TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH

TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH TÀI LIỆU về cẩu XUỒNG và PHAO cứu SINH

Centre for Mechanical and Maritime Structures Van Mourik Broekmanweg 6 P.O Box 49

An Overview of Life Saving Appliances and Rationale of Regulations

Date October 20, 2004 Author(s) Wolf M.J., Vredeveldt A.W

Copy no

No of copies Number of pages 42 Number of appendices Customer Nienhuis Beheer & Maritieme Consultancy BV Projectname LSA DGG Doelregelgeving

Projectnumber 006.48268

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© 2004 TNO

Contents

1 Introduction 3

2 Overview of Life Saving Appliances onboard merchant vessels 4

2.1 Free fall lifeboat 4

2.1.1 General description 4

2.1.2 Procedures for use 5

2.1.3 Subsystems 6

2.2 Davit launched lifeboat 13

2.2.1 General description 13

2.2.2 Procedures for use 14

2.2.3 Subsystems 15

2.3 Raft 20

2.3.1 General description 20

2.3.2 Procedures for use 22

2.3.3 Subsystems 24

2.4 Man Overboard Boat (MOB)/ Rescue boat 27

2.4.1 General description 27

2.4.2 Procedures for use 28

2.4.3 Subsystems 29

3 Rules and Regulations 31

3.1 Introduction 31

3.2 Circumstances 34

3.3 Human aspects 35

3.4 Mechanical aspects 37

4 Discussion and conclusions 39

5 References 40

6 Acknowledgement 41

7 Approval 42

1 Introduction

V&W has the intention to explore the possibilities of goal based regulations in the shipping industry The area of life saving appliances onboard sea-going vessels has been chosen as an example case

This report gives an overview of available Life Saving Appliances (LSA) used onboard Dutch merchant ships and makes the objectives, implied in the SOLAS regulations explicit with respect to aspects such as embarkation, launching, release etc

The LSA’s which are described are the free fall life boat, the davit launched life boat, the inflatable raft and the Man Overboard Boat (MOB) For each system, the procedure how to use it is described as well as some of the important subsystems like the davit system

The Dutch fleet comprises approximately 1376 [11] ships, of which about 65% ships have a length less than 85 m Those ships can fulfil LSA requirements through inflatable rafts A rescue boat is obligatory All other ships need to have a lifeboat onboard, this can be a free fall lifeboat or a davit launched lifeboat As a backup they also need to have rafts onboard Ships build after 1986 must have totally enclosed lifeboats, ships before 1986 may also have open lifeboats

The outline for this report is as follows In chapter 2 the LSA’s are described, providing

a general understanding to the readers of the systems Chapter 3 presents the results of

a study of the SOLAS rules with respect to LSA’s, including some comments with respect to the rationale behind the rules In chapter 4, some discussion and conclusions are given

Free fall lifeboats are located at the stern of a ship Examples of free fall lifeboats used

on merchant ships are shown in Figure 2.1 and Figure 2.2

Figure 2.1Free fall lifeboat (make: Norsafe [1])

Figure 2.2 Free fall lifeboat at aft of ship (make: Norsafe)

The launching of a free fall lifeboat is entirely based on gravity without the use of any wire falls After the release hook is opened, the boat starts to slide along the skid, has a short free fall and enters the water Due to its forward motion, the boat sails

immediately away from the ship and reaches a safe distance within seconds from the moment of release

The lifeboat is boarded through an aft door with access to the seats on either side of the central aisle The seats can be front facing as well as rear facing Typical rear facing seating arrangement is shown in Figure 2.3 and Figure 2.4 Passengers are strapped into their seats with safety belts The average capacity of free fall lifeboats varies between 8 and 90 people

Figure 2.3 Typical seating arrangement in a free fall lifeboat (make Norsafe)

Figure 2.4 Overview of seating arrangement in a free fall lifeboat (make Norsafe)

