MIL-HDBK-1025/5
Overhead-rail launchers, either monorail or duorail, function
d)
the same way as a straddle vehicle except that they are not mobile. Overhead
rail is pushbutton-operated.
The still-leg derrick has the rotational problem of the jib
e)
crane and also requires greater operator skill, and a tagline crew to control
the craft while in the air. Derricks shall be installed for handling larger
craft.
Straddle-truck boat hoist is limited to the boat size and
f)
straddle clearance, and shall be used in conjunction with a launching well or
parallel piers. The hoist is completely mobile.
Typical Facility.
Figure 28 represents a hoist-launching facility
2.6.5.4
with dry storage.
Launching Ramps
2.6.6
Slope. Slope of the launching ramp ranges between 12 and 15
2.6.6.1
Few trailered boats can be launched with a ramp slope flatter than
percent.
12 percent without submerging wheel hubs of the trailer. Many trailered boats
cannot be launched with hub submergence even on a 15 percent slope. Use
either a trailer-tongue extension or launch the craft with a hoist.
Surface
2.6.6.2
Ramp surface should be paved down to an elevation of 3 ft
a)
(.91 m) below extreme low water to ensure that trailers are not backed over
the lower end. The top should be rounded over on a 20 ft (6.1 m) vertical
curve until it becomes nearly level at about 2 ft (.61 m) above extreme high
water.
The wetted part shall be paved with portland cement concrete.
b)
Approach. Nondirectional traffic circulation shall be provided
2.6.6.3
with sufficient maneuvering space, approximately 50 ft by 50 ft
(15.2 - 15.2 m) adjacent to the top of the ramp.
Bottom. Bottom of the ramp shall end in a level shelf of loose
2.6.6.4
gravel so that a vehicle losing brakes or traction would be stopped before
sliding deeper into the water.
General Features
2.6.6.5
A single-lane ramp shall not be narrower than 15 ft (4.6 m)
a)
and a multiple-lane ramp should not have raised divider strips.
Provide about 40 to 50 ft (12.2 - 15.2 m) maneuvering room
b)
beyond the top of the ramp on a gentle rampward slope of about 1 on 50 for
proper surface drainage.
Provide boarding docks, preferably, on each side of the ramp
c)
and extending out into or along the sides of the basin with a total boarding
length of at least 50 feet along each ramp.
60
Previous Page
