Anchored Vessels Behavior in Wind

As has been said there is lot of variation from ship to ship.

On a small Aleutian freighter we were anchored snug as a bug off St Paul Island a few years back. We didn’t have any special gear, single anchor, only 4 shots out (all the “good” chain we had), no worries.

The All Alaskan was anchored a few miles from our position, don’t know what kind of anchor gear she was using but she drove up onto the beach that same night.

The 340 foot steel fish processing ship ALL ALASKAN ran aground in a gale on March 20th, 1987 north of Big Lake on Saint Paul Island. All 142 were saved. The wreck was heavily salvaged. Evidence may still be on the site. Owned at the time by All Alskan Seafoods, Alaska, USA Read more at wrecksite: https://www.wrecksite.eu/wreck.aspx?216189

The All Alaskan was sister ship to mine, and she went up on the beach right at the beginning of my time in Alaska. Story I heard was that they were anchored on the north side of St. Paul and the skipper rotated off the vessel before the new skipper got aboard. In the Pribilof Islands, it’s a real pain to get from the “airport” to the ship, especially if it’s up on the north side. It takes many hours and good luck. The wind switched to northish and the mate wasn’t able to (and shouldn’t have had to) get underway for a better anchorage. They swung around with their butts to the beach and got set ashore. Everywhere around St. Paul is pretty good hard sand holding ground, so it might just be that the their anchor didn’t re-set before it got too shallow. That north end is a real gradual shallowish slope from what I remember.
A couple of years later, another sister ship, the Yardarm Knot, mis-navigated their way around Northeast Point and tore out their bottom, floating on the tank tops as they say. They anchored up, but found themselves in a similar situation to the All Alaskan, with their stern to the beach in a rising northerly. They were actually bumping bottom until the mighty tug Malolo managed to tow them into deeper water. That was an exciting night.

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I didn’t know there was a relief captain on the way out. I did hear that the off-going captain’s flight was canceled due to bad weather and he was at the airport or at least still in St Paul when the ship went aground.

We were alongside the All Alaskan for most of the day before transferring product from and fuel oil to. We cut loose that afternoon sometime because it got too rough to continue.

We went and dropped anchor in the lee side of St Paul planning on finishing up the next day but they were on the beach.

That’s how I remember it from thirty years ago anyway. Man, it’s amazing that that era of cowboy fish processors pretty much came and went without huge loss of life.

The use of anchors is a whole interesting study of its own. As second mate I was on the forecastle when we anchored at an ill judged speed on a VLCC. We quelled the flames from the brake drum with fire hoses until the 8th shackle came and went and I instructed all hands to beat the feet. The requirements for warships to anchor in confined areas used to moor to reduce the swinging room and a swivel was inserted into the two chain rodeos. The swivel had 3 links on one side and 2 on the other so the cables were reconnected to the correct side. At one stage serving on a training ship we carried out the evolution with every new intake of seamen.
The method of stopping the vessel yawing discribed by Dutchie was also used. A “joggle” shackle connected a wire from the stern to the ship’s cable and the cable paid out until the ship was at the desired heading. I used this method once to lay a warship alongside a wharf that was so ramshackle that we didn’t want to touch it. We ran the hawsers to trees . This method was more commonly used for ceremonial occasions where the ship or ships were required to lie on a specified heading for say illuminating ship.

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11 posts were split to a new topic: Anchoring Downwind and Variations

The traditional cure for sailboats that want to sail up, luff and fall off on their anchor rodes is said to be more windage aft, to counteract the bare-poles situation of the center of effort forward of the center of resistance. I’ve never sailed a yawl, but this is supposed to be one of the nice advantages of a yawl at anchor in a breeze. Setting the mizzen, sheeted in fairly tight, is supposed to keep the boat weather-vaned into the wind (and “luffing” under bare poles) so that it rides head to wind on the anchor rode and does not try to reach off and sail up on it as in your diagram. In the large foretriangle sloops that I’ve owned, I’ve noticed some tendency to do this just from having the cockpit bimini up, especially if I have some of the side-screens zipped in.

