Kulluk Grounding and Prince William Sound Escort Tugs

Maritime Topics Tugs & Towing
1

Interesting article about the escort tugs in PWS:“With Kulluk grounding we’ve been warned”

Now, however, we have seen a real-world heavy-weather towing emergency unfold and the results were are not reassuring. The Kulluk incident involved a brand new tug with over twice the horsepower of the Prince William Sound tanker escort tugs, yet it lost its tow line no fewer than five times before the Kulluk grounded near Kodiak. This demonstrates just how difficult towing is in severe Alaskan weather. Bad storms happen all over Alaska, and severe weather just outside of Hinchinbrook Entrance — where loaded tankers leave the Sound — is common, more so than in the western Gulf of Alaska where the Shell rig ran into trouble. That’s why meteorologists nicknamed the northeast Gulf of Alaska “Coffin Corner”.
It’s also why loaded oil tankers are not allowed to pass through Hinchinbrook if weather there exceeds 15-foot seas and 45-knot winds. But even that is no guarantee they will avoid extreme conditions. The well-known coastal weather phenomenon called barrier jets often creates high winds and big waves just outside Hinchinbrook, even when the weather inside is much milder.

K.C.

2

The KULLUK incident (and some of the other incidents that have happened in the Aleutians over the past few years) certainly do point out the need for having an adequate number (perhaps four to six) of the best technology available powerful rescue towing tugs stationed around the Gulf of Alaska. The stand by stations that come to mid are: Sitka, Icy Bay, PWS, Homer, Kodiak, and Dutch Harbor.

These incidents also point out the need for oil rigs, barges, and ships transiting these areas to have excellent emergency towing arrangements ready to go so that they can be promptly taken under tow. Also, the ship’s emergency towing gear must be deployed before the ship is abandoned to facilitate an unmanned ship being picked up by a tug.

A permanently manned USCG helicopter base has been needed at Dutch Harbor for as long as I can remember.

This won’t be cheap, but the cost of all this would not add one cent to the price of a gallon of gas at the pump.

3

I think there is a adequate amount of tugs available for rescue in my opinion, you can have all the hp in the world but doesn’t do any good if you cannot get control of the drifting barge/ship there are 2 tractors in Dutch year round 4500hp each. 2 in anchorage, 1 5000hp in nikiski, 1-4,000hp in Kodiak, 4 10,000hp tractors in Valdez year round. Plus various conventional tugs always around. The problem in my book is the emergency towing gear. The coast guard said it had some in various spots maybe it needs to be located always on the specified tugs at these ports ready to go. Just my opinion.

4

[QUOTE=rshrew;94932]I think there is a adequate amount of tugs available for rescue in my opinion, you can have all the hp in the world but doesn’t do any good if you cannot get control of the drifting barge/ship there are 2 tractors in Dutch year round 4500hp each. 2 in anchorage, 1 5000hp in nikiski, 1-4,000hp in Kodiak, 4 10,000hp tractors in Valdez year round. Plus various conventional tugs always around. The problem in my book is the emergency towing gear. The coast guard said it had some in various spots maybe it needs to be located always on the specified tugs at these ports ready to go. Just my opinion.[/QUOTE]

Well, your certainly in a much better position to make such an assessment than I am. I agree that Cook Inlet and PWS are well covered with rescue tug capability.

I still would like to see a tug at least the size of ALERT (and without any commitments that cannot be promptly set aside in an emergency) on station in Kodiak and somewhere in Southeast Alaska.

I think that Dutch Harbor needs something much bigger than ALERT, perhaps more like TOR VIKING II. The tractor tugs in Dutch have ship assist commitments, and I do not believe they are up to the task of rescuing ships hundreds of miles away in bad weather the way TOR VIKING II did off Atka Island. (Wasn’t that last winter?) I’m thinking of a large ice class salvage tug with the ability to respond to an emergency in Arctic, off Attu, in the Gulf of Alaska halfway to Puget Sound, or halfway to Hawaii.

