (VEr) has invested quite extensively in research and development projects. the main focus for r&d has been on the (renewable) offshore market. VEr has completed a lot of projects with various clients in the wind turbine installation market and has gained through these projects good knowledge and experience on the requirements in this market. this has been the starting point for further developments in various fields.

one development is related to jacking systems. For the present wind turbine installation platforms mostly hydraulic jacking systems are applied. traditionally in the oil and gas platforms a rack and pinion system is used. Both systems have proven themselves over the time but in analyzing them, both also contain points of improvement. For the oil rigs the rack is applied over the full length of the leg which adds up to quite an investment. the hydraulic jacking system is highly dependent of the cylinder speed and the buckling limitations of the cylinder rod. and especially for wind turbine installation platforms jacking speed and stroke are important operational parameters.

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it contains a double acting set of racks. When the legs are moved up or down, this is a linear movement over the working rack. in the same movement the idle rack moves simultaneously in the opposite direction, ending at its initial position. By taking over and switching from working rack the movement can be repeated again. the system is flexible in the sense that the number of driving rack and pinions can be adjusted to the required lifting capacity and the stroke can be designed to the operational demands. in this way the VEr jacking system can be designed to suit each required lifting and holding capacity, stroke and speed.

patent pending

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locking pin

planetary gearbox6 in circumference

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leg

general overviewouther casing not shown

general overview of jacking

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turning directionplanetary gearbox

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main CHaraCtEriStiCS

Length over all 120.00 mBreadth 35.00 mdepth to main deck 9.50 mdeadweight 11 000 tonmain engines 4x 4 200 kWSpeed 15.5 kn

With the expansion of wind turbine parks offshore the need for connecting all these power generators to shore also increases. Within a field all wind turbines are connected by array cables and in the end a power cable is brought to shore. Vuyk Engineering rotterdam has performed a market study into the tendencies that can be seen in the near future and the requirements for laying all these power cables.

From the results of this market study the design requirements for a power cable lay vessel were deducted and a concept design was made. the focus for this concept design has been on the equipment side. the number of power cable suppliers is limited so deadweight is an important issue. the number, capacity and size of the cable reels is carefully selected, also considering the type of cable and its laying process. in the end combining the operational process with all equipment related requirements has defined the layout of the equipment and corresponding deck layout.

together with other concept developments such as complete wind turbine installation vessels that have already been reported in previous issues of the Vuyk today, but also in the deep see dredging and mining, you can see that Vuyk Engineering rotterdam can serve you in any field of the market for renewables.

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From the tests it was derived that the ultimate load of the notched specimen (F_ult, being the top value of the curve in figure 2) was equal to the material’s tensile strength (as measured) times the net section area in way of the eye. this is exactly the same as what is valid for ordinary (uniformly stressed) tensile specimen.

therefore, it was concluded that a stress concen-tration does not affect the ultimate load bearing behavior of tensile specimens, valid up to S690 material. this conclusion was supported by the observed fracture surfaces, figure 3, which resemble the same (ductile) failure mode as occurs with uniform specimens.

Back to pad eyes having a design peak stress up to yield. Knowing that the ultimate load can be taken as Fult = rm x a (where rm is the tensile strength and a the section area corrected for the eye), a check on ultimate strength is only necessary when:

the ratio of yield point (re) to tensile strength (rm) typically ranges from 0.6 to 0.9 for S235 to S690 qualities. Stress concentration factors for common pad eyes (SCF) typically amount up to 4. Common safety factors with respect to ultimate load (ŋult) typically amount to 3. in most cases the ultimate strength requirement can be met while designing on yield, also for the more unfavorable combinations (high strength – low stress concentration).

in Vuyk today issue 32 we already reported on an r&d project investigating pad eye stress calculations. the project was driven by trends in present-day pad eye designs, where increasing load levels lead to high demands for structural optimization and the application of higher strength steels. these aspects could not be addressed satisfactorily by the methods then available. Based on extensive finite element analyses Vuyk Engineering rotterdam developed a practical (excel) design tool for ac-curate calculation of the stress peaks governing pad eye designs. applying this method (designing up to the yield limit at the stress peak location) improves the ability to save material while main-taining structural safety.

