Bow Boat for Barge Tows
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> Bow Boat for Barge Tows
The other skippers shake their heads in disbelief. They
have been windbound for two days, but Breathwit Marine Contractors
still runs a 3 barge empty tow at 7 knots. The West end
of the Intercoastal Canal with all its narrow bends, river crossings
and locks is hard enough to maneuver in nice weather. But
with a 45-50 MPH wind, it is virtually impossible to hold a two
barge tow. Not for Breathwit Marine Contractors.
They run three barges loaded or empty. Their secret weapon?
A radio-controlled bow boat tied to the front end of the lead
Walt Breathwit designed and built the boat himself.
It is a 55 x 28 x 7 ft. unmanned mini-tug with a Thrustmaster
azimuthing propulsion unit installed in a slot at the stern.
The boat is provided with push knees at the bow and at the stern.
Walt looked at many different types of bow boats and propulsion
machinery before he made up his mind. Walt explains:
“We were looking for ways to increase payload per trip
and increase the number of trips per month. A bow boat
can do that. But not just any bow boat”.
The bow boat is operated by UHF radio link from the tug pushing
the tow. Walt has friends in the towing business who have bow
thrusters with electrical controls. “Talking
to friends with cable controlled bow thrusters, the cables would
not hold up on rock and sand barges. And when the tow breaks
up in bad weather, you break the cable and lose control over
the bow boat. The radio is much more convenient and reliable.
My crews just love it”. The radio control box
is portable with plug receptacles for power and antenna cables.
It can be used from any boat equipped with a proper antenna.
The control box has joysticks for steering and power (proportional
forward-neutral-reverse) and engine speed. It displays
steering direction for full 360° steering. It also
displays engine RPM and function alarm status. An emergency
stop pushbutton allows remote shut-down of the bow boat engine.
Much attention was paid to the safety aspects of using radio
controls. The radio link transmits coded streams of digital data.
The unique coding prevents any stray signals from affecting the
operation. The system is provided with automatic diagnostics
and it regularly checks itself for proper operation and component
condition. Moreover, the propulsion machinery automatically
declutches and engine speed goes down to low idle when the radio
signal is lost for more than five seconds.
The bow boat has its own wheelhouse with controls. A
selector switch gives a choice between radio remote operation
and local control. With the switch in the local position,
the boat can be used as a small tug. It is powered by a
350 HP engine driving a 360° steerable thruster with a 58”
propeller. The thruster provides maximum thrust in any
direction making the boat extremely maneuverable. It is
ideal as a switcher boat for making and breaking up tows.
The hull plating is 3/8 and ½ inch thick, containing
five separate compartments. The engine is housed in a deck
mounted engine room. The thruster is installed in a slot
or keyway in the stern of the boat. The lower tip of the
propeller is even with the baseline of the hull, leaving the
thrusters reasonably well protected.
The thruster and controls were furnished by Thrustmaster of
Texas, Inc., a Houston based manufacturer of bow thrusters, barge
propulsion and dynamic positioning units. The thruster
looks similar to the old Harbormaster units built by Murray and
Tregurtha. But don’t say that to Joe Bekker, President
of Thrustmaster. Joe explains: “Conventional
thrusters use drive shafts and gears to drive the propeller.
This thruster has a transmission that is completely hydraulic”.
According to Joe, the hydraulics offer a multitude of advantages.
“Hydraulics are reliable, flexible and forgiving.
Most of our hydraulic units are used in shallow water applications.
They pick up ropes, hit the bottom or drag through mud and vegetation.
They must be able to handle that. When a thruster gets
stuck on a sand bar or a ridge, it will either give or break.
We design our thrusters to give without breaking”.
A hydraulic kick-up system allows the thruster to be forced
upwards by any obstruction it hits. The unit remains fully
operational at any angle of kick-up. A lever operated control
valve allows for trimming and tilting the unit at any angle between
vertical and horizontal, whereby the unit can be tilted completely
our of the water. This facilitates easy inspection and
access to the propeller after it picks up a rope or an anchor.
Unlike a mechanically driven unit, the propeller is not directly
linked to the engine. When an obstacle jams the propeller,
the hydraulic system reliefs and compensators allow the propeller
to stop within a quarter turn, without even slowing down the
engine. The steering system is provided with similar reliefs,
allowing the thruster to be forcibly turned without causing damage
to gears or steering brake and motor.
The thruster produces full thrust at any steering angle through
360°. Walt smiles when he says: “We
move a lot faster with the bow boat. It steers without
drag. We steer with the bow thruster to compensate for
cross currents at river crossings and for side wind when we run
empties. As a test, we have made the Freeport Wiggles without
using the boat rudders with three empty barges”.
Walt feels that the steerable propeller thruster is ideal for
a bow boat. He looked at other systems also, but:
“With conventional propulsion and rudders, you just can’t
get the sideways thrust you need. Tunnel thrusters are
only effective at very slow speed. And jet thrusters don’t
give a lot of thrust per horsepower and are not built for continuous
“With the bow boat we went from 6 trips with 2 barges
per month to 6 trips with 3 barges. With the thruster,
we are able to keep our barges from running into the banks or
the locks. My hull repair expenses are less since we started
using the bow boat”. Walt is planning to build
his second bow boat. “I learned a lot when I built
the first one. This one is going to be even better.
I think we’ll see a lot of these in the future. The
economics are just too good to ignore”.