Launching The free fall lifeboat (Figure 2.5) is stowed in skid (1), at the stern of the ship This position at the ship ensures that even under a list of 200 and a trim up to 100, the release

angle is still sufficient for a safe launch If the lifeboat is launched from the sideboard, the release angle can become too small From model experiments it is known that with a too small launching angle, the lifeboat can bounce back from the water like a floater The lifeboat slides on rollers (2), which are connected to the skid, the launching ramp for the lifeboat In some designs, the lifeboat slides on Teflon plates, which are vulnerable for wear

After embarkation of the passengers, the lifeboat can be launched by opening the release hook(s) This is controlled from inside the lifeboat By opening a valve, a hydraulic circuit is opened and by pumping, pressure can be build up The pressure is used to operate the release mechanism Two persons are required for this operation, one

to open the valve, the other for building up the pressure In Figure 2.9 and Figure 2.10 two types of release hooks are shown, which are explained in section 2.1.3

Embarkation Embarkation into the lifeboat is via an aft door Passengers take their seat and strap themselves in Depending on the type of lifeboat, it can be necessary to strap the head

as well Because persons are strapped in, it is not possible to let them wear a lifejacket, unless it is an inflatable lifejacket The lifejacket can be stowed in the lifeboat or taken from the ship and placed under the seat or on the knees during the launch It is not allowed to take any other loose objects in the boat Objects like a hammer or screwdriver can seriously harm the passengers during launch

Figure 2.5 Free fall davit with A-frame (make Ned-Deck Marine [2])

Figure 2.6 Free fall davit with A-frame, retrieval (make Ned-Deck Marine)

Figure 2.8 Free fall lifeboat in skid; Release hook indicated in circle (make Fassmer [3])

Figure 2.9 Free fall lifeboat release hook (make fassmer) a) connection to fixed structure; b) release hook

in stowed position; c) release hook in stowed position; d) close up of release hook prior to release

From inside the lifeboat, a cam (1, Figure 2.9 d)) can be turned by hydraulic pressure

The hook (2) is free to turn round its hinge (4) and the shackle (3), which is connected

to the fixed frame, is released The boat is able to slide down the skid

Type II The second type is the so called twist lock system shown in Figure 2.10 It is positioned

in the centre at the aft of the lifeboat

1

4

c)

Figure 2.10 Twist lock; free fall lifeboat release mechanism (make Verhoeff [4]) a)twist lock hook; b)

lifeboat in stowed position; c) sketch of working principle

In stowed position, the twist lock prevents the lifeboat from sliding The twist lock can

be turned 900 from inside the lifeboat by hydraulic pressure In this new position, the lifeboat is released and can slide along the skid

Type III For the third type an hydraulic pump lifts the aft of the boat until a hook disengages the securing bar on the davit The boat is then free to fall The company Norsafe uses this type of release mechanism

Retrieval

The free fall davit system has an hydraulic driven A-frame construction and an hydraulic driven winch In Figure 2.6 the position of the A-frame is shown while in stowed position and while in lifting position The retrieval of the lifeboat is done by falls, which need to be connected to the off-load hooks at the lifeboat An example of the hook is shown in Figure 2.11 The design of the retrieval construction can e.g be a 3-point sling with or without a spreader Figure 2.12 shows the lifeboat retrieval with the 3-point sling with a spreader

Figure 2.11 Off-load retrieval hook

Figure 2.12 Lifeboat while in falls for retrieval

Retrieval of lifeboats without an A-frame is done with an additional crane, which can also be used for the rafts and possible stores

Supplementary safety options

Free fall lifeboats are required on tankers with toxic or flammable cargo In an emergency situation, it can be possible that the lifeboat is launched in toxic air or in a fire For these reasons most free fall lifeboats can be sealed hermetically and are equipped with air bottles to provide oxygen A spray system on the outside of the lifeboat ensures cooling of the boat while sailing in a fire (see Figure 2.13)

Figure 2.13 Watercooling system

Float free arrangement

Some of the free fall lifeboat are automatically released when the ship sinks A schematic picture is shown in Figure 2.14 This is not obligatory

Figure 2.14 Float free of lifeboat

Most free fall lifeboats are fitted with arrangements which prevent the boat from a

