“So we started looking at how we
could deliver a low-displacement,
fuel-economical boat but still have
good seakeeping,” Lundin said.
“LOMOcean, a company in New
Zealand, had a wave-piercing tri-
maran — Earthrace — with fantas-
tic seakeeping capabilities, low drag
and the stability that sort of platform
can offer. So we asked them if we
could do something like that on a
bigger scale. The designer told us
that a bigger ship will scale very
well. In fact, they told us, ‘the bigger
the ship, the better the ride.’”
North Sea Boats, LOMOcean and
the Indonesian Navy tested the tri-
maran design at the Indonesian Hy-
drodynamics Laboratory (IHL) in
Surabaya, then verified their test re-
sults at the Australian Maritime Col-
lege at the University of Tasmania.
“We got extremely good results
with our model in 4-meter wave heights at 40 knots without any problems. We tested other 40-meter, 50-meter
conventional patrol boat designs of similar displacement
for comparison. The traditional hulls having big problems
at 12 knots in the same heavy seas where we were doing
well at 40. So, with the seakeeping qualities of the design
thoroughly tested, in all conditions and in two different
test tanks, we felt confident that we had one of the best
hulls in the world, with a pedigree from one of the best-known naval architects in the world,” Lundin said.
Why a trimaran? The Independence-class variant of
the U.S. Navy’s littoral combat ship (LCS) is a notable
example, but trimaran combatants are uncommon.
There are some real advantages, however.
According to Dr. Lawrence J. Doctors, a professor at
the School of Mechanical and Manufacturing Engineering
at the University of New South Wales in Sydney, and
author of a new book, “Hydrodynamics of High-Performance Marine Vessels,” trimarans offer different
geometric parameters that can be selected in order to
minimize the overall resistance of the craft, provide for
lateral stability and minimize the motions in a seaway.
“The displacement of the two side hulls can be chosen, as well as their offset from the center hull.
Furthermore, their longitudinal position relative to the
center hull, or stagger, can be chosen. Optimal configurations generally are those trimarans with a relatively
great length and with a small percentage of the displacement carried by the two side hulls,” Doctors said.
A trimaran hull arrangement separates the stability
— the ability to return to the upright after being displaced by waves or weather — from the crew comfort
and habitability of a craft.
“The shape below the waterline of a trimaran deter-
mines the stability, which is generally excellent because
of the multihull characteristic, with the outer hulls hav-
ing a large leverage. The shape above the waterline
determines how the boat responds to waves in rolling
and pitching, which is the direct driver of comfort for
those on board,” said Dr. Tony Armstrong of Fastships
Pty. Ltd. in Fremantle, Australia, the company that
designed the LCS USS Independence. “A trimaran is the
only shape that allows the designer to change stability or
comfort levels independently from each other.”
“It is not inappropriate to think of the trimaran con-
figuration as being analogous to a bicycle with training
wheels,” said Dr. Chris B. McKesson, who teaches na-
val architecture at the University of British Columbia
Lighter materials also help.
“Reducing weight means less buoyancy is required,
which contributes to high speeds because there is less
ocean to push aside as we travel. Composite material is
one way to accomplish this weight loss,” McKesson said.
“We found that the Visby-class corvettes, made in
Sweden by Kockums, were made from composite,
which was very strong and lighter than steel or aluminum. So we put together a New Zealand hull with a
Swedish superstructure, inspired by the Visby program,”
he added. “We used commercially available technology
Indonesia’s Klewang class of missile patrol boats will be of a trimaran design,
somewhat similar to the U.S. Navy’s Independence-class littoral combat ships.
Made of composite materials, the boats will provide a fast, stealthy and flexible
asset to the Indonesian navy, which is seeking to improve its defensive and