Tanker towing tug?

[Rebel112r]

Picked up tanker and tug on ais, nothing unusual. Noticed from ais that tug was behind tanker both southbound at 10 knots. Figured tug was just keeping the tanker company. As they got closer I could see thru the binocs, that tug had a line to stern of tanker, line attached to stern of tug. As they got closer could see that indeed tanker which was loaded was indeed towing tug. This was in the PNW, in the shipping lanes, west of Lummi Is. Seems an odd way to be hooked up to a tanker. Any ideas out there? Tug was Lindsay Foss.

 

[FlyWright]

It's a tanker dinghy! They do that here sometimes, too. I always thought it was the Bay Pilot's ride.

 

[markpierce]

See this routinely for tankers going up Carquinez Strait to the refineries. The ship isn't towing the tug. It's to help maneuver the tanker. And typically, there is an escorting tug too.

 

[Edelweiss]

Yup . . . see that all the time. Indeed they are towing the tug backwards down through Rosario Straits to Davidson Rock where they make the turn to enter the Westbound Vessel Traffic Lane. They seem to drop the tow there and the tug just escorts on out to Port Angeles.

I just assumed that they were assisting with steerage, but is a good question for some of the merchant marine guys??

PS: OK I couldn't stand it so I called a friend who works for Crowley Maritime and he sent me this information on the Lindsey Foss and Garth Foss which answers your question:


Voith-Schneider Powers Tug The Garth Foss was delivered to Foss Maritime of Seattle, an^ preceded in November by an identical sistership, the Lindsey Foss.
The tugs, reportedly the world's largest and most powerful, are fitted with Voith-Schneider cycloidal propulsion units. The Garth Foss will work for BP Oil Shipping Co. escorting tankers in the Straits of Juan de Fuca and Puget Sound.
The Lindsey Foss is already working for Arco Marine, performing similar tasks.
The Voith-Schneider cycloidal propulsion system consists of two sets of five vertically oriented blades installed ahead of the tug's center. The system gives the tug 360° maneuverability and great ability to steer and stop tankers in the event of an emergency.

The Voith-Schneider unit is driven by a pair of General Motors EMD ME 16-710-G7A diesels rated at 4,000-hp each turning through propulsion unit reduction gears. A turbo coupling between the engine and reduction gear replaces a clutch. The 475-grt vessel has a running conditionspeed of 14.5 knots, and carries 83,700 gallons of diesel fuel, 2,400 gallons of lube oil and 4,000 gallons of fresh water.
A 345-sq.-ft. skeg at the stern helps the tug to steer and stop a moving tanker.
A tractor tug fastened to a ship is operated stern first, and can shear off at an angle using the skeg in combination to produce steering and stopping forces greatly in excess of the tug's static bollard pull.

The tugs feature second generation winches with high braking capacity and fast line recovery.

 

[Giggitoni]

Sailor of fortune will chime in here soon. Mark is right, the tug pulls to left or right and swings the stern around when needed. The larger tankers and container ships need speed to maneuver which they can't get in the tight quarters of the bay.

 

[High Wire]

Contract or legal requirement? To have a line on, not to tow backwards.

 

[Sailor of Fortune]

Ship assist/escort tugs. several areas they are mandatory. Tractor tugs are often seen operating "backwards".

 

[RT Firefly]

Greetings,
Probably just an optical delusion. The tug, in fact, was pushing the tanker with the rope.

 

[dimer2]

That tug has a SD hull and a fuel burn >2.5 GPH and therefore strictly for ICW use. It was found nearly a mile offshore and is being towed back to the safety of the bay by an obliging freighter.

 

[Rambler]

Maybe the tanker was refueling the tug? Kind of like an in-flight refuel of aircraft.

Or as RT says, the tug was pushing the tanker with the rope. ..... While being refueled.

 

[CaptTom]

That tug has a SD hull and a fuel burn >2.5 GPH and therefore strictly for ICW use. It was found nearly a mile offshore and is being towed back to the safety of the bay by an obliging freighter.

Yes, they would have just anchored, but couldn't agree on which anchor to use.

 

[psneeld]

Towing tends to keep you going straight when going slow even when there is crosswinds or currents...and I'm sure a tractor tug on a short leash is just like having a stern thruster for slow speed /close quarters maneuvering.

My company often has a second boat attached to the stern of the tow when towing large boats/barges through narrow span draw bridges.

 

[Rebel112r]

Thanks for all the replies. There was another large tug there but he was just keeping pace about a mile from the action. The tug on the tether was making a pretty good stern wave, and it was a fairly short line between the two. DS

 

[Anthonyd]

When I was working for a towing company out of Jaxport, some vessels need a tug to go stern to stern and assist in making the turns. Some of the newer ships have a Becker rudder, or flap rudder. This is a two piece rudder and the flap can bring the rudder into a 60 degree position to aid in tight turns, so no tug is needed at the stern. It just depends on the ship.

 

[DCBD]

One thing for sure, whether it's pulling or pushing, being towed or refueled, SD or couldn't decide on which anchor to use... it's a pretty impressive piece of equipment. Did it come with new tires?

 

[alormaria]

Try saying "Voith-Schneider cycloidal drive" 3 times quickly.