Hovertrans Inc. was formed by the original managers of Mackace (Mackley Air
Cushion Equipment) who have extensive experience designing, constructing and
operating heavy lift hoverbarges and hover drilling platforms throughout the
World.
No other company has the same level of experience or knowledge in the
development of hover barges.
Air Cushion Principles
Air Cushion Principles began with Sir Christopher Cockerell in the 1950's. He
invented the method of a vehicle riding on a bubble of air - the hovercraft. The
advantages seemed huge as this would reduce the skin friction and sea transport
would become more efficient.
However, the real use for the idea, moving heavy loads over difficult terrain,
such as swamps, was overlooked by the excitement of the Government funding to
develop high-speed hovercraft. It was not until the early 1970's that the
technology was used for moving a modular marine barge with a dragline on board
for use over soft reclaimed land. The technology is somewhat different, as
high-speed hovercraft has traditionally been constructed using aircraft
technology.
The initial concept of the air cushion barge has always been to provide a low -
tech amphibious solution for accessing construction sites using typical
equipment found in this area, such as diesel engines, ventilating fans, winches
and marine equipment. The air cushion vehicle will displace the same amount of
water when on Hover or floating as a normal vessel. It will continue to act as a
displacement vessel until it reaches a certain speed whilst hovering and at this
point it will lift out (over hump speed) and skim on top of the water. The power
to do this is enormous as the power v.'s drag curve, once above 6-7 knots, is
exponential.
The load to move a 200-ton payload ACV barge at 5 knots would be 4 tons but at
15 knots it increases to 36 tons and quickly continues to increase. The skirt
and air distribution design on the high-speed craft again is more complex as
they have to cope with the air cushion being washed out by a wave. The slow
speed and large mono chamber of the hover barge actually helps reduce the effect
of wave action.
Why hoverbarges?
The initial concept of the hoverbarge has always been to
provide a low - tech amphibious solution for accessing construction sites using
typical equipment found in this area, such as diesel engines, ventilating fans,
winches and marine equipment. The air cushion vehicle (ACV) will displace the
same amount of water when on Hover or floating as a normal vessel. It will
continue to act as a displacement vessel until it reaches a certain speed whilst
hovering and at this point it will lift out (over hump speed) and skim on top of
the water. The power to do this is enormous as the power v.'s drag curve, once
above 6-7 knots, is exponential.
The load to move a 200-ton payload hoverbarge at 5 knots would be 4 tons but at
15 knots it increases to 36 tons and quickly continues to increase. The skirt
and air distribution design on the high-speed craft again is more complex as
they have to cope with the air cushion being washed out by a wave. The slow
speed and large mono chamber of the hoverbarge actually helps reduce the effect
of wave action.
Economic of lifting on hover
The cost per ton hovered or lifted is not a straight-line curve. A
great deal depends on other factors such as the client's vehicle specification,
density of load, climate, and hover height. Generally the larger the unit and
tons hovered, the more efficient the system. Most of the cost to hover the barge
depends upon the perimeter length. For example on a single load of 100 tons we
require an area of 1555 sq.ft. For a 130 ton load, an area of 2015 sq. ft is
necessary requiring an increase of 30% in lift but only 19% on the perimeter.
Likewise, the larger hoverbarge becomes more economical. To move from lifting a
1000-ton load to 2000 tons would only require a 38% perimeter increase to double
the load.
