COBHAM SAILOR 900, Руководство по установке

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Site preparation
3-10 Chapter 3: Installation 98-150471-A02
Mast length and diameter
The placement of the ADU must ensure a rigid structural connection to the hull or structure
of the ship. Parts of the ship with heavy resonant vibrations are not suitable places for the
ADU. A small platform or short mast shall provide rigid support for the ADU fastening bolts
and a rigid interface to the ship.
If it is necessary to use a tall mast, you must stabilise the mast with bracing. Note that the
design values given below depend on rigid ADU-ship interfaces. The cross-sectional
properties and the corresponding maximum free length give a natural frequency close to
30 Hz. It is recommended to shorten the mast length as much as possible to obtain higher
frequencies. Preferably, mount stays or wires to stabilize the mast further.
The tables in the next sections give some suggested design values for the free mast length.
SAILOR 900 VSAT High Power ADU mast length
The below tables show the minimum dimensions for a SAILOR 900 VSAT High Power ADU
mast with and without stays or wires. Note that the values are only guidelines - always
consider the environment and characteristics of the ship before deciding on the mast
dimensions.
Figure 3-10: Free mast length and bracing for a tall mast
Note
Make sure that there is free space below the drain tube. Read also Condensation
and water intrusion
on page 3-16.
Note
The tables list the values for
steel masts
. For
aluminium masts
, the free mast
length is reduced to 75% of the values for steel.
Note
Bracing and rigid masts can still not prevent vertical vibration if the mast is
attached to a deck plate that is not rigid. Make every effort to mount the mast on
a surface that is well supported by ribs. If this is not possible, provide extra deck
plate propping.
Free mast length (m)
SAILOR900HP.book Page 10 Monday, July 18, 2016 12:44 PM