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TABLE OF CONTENTS

1.Introduction: Shiplift system . . . . . . . . . . . . . . . 03

2.Set up of shiplift system . . . . . . . . . . . . . . . . . . . .03

3.Working of shiplift system . . . . . . . . . . . . . . . . . 04

4.Class designation . . . . . . . . . . . . . . . . . . . . . . . . . .10

5.Design principles. . . . . . . . . . . . . . . . . . . . . . . . . . 11

6.Design loads acting. . . . . . . . . . . . . . . . . . . . . . . . 11

6.1 Nominal lifting capacity. . . . . . . . . .11

6.2 Lifting load. . . . . . . . . . . . . . . . . . . . . 11

6.3 Live load. . . . . . . . . . . . . . . . . . . . . . . .12

7.Synchrolift shiplifts and transfer system . . . . . 12

7.1 synchrolift systems. . . . . . . . . . . . . . . 12

7.2 working . . . . . . . . . . . . . . . . . . . . . . . ..12

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7.3 features. . . . . . . . . . . . . . . . . . . . . . . . . . .13

7.4 shipyard applications. . . . . . . . . . . . . . .14

7.5 other applications. . . . . . . . . . . . . . . . . . 14

8.Petrinet model used for simulation . . . . . . . . . . . . . 15

9.Advantages of GSPN . . . . . . . . . . . . . . . . . . . . . . . .. . .16

10. Equipments used in shiplift system . . . . . . . . .17

10.1 winches. . . . . . . . . . . . . . . . .. . . . . . . . . 17

10.2 platform. . . . . . . . . . . . . . . . . . . . . . . . ..17

10.3 trestles. . . . . . . . . . . . . . . . . . . . . . . . . . . .17

10.4 boogies. . . . . . . . . . . . . . . . . . . . . . . . . . .17

10.5 SPPS. . . . . . . . . . . . .. . . . . . . . . . . . . . . . .17

11. Shiplift system in India . . . . . . . . . . . . . . . . . . . .20

a) Goa shipyard. . . . . . . . . . . . . . . . . ..20

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b) INS KADAMBA. . . . . . . . . . . . . . . . .24

12. Other large shiplift systems in world . . . . . . . . 25

13. Advantages of shiplift system . . . . . . . . . . . . . . . 25

14. Disadvantages of shiplift system . . . . . . . . . . . . 25

15. Bibliography . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 26

1. introduction A shiplift is a large elevator platform, which can be lowered into water, have a ship

hauled-in and positioned over the cradle/blocks preset on the platform and then lifted vertically to the yard level, so that the ship can be moved from the platform on to a dry repair berth on land.

Alertnative way to dock a ship without a dry dock , floating dock or pontoon docks Electrically controlled lift platform that lifts ship from water with help of a number of

lift winches. Also occupied with transfer system to transfer ship from platform to workup area

through railings. Electonic sensors keeping track loads on each winch and load distribution and

alignments.

2. setup

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A shiplift consists of a steel lifting, platform, suspended by wire ropes attached to hoist drums, raised and lowered vertically by a series of hoists.

The hoists are distributed in equal numbers on either side of the platform and are located on piers or foundations.

The hoists are driven in a synchronised mode. By synchronising all the hoists, the platform with or without a ship is raised or lowered vertically, uniformly and in a horizontal plane. Finer levelling adjustment is built into the system.

The shiplift is controlled and operated from a control system and operator console. The control system has a number of in-built safety mechanisms in order to prevent incidents that may arise due to overloading or underloading conditions or severe imbalance of the platform due to shipload and a variety of other causes.

The Ship Transfer System is of modular design and construction so that it can be reconfigured to suit varying lengths and beam of Indian Navy ships. The modular system greatly enhances the flexibility and versatility.

In the current program, two sets of these modular cradles are included for dry docking 2 ships; additional sets can be added for each new berth, as and when constructed.

The ships and cradles are transported by a self-driven hydraulic bogy system, both longitudinally and transversely. Only one set of hydraulic bogies is required for the ship movement and transfer operations in the yard. The bogies need not be immersed in seawater.

By interconnecting and grouping the hydraulic bogies, the heavier sections of keel loads can be redistributed more evenly and thus heavier ships lifted.

The Shiplift and Ship Transfer System is designed for a long service life of 50 years and it is capable to dock most ships.Also, is quite suitable for dry docking coastal and medium size cargo vessels.

3. Working

A platform includes main transverse beams (“MTBs”), each supported by at least one hoist. It is determined whether a load on any MTB is different from the load on any other MTB by more than a predetermined amount.