You can get a riding sail that shackles to the backstay for this effect. Also going to more and heavier chain helps some, as does a kellet.

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If it’s bad enough that I am concerned by excessive yawing or stress on the gear I am getting out of dodge and taking my chances hove to somewhere far windward of the lee coast. Anchors are great but not for extreme conditions.

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I agree, evidently use of multiple anchors is the practice with large ships in some situations. Most of the anchorages I use are crowded, I don’t recall seeing anyone use more than on anchor as a standard practice.

I’ve seen three different ways a ship can drag.

On small ships which don’t horse around they just drag slowly straight down wind. A couple extra shots is the cure here.

The second way is when a ship horses around, at the end of each run perpendicular to the chain it will give the anchor a yank and pull it downwind a meter or two. I have just left it like this if it’s clear downwind. In the morning the ship can be re positioned. This is not without risk.

The third way is the ship can turn and put it’s beam to the wind and drag the anchor downwind at two or three knots. The only way I’ve gotten out of this situation is with the engine.

The anchor under foot will cut down on horsing around but it leaves the risk of the beam -to run downwind as a anchor on a short stay will provide little extra holding power.

The two anchor laid out will reduce the risk of the beam-to run but a ship jacking around is going to pull on one chain at a time.

This is not to say anything about the seas and swell.

The recommended practice in my case is to avoid anchoring if bad weather is forecast or to get underway if bad weather is expected.

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Thinking about this a little more, P&I clubs and charterers in general that have access to large amounts of data rather than anecdotal evidence tend to recommend the lower risk option of avoiding being anchored in bad weather.

In that case the captain would be faced with the risk of utilizing a procedure that is not recommended.

If the advantages and limitations of using an extra anchor is well understood in a particular application and two anchors is expected procedure that would be a different matter.

There was a video on YouTube a couple of years ago that showed a bulkcarrier still at anchor in unbelievable conditions. Why the guy didn’t get out of Dodge when the weather was forecast to deteriorate I don’t know. In another case same circumstances a large bulk carrier ended up on the beach at Newcastle, New South Wales.

Measures that can be taken to diminish yawing, apart from the methods already mentioned, could be:

  • Increase draught by taking in ballast water (consider stability),

  • Trim by the head (maintain propellor immersion),

  • Veer more anchor cable (difficult in rough seas),

  • Drop the other anchor (danger of fouling of cables),

  • Use of bowthrusters (must be kept submerged, are endangered if pitching and rolling),

  • Use of the main engine in combination with steering (beware of sudden tension on anchor cable, danger of breaking out anchor).

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ECDIS image

Early detection of dragging of an anchor is important. In addition to the usual methods of checking the vessel’s position by reference to fixed points such as buoys, church steeples etc and the use of radar, there is these days also the possibility of using the ship’s wake indicators in ECDIS.

I think the issue with the Pasha Bulker, aside from not getting underway when the getting was good was not enough room to get the ship under control. If the ship is beam-to it’s going to be a mile or two before the ship can be brought under control.
What has worked out for me is using the engine to get the bow into the wind and then recover the anchor. But you need the searoom to your lee.

Here is an old article, not about anchoring but just handling a car ship in the wind:

Marine Accident Reporting Scheme MARS [Report No 190 August 2008]

Ro-ro ships – manoeuvring difficulties

An inbound pure car and truck carrier (PCTC) was approaching the pilot station at her scheduled time, in very confined waters. A gale warning was in force and with only two miles to go to the pilot embarkation point, the wind suddenly increased and pilotage services were abruptly suspended.

