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Marine Auxiliary Machinery

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The windlass cablelifter brakes must be able to control the running anchor and cable when the cablelifter is disconnected ... Figure 9.5 shows a typical arrangement. – PowerPoint PPT presentation

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Title: Marine Auxiliary Machinery


1
Marine Auxiliary Machinery
  • Chapter 9 Lesson 3
  • Deck Machinery
  • Anchor Handling

By Professor Zhao Zai Li 05.2006
2
ANCHOR HANDLING (1)
  • The efficient working of the anchor windlass is
    essential to the safety of the ship, An anchor
    windlass can expect to fulfill the following
  • 1. The windlass cablelifter brakes must be able
    to control the running anchor and cable when the
    cablelifter is disconnected from the gearing
    during letting go. Average cable speeds vary
    between 5-7 m/sec during this operation.

3
ANCHOR HANDLING (2)
  • 2. The windlass must be able to heave a certain
    weight of cable at a specified speed.
  • This fullload duty of the windlass varies (it
    may be as high as 70 tonne figures between 20
    and 40 tonne are not unusual) but is commonly
    between 4 and 6 times the weight of one
    anchor,the speed of haul being at least 9 m/min
    and up to 15 m/min.
  • 3. The braking effort obtained at the cable
    lifter must be at least equal to 40 per cent of
    the breaking strength of the cable.

4
ANCHOR HANDLING (3)
  • Most anchor handling equipment incorporates
    warpends for mooring purposes and light line
    Speeds of up to 0.75 to 1.00 m/sec are required.
  • The most conventional types of equipment in use
    are as follows.

5
Mooring windlasses (1)
  • This equipment is self contained and normally one
    prime mover drives two cablelifters and two
    warpends, the latter may not be declutchable and
    if so, rotate when the cablelifters are engaged.
  • There is some variation in detail design of cable
    lifters and in their drives.
  • Figure 9.5 shows a typical arrangement.
  • Due to the low speed of rotation required of the
    cablelifter whilst heaving anchor, (35 rev/min)
    a high gear reduction is needed when the windlass
    is driven by a high speed electric or hydraulic
    motor.

6
Mooring windlasses (2)
  • This is generally obtained by using a high ratio
    worm gear followed by a single step of spur gears
    between the warpend shaft and cablelifters,
    typically as shown in Figure 9.6.
  • Alternatively, multi steps of spur gears are used.

7
Figure 9.5
Part plan of windlass dog-clutch-type lifter
8
Figure 9.6
Typical electrically driven mooing windlass
9
Anchor capstans (1)
  • With this type of equipment the driving machinery
    is situated below deck and the cablelifters are
    mounted horizontally being driven by vertical
    shafts as shown in Figure 9.7. shaft.

Anchor cable andwarping capstan
10
Anchor capstans (2)
  • In this example a capstan barrel is shown mounted
    above the cablelifter (not shown) although with
    larger equipment (above 76 mm dia cable) it is
    usual to have only the cablelifter, the capstan
    barrel being mounted on a separate

11
Winch windlasses
  • This arrangement utilises a forward mooring winch
    to drive a windlass unit thus reducing the number
    of prime movers required.
  • The port and starboard units are normally
    interconnected, both mechanically and for power,
    in order to provide standby drive and to utilise
    the power of both winches on the windlass should
    this be required.

12
Control of windlasses (1)
  • As windlasses are required for intermittent duty
    only, gearing is designed with an adequate margin
    on strength rather than wear.
  • Slipping clutches are commonly fitted between the
    prime mover and gearing to avoid the inertia o f
    the prime mover being transmitted to the
    machinery in the event of shock loading on the
    cable when, for example,the anchor is being
    housed (see Figure 9.8).

13
Figure 9.8
Slipping clutch
14
Control of windlasses (2)
  • Windlasses are normally controlled from a local
    position , the operator manually applying the
    cablelifter brake as required to control the
    speed of the running cable, and whilst heaving
    anchor the to operator is positioned at the
    windlass or at the shipside so that he can see
    the anchor for housing purposes.
  • It is quite feasible, however, to control all
    functions of the windlass from a remote position.

15
Control of windlasses (3)
  • The spring applied cablelifter brakes are
    hydraulically released and to aid the operator,
    the running cable speed and the length paid out
    are indicated at the remote position during
    letting go.
  • The cablelifter can also be engaged from the
    remote position so that the anchor can be veered
    out to the waterline before 1etting go or heaved
    in as required.

16
Control of windlasses (4)
  • The windlass is in the most vulnerable position
    so far as exposure to the elements is concerned
    and maintenance demands should be an absolute
    minimum.
  • Normally primary gearing is enclosed and splash
    lubricated, maintenance being limited to pressure
    grease points for gunmetal sleeve bearings.
  • However, due to the large size of the final of
    bevel or spur reduction gears, and the clutching
    arrangements required, these gears are often of
    the open type and are lubricated with open gear
    compounds.
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