An MTB which has a load different from the load on any other MTB by more than a predetermined amount is selected and then vertically moved with respect to the other MTBs within a predetermined safety limit to transfer load between the selected MTB and the other MTBs while monitoring the loads on each MTB and the position of the selected MTB as vertical movement of the selected MTB proceeds.

The monitored loads and position are compared with the safety limit; and the movement of the selected MTB stopped when either the desired load transfer is completed or the safety limit has been met.

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DIAGRAMMATIC SIDE ELEVATION VIEW OF A SHIPLIFT

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PLAN VIEW OF A SHIPLIFT

In an alternative embodiment , a method for operating a lifting mechanism having a platform and a plurality of irregularly spaced blocking mechanisms to support a load of an item to be lifted on the platform, includes collecting position data on each of the blocking mechanisms with respect to the platform, estimating a mass of the item to be lifted and estimating a longitudinal center of gravity of the item to be lifted.

An estimated loading curve on the platform based on the position of the irregularly spaced blocking mechanisms, the mass and longitudinal center of gravity of the item to be lifted is calculated and the estimated loading curve outputted.

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LOGIC FLOWCHART OF SECOND MODE In an alternative embodiment , a method for operating a lifting mechanism

having a platform, a plurality of hoists to lift the platform and a plurality of blocking mechanisms to support a load of an item to be lifted on the platform, includes collecting position data on each of the blocking mechanisms and reading a load on each hoist.

A load on each blocking mechanism based on the position of each blocking mechanism, the loads on each hoist and a predetermined relationship between a stiffness of the platform and its load is calculated and the

calculated load on each blocking mechanism is outputted.

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LOGIC FLOWCHART OF THIRD MODE In an alternative embodiment , a method for operating a lifting mechanism

having a platform, a plurality of hoists to lift the platform and a plurality of blocking mechanisms to support a load of an item to be lifted on the platform, includes collecting position data on each of the blocking mechanisms and reading a load on each hoist.

An estimated tons per meter loading on the platform based on the load on each hoist, the positioning of each blocking mechanism and a length of the platform is calculated and the estimated tons per meter calculation outputted.

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LOGIC FLOWCHART OF FOURTH MODE

In an alternative embodiment , a method for operating a lifting mechanism includes activating a monitoring operation of the lifting mechanism upon start-up of the lifting mechanism, monitoring certain operating parameters of the lifting mechanism, comparing the operating parameters with predetermined trigger parameters, and logging the operating parameters in the event that any of the trigger parameters are met.

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LOGIC FLOWCHAT OF FIFTH MODE In an alternative embodiment , a method for operating a lifting mechanism,

includes activating a monitoring system upon activation of the lifting mechanism control, selecting a set of system parameters to monitor, and selecting a set of triggering criteria for at least certain of the system parameters.

The system parameters are then monitored until any of the triggering criteria met and then the system parameters are logged to a persistent memory once any of the triggering criteria are met

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LOGIC FLOWCHART OF SIXTH MODE

4.CLASS DESIGNATION

In proof of classification ship lifts obtain the class designation 100 A5 appended the notation "SHIP LIFT" and the nominal lifting capacity NLC in [tons].

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5. DESIGN PRINCIPLES

Under loaded condition the speed of lifting and lowering is restricted to a maximum of 0,5 m per minute. For operations without load, higher speed is permissible.

For the transfer of the ship to the shore the platform has to be locked at the actual transfer side. Ship lifts, which are also used as a working platform (e.g. for ship repairs), have to be mechanically locked on both longitudinal sides for this working condition.

It is assumed, that wind and waves do not create vibrations of the ship lift loaded with a ship, which are not acceptable from safety point of view. Undue movement has to be prevented by guiding devices.

A horizontal alignment of the lifting platform has to be aspired. Inclinations and height differences between adjacent lifting equipment, which are not avoidable during operation have to be limited, that no exceeding of local stress, inadmissible load cycles and disturbances of functions appears.

The deflection of the girders for the travelling rails should not exceed 1/800 of the distance between two supports.

For bolted connections of platform girders preloaded high-tension bolt connections should be chosen

6. DESIGN LOADS acting on shiplift systems

6.1. Nominal lifting capacity (NLC)The nominal lifting capacity NLC is the sum of all loads (weight of ship and weight of the variable parts of the equipment, like carriages, ship bearing blocks,etc.). Usually it is defined in metric tons [t].

