Heavy Lift
Transport System
(Decision Support and
Voyage Reporting System)
Introduction
Heavy lift transportation
over sea has developed over the years. The
Heavy Lift Vessels have become increasingly
large, their cargoes expensive, complex and
delicate.
The apex has been the
largest ever dry transport: Dockwise BV’s
Blue Marlin with the BP Thunder Horse
production platform (60.000 tons weight)
Therefore the preparations
for sea-going tows are thorough: engineering
studies (motion analysis) and sea fastening
calculations result in complex and expensive
sea fastening constructions and ‘limiting
sea states’ during the voyage.
Scheduling, weather delays and potential
damage can cause large (financial) risks for
Operators, Clients and Insurers.
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Regulations and Guidelines
Local and International Maritime Laws
and Regulations for safe transportation are often
supplemented by Industry Standards (‘LOC Guidelines
for Barge Transportation’, ‘Noble Denton Guidelines
for Marine Transportation’, Client Specific
Guidelines, etc.) that specify the criteria for
design, sea fastening, vessel/barge motions and sea
states.
The vessels and cargoes will often
also have their own specific limitations and
restrictions on maximum allowable accelerations
(=forces) and vessel motions.
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Reality
Again: Heavy lift transportation has
developed over the years. As a result of thorough
preparations, the fast majority of transports arrive
safely at their destination.
Sufficient safety margins in the
engineering and preparations, improved weather
forecasting / weather routing capabilities ensure
safe transportation in most cases.
The calculations and preparations are
verified by Warranty Surveyors and other Third Party
experts.
Once the voyage preparations are
completed, the Master of the heavy lift vessel will
be guided during the
transport
by good seamanship and the limits that are defined
in the Transportation Manuals:
Maximum
allowable sea states (Significant Wave Heights)
during the voyage
Maximum
allowable forces on the cargoes, usually
expressed in Roll/Pitch angles
At sea
the Master of the Heavy Lift Vessel is on his own
again.
He will receive weather/wave height
forecasts and routing advice for guidance.
It is however well known that on
board it is virtually impossible to observe the
correct wave heights. 5 Captains and 10 Warranty
Surveyors on the bridge of a vessel will give you 15
different answers on what the actual wave height is.
The actual Roll/Pitch angles of the
tow are visually observed from the tug, and then
again only during daylight. At night the motions of
the tow are often ‘in the dark’.
Since the start of seagoing tows
nothing has really changed over the last decades!
MaxControl
and
Siri
Marine have developed a Tow Monitoring System that
really works!!
