Feature 7 | ADVANCED HULLFORMS
Adjustable-length trimaran proposed for
high-speed sealift*
A concept for a novel adjustable-length trimaran designed for service as a
high-speed sealift vessel was described at the recent SNAME 2008 annual
conference.
iff erent numerical hydrodynamic
tools were used to assess the
Dperformance of the vessel, and an
extensive model test programme including
powering and seakeeping experiments was
conducted to investigate the utility of the
numerical predictions.
As the authors of the paper explained,
for ship designers the increasing emphasis
on rapid and fl exible support of logistic
missions represents several distinct
technical challenges. Among these, one
of the most difficult is the desire for
significantly higher speeds, and vessels
capable of carrying substantial military
payloads over trans-oceanic distances
without prohibitive increases in ship size,
power and fuel consumption.
Evolving mission needs for logistics
in expeditionary warfare have not yet
converged to a single view, noted the The authors of the SNAME paper envisioned a trimaran in which the three hulls are of
authors of the paper. However, several approximately equal length of nearly equal displacements. A trimaran of this type, with
independent visions of the future, the hulls staggered (instead of directly alongside one another), can achieve substantial
reinforced by recent concept studies and wave resistance advantages compared with other confi gurations.
designs, have included a doubling of transit
speed, from 20-24knots to speeds exceeding
40knots; cargo payloads from several “While designers strive to generate
•
Military payload of 4000short tons
hundred to several thousand tonnes; and concepts that will fulfi ll future logistic needs, (representing approximately the weight
stage lengths varying from about 2500 to including some hullform types that are and stowage area for vehicles of a Stryker
about 6000nm. unprecedented, the hydrodynamic analysis battalion task force)
“Ship length constraints for austere tools that they rely on are under-developed
•
Austere port access: maximum over-all
port operations demand solutions that and not fully validated in these new length 170m; maximum draft 6.5m
diff er markedly from the conventional, operating regimes. The development of
•
At-sea transfer of vehicle cargo
large, sealift ship,” noted the authors of new ship concepts, and new design tools, (nominally through Sea State 4)
the paper. must accordingly advance together.”
Recently, the US Offi ce of Naval Research The SNAME paper summarised the
(ONR) supported concept studies and design and hydrodynamic characterisation
hydrodynamic tool development for High of a vessel to meet these mission
Speed Sealift (HSSL) to austere ports. Th e requirements, and identified a design
design ground rules called for the following candidate, and described details about
major capabilities: the unique challenges that accompany
•
Unrefuelled range: 5000nm at average its unconventional form. Experimental
speed of 43knots measurements and numerical predictions
An adjustable-length trimaran has been
•
Full mobility, including 43knot-speed, used during the design process were
proposed for high-speed sealift. through Sea State 4 introduced and discussed, and calm
Warship Technology October 2008 61
WT_Oct08_p61+64+66+68+70.indd Sec1:61 10/10/08 1:20:26 PM
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