6.2. Lifting load for design (MDL)The lifting load for dimensioning MDL is created from the nominal lifting capacity (NLC) by increasing it with a certain factor and will be distributed equally as a line load along the centre line of the platform.

MDL = 10 NLC * ϕ /Leff [kN/m]

NLC = nominal lifting capacity [t]

Leff = effective length of the lifting platform in [m], which serves to

carry the loads of the nominal lifting capacity NLC.

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For Leff the load carrying lengths of the platform ends are to be included in their full length, but not more than half the length between two pairs of lifting devices has to be added on each side.

Φ = load distribution factor

The load distribution factor takes into consideration the unequal distribution of the ship’s weight at the platform axis as well as dynamic effects during docking and can be defined with ϕ= 1,33 for regular cases. The actual size of this factor has to be agreed with GL,taking into account the actual operating conditions.

6.3. Live loadApproachable platform areas not foreseen to be used by live loads have to be calculated using at least the following loads:

An uniformly distributed load of 5 kN/m2, (simultaneous action of this traffic load and the lifting load for design MDL must not be assumed for regular cases)

A singular point load of 10 kN

For designing, the locally more disadvantageous load has to be chosen.Platform areas foreseen to be used for working and transport have to be measured according to the expected maximum live load.

7. SYNCHROLIFT SHIPLIFTS AND TRANFER SYSTEMS

7.1. SYNCHROLIFT SYSTEMSA Syncrolift system is simply a large elevator which raises and lowers vessels in and out of the water for dry-docking ashore.

7.2.WORKING OF SYNCHROLIFT SYSTEMS• To dock a vessel, the platform and cradle are lowered into the water, and

the vessel moved into place over the platform.  • When in position, the Syncrolift Dockmaster raises the platform,

removing the vessel from the water.  • Work on the vessel can then be done in situ, or the vessel transferred

ashore, leaving the Syncrolift available to dock other vessels.  • On completion, the process is reversed.

The modern Syncrolift shiplift is based upon the interaction of several critical features:

• The patented, articulated platform - ensures that shiploads are determinately distributed to respective hoists.

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• The hoists - highly refined machines powered by synchronous electric motors.

• The wire ropes - specially built for high strength and long service life.

• The load cells - continuously monitor and display hoist loadings at the control console.

• The ATLAS Dockmaster control system – simple to operate and provides records and analytical data for the Naval Architect, each of these features has been developed through several iterations to form today’s Syncrolift shiplift. They are continually refined and updated to reflect current state-of-the-art technology, and together constitute the world’s most advanced shiplifting system - providing a faster - safer - more profitable - more versatile method of dry-docking.

7.3. FEATURES OF SYNCHROLIFT SYSTEMS Speed of operation - more ships docked per year. For example - one of our

larger customers performs over 500 drydocking contracts each year using its single shiplift. Typically some of our units are operated 6 - 10 times daily. A Syncrolift minimises the space required for launching ships at the waterside and the transfer system ensures maximum use of the shore work area.

Patented ATLAS Dockmaster® control system - provides the operator with information about the ship that is being lifted. This information enables the operator to analyse the distribution of the load being lifted, and hence to protect the vessel during the docking operation. No other drydocking system does this. It also provides condition monitoring data on the shiplift, which reduces the requirement for routine maintenance and extends component life.

Simpler and faster drydocking procedures - requiring fewer personnel and less man hours to successfully drydock vessels. Typically, drydockings take 25 - 50% less time because of the improved access provided for both labour and materials. A Syncrolift requires no prolonged shutdown period for maintenance.

Long service life -  The Syncrolift shiplift system will not lose capacity in future years due to deterioration of inaccessible underwater parts.

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Syncrolift® shiplifts - self-protecting against electrical and structural overloads and self-protecting against operation beyond permissible up and down limits.

The shiplifts modular design - permits future expansion of the original installation to obtain increased lifting capacity, to provide a dual lifting capacity, to increase platform length or to generally increase the system capabilities.

Drydock alternative - One Syncrolift shiplift with a transfer system can replace several floating dock or drydock facilities and facilitates the use of modern shipbuilding and/or ship repair techniques, such as modular construction.

Minimise space - The Syncrolift design minimises space requirements at the waterfront. When combined with our transfer system, multiple work berths can be created to provide efficient and environmentally safe work areas well away from the water. All work can be safely contained without polluting the waterway.

