specific source. FDEuses a minimum of six satellites to detect and exclude a possible faulty satellite from the
navigation solution to ensure that the navigation function remains uninterrupted.
The availability of RAIM and FDE might be slightly lower for mid-latitude operations and slightly higher for
equatorial and high-latitude regions because of the nature of the orbits. The availability of RAIM and FDE can
be enhanced by using satellites from multiple GNSS constellations or using SBAS satellites as additional
ranging sources.
8.16 Heave
Boreas can provide vertical heave position at four different points on a ship. The Boreas heave filter is always
on and fully automatic. After power on, Boreas requires approximately 5 minutes for its heave filter to converge
upon an accurate solution. Heave works without a GNSS fix, however best heave performance is achieved
when Boreas has a GNSS fix.
By default Boreas provides heave from the point at which the Boreas unit is mounted, however it can provide
heave at four different offset points on the ship. To configure Heave, use the 9.1.3.8 Reference Point Offsets
page in the web UI or use the 9.2 Using Boreas Manager.
8.17 Environmental Exposure
Whilst Boreas is environmentally protected, there are limits to this protection that must be observed to avoid
damaging the device.
Boreas is only IP67-protected when its connectors are mated (or sealed with the blanking caps) and two IP67
GNSS antennas are attached to it (or the antenna ports are sealed). If any of these connections are not
tightened to the recommended torque, the unit will not achieve its rated protection.
Spanners or tools should never be used to tighten the connectors. Use your fingers to firmly tighten the
connectors. The Boreas seals the top of the enclosure to the base using screws and an o-ring. This o-ring is not
field serviceable, and attempting to open the housing will invalidate the calibration.
8.17.1 Temperature
Boreas should not be subjected to temperatures outside of its operating range. Subjecting Boreas to
temperatures outside of the operating range can affect the factory sensor calibration, potentially causing a
permanent reduction in performance or premature failure. For information about the operating temperature
range, see 6.2 Hardware Specifications.
8.17.2 Water
Boreas complies with IP67 standard, which means that it can be submersed in water to a depth of up to 1 m
deep for a maximum of 30 minutes. Submersion to depths beyond 1 metre can cause water entry and
destruction of the internal electronics, and the sealing is not designed for prolonged or repetitive immersion. Do
not direct streams of water directly at the unit even at low pressure. For cleaning the unit, ensure that no
pressure is used.
Note: Connectors must be installed or blanking caps must be used if the unit is likely to be exposed to
water.
8.17.3 Salt
The Boreas housing is made from hard-anodized marine-grade aluminium and stainless fittings to provide good
corrosion resistance, however cannot tolerate extended periods of time in salt water environments. After any
v1.2 Page 46 11 Oct 2022
Boreas Reference Manual • Using Boreas
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