Feature 2
ability to carry out safe close-proximity
transfer in high sea states. In a nutshell,
the problem is, of course, that there are
no existing types of high-speed ships
that can achieve these objectives, or
for that matter, even meet parts of the
requirement.
Speaking to Warship Technology in
early December, John Vonli, president
of Umoe Mandal (USA) Inc, said Umoe
Mandal’s T-Craft, which has been
model testing of umoe mandal’s T-Craft concept. selected for a full Phase 2 award by the
ONR, is a new ship concept specifically
designed by the company to meet the
water mode, and transforms to a fully to ‘out-of-water’ mode; designing a requirements defined by the T-Craft’s
amphibious mode for final delivery of the variable/retractable skirt geometry; three modes of operation - long range -
payload. integrating active ride control systems good sea-keeping; high-speed - shallow
Designing and building a vessel capable into the vessel concept; and last, but by draught; and amphibious.
of meeting the T-Craft brief will be very no means least, cargo transfer from the ‘The Umoe Mandal T-Craft concept is
exacting, and the T-Craft design will seabase to the T-Craft, in open water. a Surface Effect Ship (SES)/Air Cushion
need to exceed current capability in a Other obvious challenges include weight Vehicle (ACV) hybrid,’ Mr Vonli
number of respects. Some of the most control, system/subsystem reliability, explained, noting that Umoe Mandal has
obvious major challenges to be addressed the variable/retractable skirt geometry, utilised the proven, all-composite Surface
include the ability to deploy, unloaded, and the need to use high strength, Effect Ship (SES) concept from the Royal
over long distances, in high sea states; lightweight, high load-bearing, fatigue- Norwegian Navy’s Skjold class combat
accommodating significantly higher and wear-resistant innovative marine craft to meet the requirements of the first
payloads (four to 10 times) than those composites. Another is the development two operating modes.
transported by current generation landing of mechanisms to transition from Surface ‘For the amphibious operations, the
craft; having a loaded, un-refuelled range Effect Ship (SES) to Air Cushion Vehicle craft will automatically convert to an
of in excess of 500nm at 40knots; the (ACV) deployment whilst maintaining amphibious air cushion vehicle - or
ability to ‘transform’ and traverse sand cushion sealing efficiency. large hovercraft - by lowering side skirts
bars and mud flats; and combining a fully Complementary systems that will outside the rigid SES hulls,’ he explained,
amphibious landing capability. need to be developed and successfully noting that the Umoe Mandal T-Craft
Some of the many technical challenges integrated within the T-Craft platform concept also utilises a proprietary system
to be overcome to enable the T-Craft to include novel rapid, automated roll-on developed by the company for loading
do all of the above include transition roll-off (ro-ro) connector systems which cargo in severe sea states.
of propulsion systems from ‘in-water’ are high sea-state tolerant, plus the Alion Science and Technology, the
second company to have been selected
for the two-year Phase 2 effort, has also
umoe mandal’s T-Craft proposal is derived from the Skjold class fast patrol boats it built for
selected a SES as the basis of its design for
the royal norwegian navy.
the T-Craft, but as project manager Mark
Redmond explained: ‘The T-Craft can’t
just be a SES,’ and that Alion and its team
had conducted numerous trade-off studies
of what he called ‘multiple ship concepts’.
‘The SES is a good platform for parts of
the T-Craft requirement, but it will need to
go fully air cushioned to be amphibious,’
said Redmond. He declined to be specific,
but said that, like the Umoe Mandal
design, the Alion craft would also deploy
retractable side hulls when required
to operate in amphibious mode. The
propulsion machinery for the Alion craft
is believed to make use of gas turbines and
waterjets. WT
Warship Technology January 2008 15
WT Jan - p14+15+16.indd 15 08/01/2008 16:45:53
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