Talk:Ordnance datum
If Ordnance Datum was 'Mean Sea Level', then low tides should usually be expressed as negative vaues. They are not on tide timetables. So OD must refer to Low Spring Tide level.88.108.30.110 20:11, 12 November 2006 (UTC)
If Ordnance Datum was 'Mean Sea Level', then low tides should usually be expressed as negative vaues. They are not on tide timetables. So OD must refer to Low Spring Tide level.88.108.30.110 20:11, 12 November 2006 (UTC)[reply]