‘spontaneous’ free fall in heavy weather If these fittings are not in place, vertical accelerations of the ship may lift the boat from its release hook This can happen for a lifeboat with e.g the twist-lock, which is not secured in vertical direction

When using the safety arrangement for heavy weather, the lifeboat is no longer float free

An example of such a safety device is shown in Figure 2.15 A flat plate on each side of the lifeboat can be positioned above the bumper of the lifeboat It prevents movement in vertical direction The device must be removed before launching the boat

Figure 2.15 Lashing of free fall lifeboat; a) lashing seen from the aft towards the bow; b) close-up of lashing

2.2 Davit launched lifeboat

Two types of lifeboats are used onboard Dutch merchant vessels: open lifeboats (on vessels built before 1986) and totally enclosed lifeboats, which are obligatory for vessels built after 1986

The davit launched lifeboat is lowered by means of a davit system and wires There are several davit systems available, of which the most common ones are described in this section 2.2.3

An example of a closed davit launched lifeboat is shown in Figure 2.16, an open lifeboat in Figure 2.17

Figure 2.16 Davit launched totally enclosed lifeboat (make Fassmer)

Figure 2.17 Open lifeboat in Davit (make survival craft [5])

The number of complement of a totally enclosed lifeboat can go up to 150 persons, which are used onboard passenger vessels A typical seating arrangement is shown in Figure 2.18 Passengers can use the safety belts during launching and in heavy sea

Figure 2.18 Typical seating arrangement Totally enclosed lifeboat (make Norsafe)

The (open) lifeboat is connected to a davit system by means of hooks, falls and sheaves The purpose of the davit system is to swing out the boat from the inboard position to a point outboard the ship’s side from which the boat may be lowered The davit system is

also used to hoist the lifeboat, which is controlled by means of the falls and an electrical winch

The procedure for lowering and hoisting the lifeboat can be explained with the help of

Figure 2.19 and Figure 2.20

The single pivot davit system comprises a fixed frame (1), which is rigidly connected to the ship and two moveable main arms Each main arm (2) of the davit is connected to a fixed frame, by means of a hinge (3) Falls (4) lead from a drum type winch (5) via sheaves (6) on the fixed frame and main arms to the hoisting hooks (7) The winch is connected to the deck The lifeboat is lowered by means of gravity, independent from a power supply

The procedure for using the lifeboat starts with rigging and securing the painter line This line is connected to the bow of the lifeboat and prevents the lifeboat from turning away from the ship when waterborne The sea-fastenings must be removed

The lowering starts when the winch brake (8) is released by the operator, either from the deck or from within the lifeboat by remote control The lowering speed is controlled

by a centrifugal brake in the winch

At the moment the brake is released, the davit main arm will swing out due to gravitational forces The centre of gravity of the lifeboat and the davit is far from the rotation hinge, ensuring the lifeboat can be lowered up to at least 200 list

The boat should be lowered up to the embarkation deck At that point, the tricing and bowsing gears must be installed, which minimise the movement of the lifeboat during the embarkation

After removing the tricing and bowsing gears, the brake is released again and the boat will lower until it reaches the water level The launching can be controlled by using the brake In the water, the on-load release hooks can be opened simultaneously by pulling

a lever inside the lifeboat This lever can only be used if the hydrostatic release unit in the bottom of the lifeboat has been activated by the water If the hydrostatic release unit does not work, the hooks can still be opened by removing a safety pin, which is located inside the lifeboat close to the release lever The last action is to release the painter line, which often can be done from inside the lifeboat

Retrieval The lifeboat must be manoeuvred underneath the davit First the painter line must be connected The second step is to ‘catch’ the heavy pulley block with the hook The hook must than be connected to the ship and correctly secured Inside the lifeboat, the release lever must be in ‘locked’ position and the safety pin must be replaced The boat can now be hoisted just clear of the water It should than be checked if the hydrostatic release unit is in safe position and the automatic release hook must be checked again if correctly closed If all is safe, the boat can be hoisted to embarkation level The people onboard can disembark and the boat can be hoisted up to stowage position Most davits are equipped with safety stops, which ensures that the winch will automatically stop if the boat is in its final position

