There have been a number of interesting ways in which
waterjets have replaced traditional prop-and-rudder
arrangements for propelling and guiding a workboat from one
point to another.
One of the most recent examples is a pair of ferries built
for the Canadian company La Traverse D'Oka that are powered by
waterjets from North American Marine Jet .
The original ferries operated by the Hudson, Quebec, ferry
service west of Montreal, consisted of an 80-foot barge that
carried up to 10 cars, and a small "Chris-Craft-looking"
"When they got to the other side, they would slingshot the
barge to turn it and get it into the slip. It took a lot of
time and was pretty unique," said North American Marine Jet's
In an effort to reduce landing times and to carry more
vehicles on the 2-km run, La Traverse D'Oka went to Navtech in
Quebec City, Quebec, to come up with two replacement
"We took the existing barges, added a hull on each side of
the barge and extended the deck between the two hulls," said
Navtech's Thomas Barbeau. By extending the deck on the
now-catamaran ferries to 120' × 36', the ferries are able to
carry 18 cars.
In place of the towboat, Navtech put a 360 SDgr Traktor Jet
457HT in the bow of one hull and the stern of the opposite
hull. Each jet is powered by a 285-hp Cummins diesel. With that
power arrangement, the ferries "could achieve the desired speed
of 7.8 knots at 1,400 rpm, and at this rpm, the thrusters were
only using 118 horsepower each," Hill said. "That's the first
time we've put 360-degree jets in a ferry."
Barbeau said that while it's not unusual to find
shallow-water ferries with jet thrusters at opposite ends of
the boat in Europe, "in North America, I don't know if this is
the first, but it's not that common."
Another application where waterjets are especially effective
is for boats that service the nascent offshore wind farm
"We are getting inquiries from naval architects and
builders," said Graham Scott with Ultra Dynamics , the builder
of the UltraJet waterjet.
Ultra Dynamics has likely been receiving inquiries because
the UK-based company has already supplied waterjets on boats up
to 72' that service wind farms in Europe.
Certainly the ability to control a boat at low speed and
zero speed is critical for the operator of a wind-farm boat.
"You need to be able to operate for many hours, sometimes at
zero speed," said Scott.
No matter where the sea and wind is coming from, a wind
tower can only be approached from one direction because the
boat's bow has to line up and fit into a single vertical tube.
"You have to approach cautiously, so control is very important.
Once contact is made you have to have a steady, solid
non-cavitating thrust at zero boat speed while the boat is
being bounced up and down," Scott noted.
So far, the company's 377 through 575 waterjet models have
been used in wind-farm boats. In 2011, UltraDynamics will bring
out its new waterjet, the 650, with an improved nozzle for
better low-speed steering.
The newest waterjet from HamiltonJet is its HT900. This
completes the HT series, which also includes the HT1000 and the
HT810. With a 900-mm (35.4") impeller, the HT900 is for large,
high-powered boats, like the 190-foot fast supply boat being
built by Gulf Craft in Louisiana. The supply boat will have
four HT900 jets onboard, each driven by a 3,434-hp MTU engine.
That should push the fast-supplier to over 30 knots at the top
end and around 25 knots service speed.
Twin Disc Inc. is now the distributor for MJP waterjets in
North and South America, the Pacific Region, Italy and Israel.
MJP (Marine Jet Power), which is headquartered in Sweden, had
been without a U.S. distributor for a while until hooking up
with Twin Disc.
"Twin Disc has been working to establish and re-establish
contacts and working relationships with boatbuilders, naval
architects and fleet operators," said Chuck Balboa with Twin
Disc. MJP jets have an input-power range of about 1,300 to