28 July 2005
Brows should be of sufficient length so that the slope will not exceed 1.5 horizontal
to 1.0 vertical at the worst condition.
Widths should be 36-in (914 mm) minimum (clear) passage for one-way traffic and
48-in (1220 mm) minimum (clear) passage for two-way traffic. Provide a 60-in (150
mm) minimum (clear) passage for two-way traffic when personnel carry small loads.
Use fiberglass, aluminum, steel, timber, or a combination of these materials.
Aluminum and fiberglass are generally preferred for the low weight to strength ratio
and corrosion protection.
Design the brow structure for a uniform live load of 75 lbs./ft2 (366 kg/m2) and a
concentrated live load of 200 lbs (90.7 kg) applied anywhere. A reduction in the live
load to 50 lbs./ft2 (244 kg/m2) may be permissible where the brow is to be used in
conjunction with a landing float. For calculation of reaction to the landing float, the
live load can further be reduced to 25 lbs./ft2 (122 kg/m2.)
Design handrails to resist 50 lbs per lineal foot (75.6 kg per lineal meter,) applied in
any direction at the top. Design handrails to resist a single concentrated load of 200
lbs (90.7 kg,) applied at any direction at any point along the top. It is assumed that
the uniform load and the concentrated load do not act concurrently. The handrail
may be designed to serve as the top chord of a truss when sufficiently braced.
Provide safety devices to keep the brow from rolling off the platform deck and to
prevent movement of the platform while in use. Clip safety chains into position for
personnel safety. Large tidal variations are a problem because these may cause the
brow to roll off the platform. A similar situation exists when high winds, currents, and
extreme tides pull a ship away from the pier.
Brow platforms are used when a brow from ship deck to pier deck is not practical, or
presents an obstruction. Examples are portal crane trackage along repair berths,
large tidal variations, and great height from deck to pier. Aircraft carriers (CVs and
CVNs) usually use one brow forward and two aft. These brows require platforms 20
ft (6.1 m) or higher. This platform is basically a truncated tower, with typical