Sea Tel 6012-12w, Installation Manual

Page: 15 / 130

6012-12W Installation Manual Site Survey
has direct line-of-sight with the satellite without any structures in the beam path through the full 360 degree
ships turn. Wire rope stays, lifelines, small diameter handrails and other accessories may pass through the
beam path in limited numbers; however, even these relatively insignificant shadows can produce measurable
signal loss at these frequencies.
2.3. Mounting Foundation
2.3.1. Mounting on Deck or Deckhouse
While mounting the ADE on a mast is a common solution to elevate the ADE far enough above the
various obstructions which create signal blockages, sometimes the best mounting position is on a
deck or deckhouse top. These installations are inherently stiffer than a mast installation, if for no
other reason than the design of the deck/deckhouse structure is prescribed by the ship’s classification
society. In the deck/deckhouse design rules, the minimum plating and stiffener guidelines are chosen
to preclude high local vibration amplitudes.
Most installations onto a deck or deckhouse structure will require a mounting pedestal to raise the
ADE above the deck for radome hatch access and to allow the full range of elevation (see ADE
mounting considerations above). Some care must be taken to ensure the mounting pedestal is
properly aligned with the stiffeners under the deck plating.
2.3.2. ADE Mounting Considerations
Mounting the radome directly on the deck or platform prevents access to the hatch in the base of the
radome unless an opening is designed into the mounting
surface. If there is no access to the hatch, the only way to
service the antenna is to remove the radome top. Two people
are required to take the top off of the radome without
cracking or losing control of it, but even with two people a gust
of wind may cause them to lose control and the radome top
may be catastrophically damaged (see repair information in
the radome specifications).
If access to the hatch cannot be provided in the mounting
surface, provide a short ADE support pedestal to mount the
ADE on which is tall enough to allow access into the radome
via the hatch.
Ladder rungs must be provided on all mounting stanchions
greater than 3-4 feet tall to allow footing for personnel
safety when entering the hatch of the radome.
The recommended cable passage in the 50, 60 and 66 inch radomes is through the bottom center of
the radome base, down through the ADE support pedestal, through the deck and into the interior of
the ship.
2.3.3. Sizing of the support pedestal
The following should be taken into account when choosing the height of a mounting support stand:
1. The height of the pedestal should be kept as short as possible, taking into account
recommendations given in other Sea Tel Guidelines.
2. The minimum height of the pedestal above a flat deck or platform to allow access into
the radome for maintenance should be 0.6 meters (24 inches).
3. The connection of the ADE mounting plate to the stanchion and the connection of the
pedestal to the ship should be properly braced with triangular gussets (see graphic above).
Care should be taken to align the pedestal gussets to the ship’s stiffeners as much as
possible. Doublers or other reinforcing plates should be considered to distribute the forces
when under-deck stiffeners are inadequate.
4. The diameter of the pedestal stanchion shall not be smaller than 100 millimeters (4
inches). Where the ADE base diameter exceeds 1.5 meters (60 inches), additional
stanchions (quantity greater than 3) should be placed rather than a single large stanchion.
2-2
EAR Controlled - ECCN EAR99