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OSBM Bolt 
NBM OSBM BOLT BASE MAST C NW SIDE (137.248m above Lerwick datum, 2nd order, new 1978).
Location
Grid reference: HU 5118 8818.
Landranger 1: Shetland, Yell, Unst & Fetlar.
Landranger 2: Shetland, Sullom Voe & Whalsay.
Structure: Unknown.
Waypoint: OS2614.
The nearest fundamental bench mark is Duncansby Head, 244.85km to the southwest.
Location
Grid reference: HU 5118 8818.
Landranger 1: Shetland, Yell, Unst & Fetlar.
Landranger 2: Shetland, Sullom Voe & Whalsay.
Structure: Unknown.
Waypoint: OS2614.
The nearest fundamental bench mark is Duncansby Head, 244.85km to the southwest.
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