5

I know there was talk of a rescue tug in Dutch after the Tor Viking rescue but never heard anything more about it. Time will tell now after the kulluk debacle.

6

[QUOTE=rshrew;94962]I know there was talk of a rescue tug in Dutch after the Tor Viking rescue but never heard anything more about it. Time will tell now after the kulluk debacle.[/QUOTE]

but who on earth pays for a tug to just sit there? The days of the world having salvage tugs positioned in strategic locations around the planet is over with the reduction in ship casualties and the refusal of any shipowner to allow one of their masters sign a Lloyd’s Open Form.

Did the Neah Bay Foss standby tug ever save a ship is distress or does it just cost the State of Washington a whole buttload of money each year? Do they still even have it sitting out there?

7

That’s the problem know body wants to pay for it nor is it really needed in my opinion. And yes Foss still sits in neah bay year round with the Jeffery Foss. They have not done a tremendous amount of “rescues” to date. Nothing that could not of been done by a tug out of Anacortes or Port Angeles. Talk about a boring job! But good money for not using the equipment and getting paid every day of the year!

8

This is like asking who pays for the ambulance and fire trucks to stand by just in case something might happen. Or why pay all that money for these guys to do nothing most of the time. Given the kind of Money that government wastes everyday (look at TWIC or any MARAD program), the cost of a couple of rescue tugs is trivial.

If paying for a couple of big rescue tugs to stand by in Alaska, just in case an unthinkable event might happen (like the KULLUK grounding), will help to prevent a moratorium on Article drilling, I am willing to help pay for it, every time I pull up to the gas pump.

9

Nothing’s preventable that’s the problem, especially in Alaska. Would it make a difference? Maybe, they have escort tugs so tankers never spilled oil again in Valdez has that happened since? No the escort tugs ran aground a spilled oil. Apples to Oranges in my opinion it’s not needed. What is needed is common sense by people calling the shots in an office.

10

For sure. And dutch actually has a ETS system on standby. Both tractors train and use once ever y year. Rough big weather with that questionable…however pretty cool package if you ask me. Shot via line gun or dropped by heli. Could buy enough time to get control and maintain.

11

There was also this bit about studies that the tow winches on the current tugs require upgrading.

Specifically, the study called for more modern winches that can automatically pay out and reel in tow lines under full load. The winches now on the Sound’s tugs represent 15-year-old technology and they lack this capability.

The modern winches recommended by the Allan study permit tugs to apply full towing force and reduce or eliminate the huge tow line surges that come from vessels getting thrown around in big seas. These new winches are designed to help prevent tow line failure by reducing shock loading on the system.

Most towing exercises in the Sound happen in relatively calm weather. The advantages of the new winches do not become apparent until the weather gets rough. With so many successful escorts and exercises behind them, industry and its regulators have grown comfortable with the old-style winches, and they declined to act on our towing equipment study recommendations. Similar recommendations from a study by the international ship classification society Det Norske Veritas a year earlier were similarly dismissed as unnecessary by the industry and the state.

Now, however, we have seen a real-world heavy-weather towing emergency unfold and the results were are not reassuring. The Kulluk incident involved a brand new tug with over twice the horsepower of the Prince William Sound tanker escort tugs, yet it lost its tow line no fewer than five times before the Kulluk grounded near Kodiak. This demonstrates just how difficult towing is in severe Alaskan weather.

K.C.

12

This was always released in the Anchorage Daily News as an OpEd and the entire piece is attached here

[B]Compass: New and better technology is needed for rig towing vessels[/B]

Published: January 16, 2013

By MARK SWANSON

The grounding of Shell Oil’s Kulluk drill rig reminds us again of Alaska’s tough maritime conditions and our vulnerability from coastal shipping and oil activities in the Arctic and around Kodiak, the Aleutians and Southcentral Alaska.

Rescue vessel crews persevered through a tough response to save the Kulluk. We Alaskans owe a huge vote of thanks to responders who risked lives and equipment to save the rig.

