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 barge.

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”.

Radio Controlled

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.

Safety

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.

Switcher Boat

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.

Hydraulic Propulsion

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”.

Reliable

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.

360° Steering

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 duty”.

Efficiency

“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”.

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