7.4 Shipyard applications Syncrolifts are custom designed to accommodate a wide range of shipbuilding and ship repair activities according to each customer’s exact lifting requirements. No longer limited to shore side berths, customers can maximize productivity and profitability by putting all their property to constructive use. Hundreds of commercial repair and shipbuilding companies throughout the world depend on the proven reliability of Syncrolift for ship repairs, conversion projects and launching new vessels.

7.5.Other applicationsA heavy-duty lifting device that is safe, reliable, and able to withstand the corrosive conditions of the marine environment. In addition to shipbuilding and ship repair, Syncrolift technology is also used in many other applications...

Ramps for ferriesSyncrolift technology is also used in ramps for passenger ferries and cargo ships. In areas where very high tidefalls make loading and unloading difficult, a Syncrolift ramp with its precise control mechanisms is an ideal solution.

Caisson liftsSyncrolift platforms are used for launching concrete caissons for construction

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of breakwaters, piers, and bridges. With their high unit lift requirements, caisson lifts can be used for a specific project, and then reconfigured and used as a conventional shiplift.

BargeliftsThe Syncrolift concept is also being developed as an alternative to canal locks. Because of its simple design, it is a cheaper alternative to traditional locks and offers several environmental benefits.

8. PETRI NET MODEL FOR SIMULATION

A stochastic Petri net model of the shiplift is used to simulate the shiplift and to evaluate the two alternatives, taking performance, load and customer satisfaction into consideration.

Since there is no special simulation software for this problem, Generalized Stochastic is used as a universal modeling language that allows a quick creation, validation and performance evaluation of models of arbitrary systems. In our case, communicationwith non-simulationists has been necessary, thus a graphical representation and animation of the model was desirable. GSPN provide this graphical representation, that is easier to understand for nonspecialists than e.g. the simulation code written insome programming language.

In GSPN, the system state is modeled by tokens in places (small filled dots inside circles), i.e. the marking. State changes are modeled by transitions (bars). If the state change needs some time, then a timed transition is used (unfilled bar), while for timeless state changes immediate transitions are used (filled bars). When an action occurs, transitions move as many tokens from and to places as indicated by the arcs connecting the places and the transitions.

Figure 1 shows the GSPN model of the shiplift as constructed with the tool TimeNET [2], which enables simulation of the GSPN as well as performance analysis (based on its Markov chain) and qualitative analysis.The transitions arrival_ds and arrival_us model the Poisson arrival process of ships from upstream and downstream, with a mean interarrival time of 29.6 minutes. Ships arrive at

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harbours denoted by the places harbour_ds and harbour_us. The marking of places chamber_us, chamber_ds, chamber_ds2 and chamber_us2 indicate whether the current water level in chamber one/two is adjusted either to the upstream or downstream level. The transitions enter xy test via inhibitor arcs, whether a chamber is in the correct position and also whether the chamber is empty. If there is only one ship to enter a , then this ship enters. If more than one ship is waiting, then the transitions enter xy decide based on specific_c probabilities which are derived from the given distribution of shiplengths (as discussed earlier), how many ships enter the chamber. Note that in the Petri net used here, all ships are uniformly modeled as tokens without any information, so ships cannot be distinguished with respect to their lengths. This approach introduces a certain level of abstraction of the model, which was not easy to understand for the engineers concerned with the reconstruction of the shiplift. Thus we also built a more detailed model with colored Petri nets of the Renew type , where each ship has been modeled as a colored token carrying more detailed information like the length of the ship. The loading of the chambers has also been modelled in detail, that means that it was tested for each ship at the front of a queue, if it still fits into a chamber or not. This detailed model showed nearly the same results, but it is much more complicated and less intuitive. However it gave the engineers more con_dence in Petri net models. It is out of the scope of this paper also to explain the colored Petri net model.

Once ships have entered a chamber, the filling or emptying of the chamber begins. This is modelled by the four deterministic transitions fill_chamber, empty_chamber, fill_chamber2, empty_chamber2,each taking 28.0 minutes. Chambers may only be operated if a token is present in place trigger_chamber/ trigger_chamber2.

Such token is generated when either ships entered the chamber, or waiting ships request a chamber if all two chambers have the wrong water level.After the chamber's operation time, the ships are released into places ds1, ds2, us1 and us2. The marking dependent arc weights ensure that always the proper number of ships is moved

9. Advantages of gspn

GSPN offer a universal formal modeling language making creation and debugging of the model faster and easier than e.g. using C-code.

GSPN have a graphical representation GSPN has a animation at no extra cost

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10. EQUIPMENTS USED IN SHIPLIFT AND TRANSFER SYSTEM

10.1. PLATFORM

Generally wooden deck platform where the blocks are placed to dock the ship.

