Freak Waves!

[Nausikaa]

My recent post under the topic 3 Blue Whales Killed By Ship Strike In So Cal Area In 2 Weeks in which I mentioned the British ship Benarty brought to mind another event: that of another of the same company's ships, the well found cargo-passanger liner Bencruachan

The ship was built by Charles Connell in Glasgow in 1968 and she has gone down in history as the last ship that yard built. Named Bencruachan after a Scottish mountain (ben being the galic for mountain) and registered in the port of Leith, she was a steam turbine ship (probably the last steam turbine general cargo vessel built for the British merchant navy, although steam turbine tankers and containerships were built later), she was of some 12,092 grt / 14, 884 dwt and had a length of 558 feet. The ship was eventually scrapped i Kaosuing in 1980.

The ship was on her way home to the UK in early 1973 after her regular voyage to the Far East. Suez had been long closed at this time and the ship was heading back for Europe round the Cape of Good Hope. Not having the "legs" to steam all the way without replenishing her bunkers she was due to call at Durban for oil. Some of you reading this may recall the days when maybe twenty vessels were lying anchored off Durban waiting to enter the port solely for bunkers? Congestion was the norm and as the Bencruachan neared Natal she was given new orders to proceed to Cape Town for bunkers due to extremely severe congestion at Durban.

The Bencruachan never reached Cape Town. She was steaming southwards at 21.5 knots in moderate sea and a sw wind of about force 4 -5 when she was struck by a freak wave off the Transkaai in the wee small hours of 2nd. May. In reality, she was not actually struck by a freak wave but fell into a hole in the sea before the following waves washed over her. The ship survived the incident but only just. The first two cargo holds were completely flooded and the keel was twisted 13 degrees out of true by the force of the sea bearing down on the ship. The main deck was a complete mess with deck cargo which had been carried away or seriously dammaged and, due to the floding of the forward holds, the ship was down by the head with her propeller clear of the water.

A MAYDAY message was sent and later the same day the passangers were helicoptered off thanks to the efforts of the South African Air Force. A sea-going tug was despatched to the aid of the vessel and on arrival connected the towline to the stern of the dissabled Bencruachan. She was then towed stern first to Durban where she was pumped out and the dammaged cargo was discharged. Doubling plates were welded on to strengthen the hull and permission was granted by ship surveyors for the Bencruachan to proceed at three (!!!) knots to Rotterdam where permanent repairs were made.

This particular stretch of the South African coast is noted for these "freak waves". They occur where the Agulhas current is strongest and where southbound ships would like to be to gain the greatest benefit of the favourable current. Northbound ships hug the coast instead hoping at best to benefit from the counter current or at least to avoid the Agulhas curent. Not long before the Bencruachan incident another British ship, the Port Chalmers also suffered the effects of a "freak" wave. She however was more fortunate and was not seriously damaged.

Other vessels have not been so lucky:

In 1909 the British liner SS Waratah on her maiden voyage from Sydney to London dissapeared after having called at Durban for coal. No trace of the ship or her 211 passengers and crew was ever found.

In 1944 the cruiser H.M.S. Birmingham plunged into a deep hole and thereafter was overwhelmed by a huge wave. The C.O. reported wading through knee-high water on a deck more than 60 feet above sea level.

Another incident occured in June of 1968 when the tanker World Glory, carrying 49,000 tons of crude oil, encountered an abnormally large wave 105 km east of Durban and broke in two. Both halves were lost.

Again in 1973, on a week or so after the Bencruachan incident the Singapore registered cargo vessel, Neptune Sapphire, on her maiden voyage, was struck by a "freak" wave in the same spot. The impact caused the bow and 61 m of the forward part of the ship to break away and sink. The remainder of the ship was towed into East London.

In 1980 the supertanker Esso Languedoc was also struck by a freak wave.

The list is certainly longer than this and the museum in East London holds a plaque with the names of all known incidents of ships dammaged or lost of the coast. Not for nothing is this know as The Wild Coast!

What does this tell us yachties? Well my advice is to keep within a few miles of the shore when sailing between Durban and Port Elizabeth.

Aye // Stephen (Formerly fourth officer of the SS Bencruachan

[svjacaranda]

Our son was doing a "Semester at Sea" program when the large ship he was on got hit by a rogue wave in the North Pacific disabling the ship. The student filmed onboard footage was pretty amazing. We did question North Pacific in Jan when he was signing up for the program. The University of Pittsburg has since discontinued the trip across the North Pacific in winter.

http://www.dailynexus.com/article.php?a=8883

Amazing when I Googled looking for this article over 100,000 hits on rogue waves!

Here is an interesting website that documents salvage of large ship accidents including some off of SA

http://cargolaw.com/ Page down a few pages to get to the report links

Chuck

Jacaranda

[Lighthouse]

This is copied from "Cruising Notes for Sailing the South African East Coast" by Tony Herrick

ABNORMAL WAVES

It is a known fact that giant waves occur on the South African coast in the Agulhas current region, where southwesterly gales prevail against the southward flowing Agulhas current. Professor Mallory of Cape Town University analysed the recorded conditions that prevailed each time a number of ships were damaged by exceptional waves, and found that in all cases the dominant waves were always from the southwest.

The weather patterns play a major part in that the most dangerous period occurs when cells of low pressure are moving along the coast in a northeasterly direction. These lows are a regular feature of the eastern seaboard and it often happens that during their passage the wind can change from a near northeasterly gale to a southwesterly gale, sometimes in a matter of minutes. The southwest wind then reinforces the existing waves generated by a short choppy sea, which acts directly against the Agulhas current.

It is the interaction between the strong southwesterly wind and the strong south flowing current which at times can reach 6 knots that creates monstrous freak waves, of which the charts warn:

"Abnormal waves of up to 20 meters in height, preceded by deep troughs may be encountered in the area between the edge of the continental shelf and twenty miles to seaward thereof".

The warning also describes the necessary evasive action to be taken under unfavourable conditions, namely, to stay clear of the areas seaward of the continental shelf. In other words, move inshore, inside the 200 meter line. This well established rule has given rise to the belief that the bottom topography plays a part in the generation of giant waves, but in fact this only plays an indirect role.

Please remember that the conditions along the southeast coast of South Africa are unique; the region can only be made safer through an understanding of the forces involved and by treating the seas with the respect they deserve, regardless of loss of time. "Do not have a deadline to meet at the other end". MANY South African sailors sail along this coastline all the time - simply prepare yourself with all the knowledge and information that is available for a safe passage.

(Reference is made to a research paper - "Giant Wave - Anomalous Seas of the Agulhas Current" - by Ecxart H Schuman.)