§ 108.801 Navigation bridge visibility.

Each mobile offshore drilling unit which is 100 meters (328 feet) or more in length and contracted for on or after September 7, 1990, must meet the following requirements: (a) The field of vision from the navigation bridge, whether the vessel is in a laden or unladen condition, must be such that: (1) From the conning position, the view of the sea surface is not obscured forward of the bow by more than the lesser of two ship lengths or 500 meters (1,640 feet) from dead ahead to 10 degrees on either side of the vessel. Within this arc of visibility any blind sector caused by cargo, cargo gear, or other permanent obstruction must not exceed 5 degrees. (2) From the conning position, the horizontal field of vision extends over an arc from at least 22.5 degrees abaft the beam on one side of the vessel, through dead ahead, to at least 22.5 degrees abaft the beam on the other side of the vessel. Blind sectors forward of the beam caused by cargo, cargo gear, or other permanent obstruction must not exceed 10 degrees each, nor total more than 20 degrees, including any blind sector within the arc of visibility described in paragraph (a)(1) of this section. (3) From each bridge wing, the field of vision extends over an arc from at least 45 degrees on the opposite bow, through dead ahead, to at least dead astern. (4) From the main steering position, the field of vision extends over and arc from dead ahead to at least 60 degrees on either side of the vessel. (5) From each bridge wing, the respective side of the vessel is visible forward and aft. (b) Windows fitted on the navigation bridge must be arranged so that: (1) Framing between windows is kept to a minimum and is not installed immediately in front of any work station. (2) Front windows are inclined from the vertical plane, top out, at an angle of not less than 10 degrees and not more than 25 degrees. (3) The height of the lower edge of the front windows is limited to prevent any obstruction of the forward view previously described in this section. (4) The height of the upper edge of the front windows allows a forward view of the horizon at the conning position, for a person with a height of eye of 1.8 meters (71 inches), when the vessel is at a forward pitch angle of 20 degrees. (c) Polarized or tinted windows must not be fitted.