Maritime activities go on constantly, often in weather too rough for meaningful response to accidents. The Kulluk isn’t the first vessel to lose power or a tow and be blown ashore in Alaska. It won’t be the last. Hand-wringing won’t help.

We have to prevent accidents, including additional oversight. Citizen advisory groups like ours could be an important part of that oversight.

The Kulluk incident is an object lesson in the need for best available technology in towing operations and equipment, a lesson that should be applied in Prince William Sound and elsewhere.

Our council, working with the internationally respected naval architecture firm of Robert Allan Limited, completed a study last fall that recommended, among other things, installation of the best available towing technology on the tugs that escort loaded oil tankers through Prince William Sound.

Specifically, the study called for more modern winches that can automatically pay out and reel in tow lines under full load. The winches now on the Sound’s tugs represent 15-year-old technology and they lack this capability.

The modern winches recommended by the Allan study permit tugs to apply full towing force and reduce or eliminate the huge tow line surges that come from vessels getting thrown around in big seas. These new winches are designed to help prevent tow line failure by reducing shock loading on the system.

Most towing exercises in the Sound happen in relatively calm weather. The advantages of the new winches do not become apparent until the weather gets rough. With so many successful escorts and exercises behind them, industry and its regulators have grown comfortable with the old-style winches, and they declined to act on our towing equipment study recommendations. Similar recommendations from a study by the international ship classification society Det Norske Veritas a year earlier were similarly dismissed as unnecessary by the industry and the state.

Now, however, we have seen a real-world heavy-weather towing emergency unfold and the results were are not reassuring. The Kulluk incident involved a brand new tug with over twice the horsepower of the Prince William Sound tanker escort tugs, yet it lost its tow line no fewer than five times before the Kulluk grounded near Kodiak. This demonstrates just how difficult towing is in severe Alaska weather.

Bad storms happen all over Alaska, and severe weather just outside of Hinchinbrook Entrance – where loaded tankers leave the Sound – is common, more so than in the western Gulf of Alaska where the Shell rig ran into trouble. That’s why meteorologists nicknamed the northeast Gulf of Alaska “Coffin Corner.”

It’s also why loaded oil tankers are not allowed to pass through Hinchinbrook if weather there exceeds 15-foot seas and 45-knot winds. But even that is no guarantee they will avoid extreme conditions. The well-known coastal weather phenomenon called barrier jets often creates high winds and big waves just outside Hinchinbrook, even when the weather inside is much milder.

The questions raised are obvious: What if the Kulluk had been a loaded oil tanker experiencing a loss of power in a storm or a barrier jet along the rugged coast just outside Hinchinbrook? Would a rescue have been possible? What happens around the rest of coastal Alaska when a large vessel loses power and no suitable rescue tug is around?

We don’t have answers to those questions, but the Kulluk incident makes a few things clear about what’s needed: An ample supply of equipment – with backups – for preventing accidents, meaningful oversight of maritime risks and the use of best available technology – such as towing winches that automatically pay out and retrieve – in our rough Alaska waters.

Mark Swanson is executive director of the Prince William Sound Regional Citizens Advisory Council.

Read more here: http://www.adn.com/2013/01/16/2755256/compass.html#storylink=cpy

13

You can tow in rough wx as long as you have enough tow wire out! Rapp Hydema makes a niffty automatic tow winch that pays in and out with tension for ocean towing. Say wouldn’t a 220 million dollar tug like the Aiviq have tension meters and a fancy winch like this? If so wouldn’t they have let out wire to easy tension? Wouldn’t they have used surge gear sufficient enough for the tow? Wouldn’t they have had proper rated shackles? Would love to see that tow plan the USCG approved.

14

Markey render-recover on a towing machine has worked slick for connecting a tow wire in crap Wx but obviously i’ve never seen anything that works under a heavy load or for that matter on the scale we’re talking.

I have however been able to keep a barge alongside in rougher than normal conditions using max render on the headline. Slightly unnerving with the generator loads on an electric drive winch though.

Someone outlined the probable towing machine arrangement on the aiviq and it must have some kind of tension meter.

