Home' Ausmarine : September 2009 Contents THE ADVANTAGES OF TANK
TESTING FOR A "BETTER BOAT"
"I wish I knew what happened to that lovely woman Jenny
Watsername," muttered my buddy O'Brien.
"Why don't you Google her?"
"I tried that years ago, but her
boyfriend nearly killed me!"
"O'Brien, I am not talking
about googling in the Biblical
sense, nor combobulating in
the sailoring sense, I am
talking about getting on the
internet. You have to get
After my rapid brief
explanation of the internet,
Google, Google earth, and
the fact that websites are
built around generated
content, with a range of
technologies, sites, forums,
message boards, blogs, wikis,
podcasts and microblogging
sites such as Twitter, he really
Rolling his eyes skywards,
he confessed that he would
just keep building boats in his
never ending search for the
The perfect boat, like the
perfect woman, doesn't exist, but
tank testing is a good way of
improving a boat's performance.
The Australian Maritime
College (AMC) in Tasmania
has excellent tank test facilities
under the management of a
very competent Scotsman,
Gregor MacFarlane. As you may
know, the McFarlanes of
Western Scotland produced a
most famous Master Mariner, Peter McFarlane, otherwise known
as Para Handy, around whose adventures an acclaimed TV series
McFarlane's team at AMC has recently been testing a series of
semi-swath vessels for Crusader in Queensland -- in the pursuit of a
"better boat" as opposed to a "perfect boat".
The quest, of course, was to beat the performance of local
boatbuilders of 60-foot sportscruisers and flybridge cruisers, who
unfortunately don't believe in tank testing and have a clientele
whose major wish is to have bigger horsepower in his boat than
the next guy. Sigmund Freud would laugh.
So with a semi-swath hull of 26 tonnes and the same waterline
length as the local brand 60-foot monohulls, the tank testing and
refinements to the hull form ended up with a required horsepower
of just 420 SHP for a comfortable 21 knots.
For the same speed and same displacement the monohulls
require 1000 SHP, and produce a big wave to boot, much to the
delight of those who like surfing in smooth water areas. Some
quick, back-of-the-envelope maths will show you that a trip up to
the reef will cost you 60 percent less from Sydney in the Crusader,
or about $5,000 less, in fuel alone. Of course the lighter and
smaller engines will also be less obtrusive and will not attract the
ire of the new green regulators.
Already the IMO is signalling
vessels will have to have an
"energy index", as an indicator
of its energy efficiency, which
will come to smaller vessels
sooner rather than later.
AMC recently did the testing
on a catamaran pusher tug and
monohull pusher tug with a
15,000DWT sea-going barge, to
see if there was an economic
advantage with one or the other.
The catamaran pusher tug came
in significantly better than the
traditional monohull, and this
has resulted in the Dutch owners
building six of these vessels in
Flushing in Holland for shallow
water operations pushing
15,000DWT seagoing barges in
Europe and Central America.
A 41-metre vessel for the
Bahamas was tested recently at
AMC to see if she did not "squat"
in shallow waters when attaining
a speed of 25 knots. The AMC
tank was drained for two days
to simulate the 300mm
under-keel clearance, and the
tests proved successful.
For those of you who like to
see rough water vessels, the
Orkney Islands vessel 'Pentalina'
was tested in the AMC's wave
tank, using several different bow
shapes. The tests resulted in:-
• reduced pitching motions up to 16 percent,
• reduced heave motions up to 20 percent,
• reduced added resistance of eight percent, but at some wave
frequencies up to 30 percent!
This new vessel has been operating successfully for a year in this
notorious stretch of water, and is the smallest vessel in the area. It
does prove, however, that tank testing is a worthwhile investment.
So why wouldn't a builder or owner of a new build decide not
to spend $30,000 in basic tank testing? Arrogance or stupidity
mainly, sometimes a combination of both. All of us know vessels
that don't go well, or run in bad trim, or behave poorly in a
seaway, just because the owner was not diligent.
In the new world of energy footprinting, tank testing of
proposed new vessels should be undertaken as a matter of
commercial diligence, and environmental responsibility
So instead of trying to save some money for your next ship and
spend your weekends combobulating, consider contacting Mr
Gregor McFarlane and his centre of excellence down at the AMC.
The vessels in the Bahamas, Scotland, and Holland mentioned
above are just a brief testimony to what should be done.
With STUART BALLANTYNE
THE EDUCATION OF AN
September 2009 AUSMARINE
A catamaran model undergoing testing at the Australian Maritime College
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