However, designing on local yield requires an ultimate strength check. a follow-up r&d project was initiated to find out about pad eye ultimate loads, especially with respect to the application of higher strength steels (up to S690).

in order to get a grip, we did a number of tensile tests, in cooperation with delft University, see figure 1.

Flat bar specimens were prepared in steel qualities S235, S355, S460 and S690 with a central circular hole, in order to simulate the stress concentration effect in a pad eye. the same base material was used to test ordinary tensile specimen, providing us with all the necessary material properties. Figure 2 shows a typical load – displacement curve as recorded during the tests of the notched specimens.

Pad EYES

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Figure 3

Figure 2

a pad eye design will be governed by ultimate strength only in cases with high safety require-ments to ultimate (e.g. exceeding a factor of 3) and / or low stress concentrations, the more for the higher strength materials. actually, a high stress concentration is favorable for (static) strength, especially for higher strength steels. reason for this is that the large strength reserve in sections with high stress gradients is used to compensate for the typical lower strength – yield ratios of higher strength materials.

Final conclusion is that high strength materials can be efficiently and safely applied for pad eyes which are predominantly statically loaded (i.e. no fatigue issues). Prerequisites are an accurate calculation of the stress peak and checking the ultimate limit. this knowledge gives the opportunity to minimize material usage (thickness) in balance with material selection (quality), while maintaining sufficient structural integrity.

Full details on the research can be found in a recent VEr publication as presented at this year’s omaE conference, see note. this publication includes a theoretical basis applying damage mechanics theories which can be used to predict the moment of ductile failure. these theories are of particular use when the ultimate load cannot be calculated by the product of ‘rm’ and ‘a’, e.g. in case of brackets which are embedded in larger (ship) structures.

m. Verdult, r. marchee and g. Hommel: ductile Failure Limit State design of High Strength Steel tension members with Large Stress Concentra-tions, 30th international Conference on ocean, offshore and arctic Engineering (omaE2011), new York City, US, american Society of mechanical Engineers.

Figure 1

Spud carriers increase the efficiency of cutter and wheel dredgers. over the years Vuyk Engineering rotterdam has been involved in the designs of these carriers for all types of small and large dredgers. We have become specialists not only in designing new equipment, but also in giving advice on modifications to existing spud carriers. Some spuds are hoisted by cylinders and slings while others use wires and sheaves close to the spud points. Some spuds are not tiltable and others have advanced spud tilting installations. generally speaking the more simple designs are for smaller, mostly dismountable dredgers and the more complicated designs are for seagoing equipment. these dredgers work in coastal areas meeting wind, current and tidal conditions.

one other type of carrier to be mentioned is the one for the backhoe dredgers. the function of this carrier is different from that of the cutter dredgers. the carrier does not swing around one pivot point, but just moves the dredger to the next working area. travelling is done by winches or cylinders, where the cutter spud carrier always works with hydraulic travelling cylinders.

Pictures 1 and 2 show carriers of small, dis-mountable cutter dredgers. the wheels are in fixed shafts and the guiding taking the transverse forces are just steel flat bars. Both carriers have spud doors, but the spuds cannot be tilted.

Pictures 3 and 4 show a carrier for a medium sized dredger, designed to work in harbour and river entrances, so coping with tidal areas and relevant wind and currents.

the carrier is equipped with two transverses which enable the vertical wheels to take the vertical forces and the horizontal guiding brings the transverse forces in the hull. the spud is hoisted by cylinder and sling, no tilting provisions have been arranged so far.

SPUd CarriErSfrom small to complicated designs

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Picture 1

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Picture 5 shows a study impression for a carrier with a sea condition compensation system. the system works with wires and tensioners, keeping the carrier in a vertical position. a separate spud tilting system will be provided.

on picture 6 one of the most recent designs is shown. this carrier, designed for a 2200 mm diameter spud, travels with one pair of slides at both sides. the vertical position will be maintained by two pairs of hydraulic cylinders, taking all horizontal forces which occur during the cutter process. all cylinders are cardan hinged mounted. the spud is hoisted by hydraulic cylinders and a clamp. a separate spud tilting installation has been mounted for tilting the spud into a horizontal position during sea transport.