The master was instructed to await further orders and decided to head back to open waters rather than wait in the confined area or anchor there. The wind caught the beam of the high-freeboard and low draught vessel, and started setting her on to the lee shore, less than two miles downwind. Using full rudder and engine power, and transmitting appropriate signals on the air horn and VHF radio, the master just managed to turn the ship’s head into the wind and execute the 180-degree turn and head out to open sea.

Once out of the lee of the land, the full force of the gale caused the ship to move sideways at about five knots, even with the engine going on harbour full ahead. The vessel remained stubbornly beam on to the wind despite all attempts to heave to with the head into the sea and swell. This type of vessel has been rightly described as a ‘ping-pong ball on the water’ and under high wind con
*Even with full scope of chain on both anch ors, ro-ro vessels tend to yaw violently in strong winds and the ‘jerk’ at the extremity of each yaw may cause the anchors to drag! especially if the holding ground is less ![image|640x441]g) vessel in high winds, must allow for a greater margin of safety.ditions, ro-ros are almost impossible to control or manoeuvre.

At the first indication of approaching strong winds, masters of ro-ros and similar high-sided vessels must not hesitate to leave port or confined waters and anchorages and head out to open sea. Maintaining a safe position under way in the lee of a high offshore island is a safe option, provided the location and predicted movement of the weather system is known.

If sailing from port is not possible, ships have been kept alongside with continuous use of tugs, and, in uncrowded anchorages, mooring to two bower anchors may considered, but with engines in full readiness until the wind has abated.

Even with full scope of chain on both anch) ors, ro-ro vessels tend to yaw violently in strong winds and the ‘jerk’ at the extremity of each yaw may cause the anchors to drag, especially if the holding ground is less than ideal.

Mariners whose vessels may be navigating or lying at anchor near a ro-ro vessel in high winds, must allow for a greater margin of safety.

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The above is from this thread:

Which has this photo of the All Alaskan

image

They’re all top and no bottom, like bread trucks. I’ve seen a clip of a cruise ship in harbor skating sideways at what looked like five knots.

Yawing%20Anchoring

  • She drifts beam to wind
  • You send the CO, the Bosun and AB’s fwd
  • You let go stb’d anchor
  • You let the chain out to 4-5 shackles
  • You put the brake easily to get 5-6 shackles out
  • You let the vessel yaw to port
  • Once you get her on maximum port yaw, you let go port anchor
  • She starts to yaw to stb’d, you let the port chain go free, you heave on the stb’d one
  • Once you get 3-4 shackles on the port chain and 5-6 on the stb’d one, you hold both.
  • You can walk out more chain if she drift
  • You get down on your knee and make a prayer expressing gratitude that everything went as planned! :anchor:

Yep, that photo of the All Alaskan looks familiar. She laid there for quite a while, and while she did, the hydrodynamic forces scoured out dandy landing basins just inside the bow and stern for our skiffs trying to get ashore at the north end of St. Paul. They eventually broke her apart bit by bit and trucked her overland, I suspect to be loaded on a barge for her final resting place.

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A minor point, Dutchie, but I suspect the ship grounded off Newcastle, Australia is the Pasha Bulker, https://duckduckgo.com/?q=pasha+bulker+photos&t=osx&ia=images&iax=images&iai=http%3A%2F%2Fwww.abc.net.au%2Fnews%2Fimage%2F67524-3x2-940x627.jpg

River Torrens grounded inside the harbour.

I have anchored a 10-ton full keel sailboat (Atkin Eric) in hurricane force Cat 2 and 3 winds. The first was in Papeete the crowded anchorage in Tahiti where anchored boats randomly charged each other. They all reacted differently. It seemed to depend on the hull and topsides configuration as well as scope. At the start of a new gust, I had to power into the wind to set up which tack to use to avoid nearby charging boats. The second, stronger storm anchorage was at the end of a long narrow valley. we quivered on our anchor rode for 13 hours. I wrote more about it here: “A hurricane story” by 40 years a Sailor https://link.medium.com/oFxoPGDzJV
Ahh the memories.