10.2. WINCHES

Electrically operated , to lift the platform along with ship at a uniform rate of load.

10.3. CONTROL SYSTEM

Located in contol tower of the ship lift system has sensors to sense load on each winch, control lift operations ,check alignment etc.

10.4. TRESTLES

These are the steel blocks on which ship rests.

10.5. BOOGIES/CARRIAGE

They are the part of transfer system which use hydraulic system to lift the trestle and transfer ship along the railings

10.6. SPPS ( SELF PROPELLED POWER STATION)

Provides the hydraulic pressure (for the movement) & lift pressure (for lifting) ,oil suction and ejection provides the hydraulic mechanism involved .

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PLATFORMS

WINCHES

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TRESTLES

BOOGIES/CARRIAGE

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SELF PROPELLED POWER STATION (SPPS)

11. SHIP LIFT SYSTEMS IN INDIA

11.1. GOA SHIPYARD LIMITED

Features of the ship lifting yard

• Docking plan is made for the ship to be lifted by the design section using CAD/CAM .

• Chokes are placed over trestles. Trestles are placed over the lifting platform using boogies .

Ship is placed over the platform which is submerged in water .

• Control room has sensors to checks to see whether the ship is placed over the chokes, if required divers are sent .

• A set of 28 winches are used to lift the ship slowly .

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• Trestles take the load from the chokes .

• Trestles have SWL of 336tons,boogies have SWL of 200tons, the boogies have a bottom jack to rotate the boogies in required direction for shifting of the ship to required bay .

• SPPS (self propelled power station) provides the hydraulic pressure (for the movement) & lift pressure(for lifting), oil suction and ejection provides the hydraulic mechanism involved

• Each winch has a SWL of 375tons .

• 3 steel wires in combination of three are used for better support

• The lifting speed is 5mins/m, and it can go down till a depth of 10.7m .

• Testing of the shiplift system is done with barges of suitable weight usually 1.5 times the swl .

• The chokes are 300mmx1200mm, the chokes are made of top layer of soft wood and bottom layer of hard wood,they are connected by staplers and surrounded by a layer of mild steel, which in turn is welded to the trestle by a flat bar.

• There is a deadman’s switch which switches off the heaving system every 150 secs to prevent any damage to the shiplift system.

• The trestles are placed every 4.8m apart ,they are usually made to coincide with bulkheads or web frames .

• Spring lines are used to align the ship inside the lift bay.

CONTROL TOWER

Systems are connected to the sensors for load check and control of the lift platform Next page shows a demonstrative procedure of control system which is also

dependent on the manufacturer standard operating procedure

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startup

automatic on upon software startup

"power' panel main power switch

"alarms"panel accept button

"winches "panel activate button

platform control panel(up & down or lock & unlock

buttons)

platform control panel stop button or auto stop

winches panel deactivate button

shut down software

shutdown

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SHIP LIFT SYSTEM LAYOUT IN GSL

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11.2. INS KADAMBA

The 10,000t ship lift facility at INS Kadamba naval base features a ship lift and ship transfer system

DIMENSION : 178m x 28m

CAPACITY : 10000 tons

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12. Other large ship lift systems

One of the world's largest shiplift systems is installed in Malaysia Shipyard and Engineering (MSE)'s shipyard at Pasir Gudang, the most prominent industrial town in the State of Johor, with the expertise of Syncrolift Inc, a Rolls-Royce company. The lift capacity is up to 25,000 tons .

The largest shiplift system in the world began operation with the commissioning of the Syncrolift owned by Astilleros Canarios, S.A., at Las Palmas, Canary Islands. With a platform 171.6 meters long by 30 meters wide, the Syncrolift can lift vessels up to 25,000 deadweight tons.

13. ADVANTAGES

Much faster than other docking methods. Provide easier ways of launching avoiding slipways and calculations. Avoids problems related to unavailibility of dry docks or limited dry dock

through ship transfer system.

Avoids risk of dock gate and provides and open and easier accessible work areas

14. DISADVANTAGES Restriction on dimension and displacement. High cost of installation Requires frequent maintenance and safety checks. Operation to be done very carefully and there can chances of ship to roll aside if

seating is incorrect before lift on the blocks. Not suited for ships whose under water area is damaged , hull is cut , very old hulls .

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15. BIBLIOGRAPHY

1. Introduction to naval architecture-I2. WIKIPEDIA3. www.google.com 4. Indian Navy website5. www.abrift.com