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Picture 3

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Picture 7 shows a design impression of a more or less conventional spud carrier with two transverses, splitting horizontal and vertical forces to the hull. Spud tilting is done by tilting the complete spud guiding house with hydraulic cylinders. the spud is hoisted by winch and sheave in the lower part of the spud. Pictures 8, 9 and 10 show some details of this impressive construction.

as already mentioned, also some backhoe dredgers are equipped with spud carriers. Picture 11 gives an impression of such a carrier, in this case with an auxiliary hoisting system.

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Picture 7

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Picture 11

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SCH 123 ’ZEELand’ upgrade

this year stern trawler SCH 123 ZEELand from Jaczon in Scheveningen will undergo a major upgrade. the vessel which was built in 1989 at the shipyard YVC has already been refitted once in the year 2000. this year the owners decided to completely upgrade/refit the vessel.

the main reason of the upgrade is that the vessel is currently fitted with a freezing installation which has Freon 22 as refrigerant. during conversion a nH3 / Co2 installation will be fitted.

Vuyk Engineering rotterdam executed the main part of the engineering in close cooperation with Jaczon and the main subcontractors.

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the upgrade comprises:

the renewal of the entire freezing installation, which will be located in a separated gastight space to –minimize safety risks.the addition of an extra generator set in the engine room, for extra power supply to the refrigerating –machinery.Upgrade of the engine room equipment, all ship systems and an extension of the switchboard room. after –the conversion the vessel will be capable of working in tropical climates.renewal of a large part of the accommodation, including the mess room and other accommodation –spaces.rearrangement of the aft deck, including upgrades of the deck crane on the trawl gallows and power –block crane.rearrangement of the rSW system and fish tank configuration. –rearrangement of the tank configuration. Several ballast tanks are subdivided and the ballast system is –prepared for the future installation of a water ballast treatment system.

at this moment the final yard offers are being evaluated. after final selection the vessel will depart from its home port in Scheveningen and arrive at the shipyard at the beginning of october 2011.

in September 2010 the dutch ‘Loodswezen’ ordered three so-called Pilot Station Vessels (PSV’s) from the dutch Shipyard Barkmeijer Stroobos. these PSV’s will replace the currently used station vessels of the ‘mirfak’ class, built by Vuyk Shipyards, which served for more that 30 years. in this project Vuyk Engineering rotterdam acted as a consultant for the dutch pilot association (Loodswezen). the most important issue was to translate all requirements and demands as formulated by Loodswezen to one consistent basic design for the shipyard for their detailed design and production. items like habitability, ship motions, safety and efficiency of pilot transfer were important in this process. our consultant acted as intermediary between Loodswezen and Barkmeijer Stroobos up to the moment the building contract was signed.

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dUtCH ‘LoodSWEZEn’

these large pilot vessels will serve as a platform at sea for the pilotage of sea-going vessels in the rotterdam and Scheldt areas. after piloting a sea-going vessel the pilots return to the station vessel to wait for the next assignment. the PSV’s will also be able to support other pilot vessels. the vessels are equipped with a diesel electric system, which reduces the environmentally harmful emissions. most of the time, the PSV operates near the pilot station, close to incoming and outgoing marine traffic. in emergency situations, e.g. preventing a collision, the PSV needs to accelerate quickly. the first PSV is expected in the fall of 2012.

three new Pilot Station Vessels for

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VUYK EnginEEring rottErdam B.V.P.o. Box 12900 aa Capelle a/d iJsselthe netherlands

For further information please see our website. on our website, this Vuyk today is available for download and can be ordered as a hardcopy.

Some product sheets have been added with more details of the projects than mentioned in this issue.

Phone:Fax:E-mail:Website:twitter:

+ 31 10 760 16 00+ 31 10 760 16 99

vuyk@vuykrotterdam.comwww.vuykrotterdam.com

@VuykEngineering

recently delivered rainBoW Warrior for which VEr acted as project coordinator and executed the building supervision.