Subsystems described in this section are the lifeboat, the davit system and the release hook

The lifeboat

Most lifeboats are constructed of glass reinforced polyester, some of aluminium Typical weight of the boat with equipment (without persons) varies between 3000 kg for a 19 persons boat up to 6000 kg for a 150 persons boat

Davits

Single pivot davit (Figure 2.19 and Figure 2.20) This davit type is already described in detail in 2.2.2

Figure 2.19 Single pivot davit (make Ned-Deck Marine)

Figure 2.20 Single pivot davit (make Ned-Deck Marine)

Figure 2.21 Rollertrack davit (make Davit International [6])

Release hooks

All davit launched lifeboats are equipped with on-load release hooks The procedure for the use of the hook is taken from the operation manual of the camsafe release hook [9] Although each hook has its own features, the working principle for each hook is basically the same

There is dual release protection The release handle is secured with a locking pin The release handle is also locked by the hydrostatic release mechanism.

Figure 2.22

1 2

2 Preparation for release of hooks

When the boat is water borne, the hydrostatic valve operates to unlock the release handle

The release mechanism can be made active by removing the locking pin The pin is removed by rotating the pin and pull out

The hook remains locked in place by the moment “M” The cam is also still locking the hook, as shown

on Figure 2.23

Figure 2.23

3 Unlocking the hooks When the locking pin is removed, the hooks are ready to be released This is done by pulling the release handle upwards and then backwards until the cam is in contact with the hook as shown in Figure 2.24 The hook is now unlocked, but kept in place by moment M

Figure 2.24

Fig.3

4 Releasing the hooks

To release the hooks, move release handle to fully open position as shown on Figure 2.25 The cam presses the hook out, and the moment M will turn to the opposite direction and the hook will then release the boat

Figure 2.25

5 AFTER RELEASE When the boat is fully released the hook will turn back to position to be locked because of its own weight Move release handle back to locked position The hook locked again

Figure 2.26

Brake system

The winch system has a centrifugal brake inside the winch and an external brake on the winch The centrifugal brake controls the speed while lowering, the external brake is used to stop the lifeboat from descent The external brake can be operated from the deck

or from inside the lifeboat with a remote control system Figure 2.27 a) and b) show the

remote control system

Figure 2.27 Winch brake system; a) overview of a davit with remote brake control wires shown; b) close up

of winch with brake lever

The hitch free, non-rotating wire (1), is used for the remote control from inside the lifeboat This wire runs via several pulleys and is reeled at an additional drum on the winch drum Before entering the additional drum the wire runs via the pulley (5) which

is connected to the lever (4) of the winch brake By pulling the wire (1) from inside the lifeboat, the brake lever is lifted and the boat starts to lower The additional drum runs

at the same rotational speed as the winch drum This ensures that during the whole lowering process, the brake lever is kept lifted

A weight at the end of the brake lever makes sure that the brake is blocked if the wire is released

2.3 Raft

Two types of rafts are used onboard merchant vessels For ships with the boarding deck more than 4.5 m above the waterline in the lightest sea going condition, davit launched liferafts must be used If the boarding deck is less than 4.5 m above the waterline, throw overboard rafts may be used which are boarded via a rope ladder

Throw overboard raft

The container, in which the liferaft is packed, is thrown overboard The maximum weight of the container may not exceed 185 kg By pulling a rope, the container opens and the raft is inflated to its full size The rafts can be boarded either directly from the ship via e.g a rope ladder or from the water Figure 2.28 shows the procedure for the use of a throw overboard raft

Figure 2.28 Throw over board raft (make Viking [7])

Davit launched raft

The container of the davit launched liferaft is hooked up to a davit and while free hanging outside the ship, the container is opened by pulling a rope and the raft inflates The raft can be boarded directly from the ship while still in the davit After boarding, the raft is lowered to the water and released The total procedure is shown in Figure 2.29 and described in the next section