15

[QUOTE=anchorman;93124]TheAiviq has a Rolls Royce 500ton reverse waterfall (3) drum main winch. It also has secondary winches rated for 170 tons. Three inch wire is non-existent on these vessels, and typicaly have 3-5/8" deadman into the towing drum just to accommocate a larger wire, and more than likely have 4"-4-1/2" towing wire at the very least. I’m not sure of the exact arrangement of their tow, but I would imagine they had a 3-1/2" length of chain at the stern roller, maybe 30 feet long. In this case, if they were smart, they would have been towing on a dynamic break during this period. Rolls Royce recommends unclutching the tow drum during towing, and just have everything on the brakeband. There is an installed loadcell located in the rocker that will tell you tonnage readings on the wire, while on the brake. You can set alarm points, but those are just warnings. Being clutched-out and on the break in this method allows you to trips the tow wire in a hurry, for safety reasons.The brake also will limit the speed via inputs from magnetic pick-ups that count the teeth on the main gear if you just dropped the brake to save the ship.
Although, not recommeded by the manufacturer, you can tow dynamically where the winch will release tension automatically. The tonnage is read by a different means - by a pressure transducer located in the first chamber of the hydraulic pumps (thesse are 3 chamber low pressure motors). This provides flexibility for these very large winches. You can turn off individual motor chambers - same volume, but less area, gives you more speed, but less torque. The winch is faster, but not as strong. You also must have the correct wire size and length on the drum so the tourque can be accurate calculated by radi from drum center.
[/QUOTE]

This is from the other thread.

K.C.

16

From Reassessment of the Marine Salvage Posture of the United States

SALVAGE TUG REQUIREMENTS
GENERAL

The power required by a tug to tow a ship is a function of many variables. First, the size of the ship and its general characteristics influence the effect of the wind and wave forces acting upon it. Second, the size and characteristics of the tug as well as the type of propulsion are significant factors in determining not only the magnitude of the environmental forces acting on it but also its ability to operate in that environment. Last, but not least, the towline arrangement and the experience and expertise of the tug master and crew have a large bearing on the ability to tow in heavy weather.

When evaluating the ability of a tug to tow a vessel it is necessary to understand the dynamics of the situation. A tug towing a tanker can be represented for analysis purposes by three components:

A mass representing the ship, which is acted upon by time varying accelerations, damping, and spring coefficients.

A nonlinear spring representing the towline.

A mass representing the tug, which is also acted upon by time varying accelerations, damping, and spring coefficients.

This is a very complex system both from a theoretical point of view as well as in actual operation. The multiplicity of time varying forces and resulting motions combined with the nonlinearity of the towline can lead to extremely high dynamic loads on the system in heavy seas.

While one might prefer to think that any size vessel could be towed in any weather with a large enough tug, this is simply not the case. The limiting factor is a function of the relative motions between the two vessels and the ability of the towline and towing winch to allow for that relative motion without breaking, while still providing sufficient towing force to keep the vessel moving or at least to maintain its position. It was demonstrated—most dramatically in the case of the Amoco Cadiz—that even a world-class tug cannot tow a vessel under some conditions. The relative motions between the two vessels simply becomes too great for the towline’s ability to stretch. Attaching a towline is a difficult and dangerous operation in storm conditions and may not be possible, again, due to relative motion between the vessels.

Tugs use several different methods to provide the stretch required in a towing system. First, an ocean towing winch may be designed to automatically pay out and heave line as the tension varies. This helps to reduce major shock loads. Next, the length and weight of the tow wire results in a catenary, which allows for some degree of relative motion between the tug and ship. Finally, the use of a doubled nylon hawser as a shock absorber within the towline adds stretch to the system.1,2 Together these allow substantial relative motion between the two vessels. While other methods are used to allow for relative motion between the vessels, the above are the most common.However, as the relative motion nears the limits of the winch, catenary, and hawser system capabilities, the towing arrangement will either become very stiff, with consequent large shock loads, or the winch will pay out more line than it can recover. In either case, the tug will be unable to continue towing.