At sea off London Anchorage on route to Fanning Island to collect the recordings of Operation Grapple the British Nuclear Test. Dispatched to intercept an intruder to the test area. It was the 10,000 ton Chinese merchant ship SS Effie bound for Panama with her master unaware of the restricted area.

Extract form deck log.  1210 Assumed DC state 1

1215 State 1A Co 010 speed 22 ½ knots. One boiler banked.  All hands between decks except those in protective clothing.  Entered possible contamination area.

The ventilation was shut down as was one boiler. The engine room and boiler room were manned by personnel in protective clothing who were changed every 30 minutes to avoid heat stress

1320 Reverted to State 4. Open up ventilation. Clear of contamination area.

1330 A/C 318 degrees

The shut down boiler was then flashed up and slowly bought back on line

1414 Increased speed to 28 knots

1550 increased speed to 29 knots

1915 Arrived off Fanning Island

 

The following is remembered by Patrick Gaffney.

H.M.S. Cossack slipped out of Hong Kong harbour under the cover of darkness one October night in 1957. There were no waving well-wishers or pretty women from the girlie bars, just Dockyard mateys to let go the berthing lines. The ship had been darkened, the only lights switched on being the masthead, Port and Starboard navigation lights. We had provisioned ship and embarked a handful of civilians who brought with them several large wooden crates.

After several days at sea, we were somewhere in the Pacific, the Captain mustered the ships company on the upper deck and informed us of our mission. We were to assist the scientific people in monitoring and measuring the fallout from the Hydrogen bomb which would be detonated some miles off Christmas Islands. He went on to explain that the fallout would be minimal, but this may be difficult to achieve considering this detonation would be one thousand times more powerful than the Atom Bombs dropped over Hiroshima and Nagasaki twelve years previously.

We started our patrol to keep all shipping out of the area. Constantly refuelling, and replenishing at sea, whilst the “Boffins” unpacked their wooden crates and installed their instruments in various locations on the upper deck.

All ships intercepted complied with our request to alter course and leave, until two days before the test a Japanese fishing vessel carrying anti-nuclear protesters adamantly refused to leave. The Captain ordered the guns crew to man the guns and had them trained, almost at point blank range upon the fishing vessel. The skipper of the vessel then turned around his ship and disappeared over the horizon. November 8th. 1957, “Operation Grapple” It was a gorgeous bright sunny day without a whisper of a cloud in sight. Not a breath of wind was present and the sea was so flat it resembled a shimmering plate of glass. The silence on deck was broken when over the ships tannoy we could clearly hear the pilots voice,” approaching target area” . Fire hoses fixed vertically to the ships superstructure sprang to life spraying fountains of water in every direction .We were dressed in No.8s working rig, anti-flash hood and gloves which we always wore when firing the guns. We also wore anti-glare goggles specifically for this occasion.

The R.A.F Valiant bomber carrying the fifteen feet long cylindrical 5 ton H bomb, after reaching its maximum flying height of 45,000 feet had now reached the target area, the Cossack being three miles away.

The Boffins were hunched over their instruments anxiously twisting dials and knobs with nervous hands. Over the Tannoy we heard “Bomb gone”

We waited, in the eerie silence, tensed with nervous anticipation whilst the bomb plunged downward to the prescribed height for detonation. Cossack maintained course and speed. Then came the flash, of such brilliance it outshone the sun, and the sky seemed not to exist. In quick order a blast of intense heat that almost sucked the air out of our lungs. We clung to the storm rail, the ships plates vibrating underfoot. Then came wave after wave of rolling thunder increasing in volume and intensity with each passing second. It was as if a supernatural thunderstorm had gone out of control. Even in the vast expanse of the Pacific Ocean this barrage of sound would take several minutes to dissipate. Cossack moved slowly but resolutely forward.

The sea had been sucked upwards and vaporised into super-heated steam. Ahead of the ship we could see a huge column that would form the stalk of the mushroom. We craned our neck upwards and saw a raging inferno, angry flames shooting upward and outwards raging through black billowing smoke. Rumbling claps of thunder enveloped the ship. The sky had gone dark except for the flames shooting towards the heavens. It was as if hell was hanging suspended 5000 feet in the air. It was a staggering, terrifying spectacle almost beyond human comprehension. Cossack maintained course and speed and slowly moved from under the mushroom. Looking astern we saw a huge column of white vapour, several thousand feet high. Reaching its zenith it began spilling over forming a gigantic white dome atop the stalk of the mushroom.

Unknown at the time, the 1.8 Megaton explosion was 80 per cent larger than anticipated, and detonated much closer to sea level than planned.

As the ship moved steadily away the mushroom gradually diminished in size, and the noise abated. I remember looking up to the bridge and the flag deck just below and saw crew members and nuclear experts clapping and cheering. The Captain ordered the crew members who had been on the upper deck to go through the showers. We formed a naked chain, and as we passed through the showers we were greeted by a “Boffin” who waved a Geiger counter wand over us and announced “Clear”

We continued to steam out of the test area and headed across the South China Sea turning to starboard up the Straits of Malacca to be in a position off the coast of Kuala Lumpur on the western side of Malaysia to assist the Army in flushing out Communist Terrorists by bombarding their jungle hideouts, but that is another story, for another time.

A nuclear explosion of this magnitude vaulted Britain into super power status and allowed them to sit at the head table with the other two super powers, the United States of America, and Russia. It changed the course of history, and H.M.S. Cossack was part of that.

 

The following is from Ken Satterthwaite

• On the day of the test we were mustered on the upper deck to witness the explosion. I remember we were just in shorts and sandals and before the actual explosion went off we were told to sit down and cover our eyes with our hands. After the “Mushroom “ we were the ordered down below and closed down to NBCD state 1. Only the Officer of the Watch was on the open bridge and the prewetting party was on the upper deck, all suitably attired. There was no air conditioning and it was stifling below deck.

 

(2) Earlier I mentioned about my little trip to Christmas Island (now Kiritimati), which is part of the ‘Line Islands’ in the Pacific Ocean. I was a young able seaman serving in HMS Cossack and we were assigned to be guard ship for six weeks in November 1957 for one of the nuclear test which Britain was undertaking named ‘Operation Grapple’. It was a bit of a boring routine patrolling looking for unwanted ships around this atoll and when not patrolling we were anchored off the Island which only sported a tented NAFFI canteen, so swimming or fishing was the only other sport. On the due day we steamed off on patrol and all number of foreign flagged ships appeared (No Green Peace), but after trying to chase them out of the exclusion zone we took up our allotted position to watch the explosion. It was an air burst equivalent to 1.8 megatons of TNT (Hydrogen Bomb) what a sight that was. I was sitting on the upper deck along with most of the ships company on a clear sunny day we were ordered to sit down and place our hands over our face, after the explosion we stood up and saw the mushroom rising to the sky it was not only something to behold, but also frightening to think of its destructive power. After this we closed down, rigged prewetting, this was just hoses, as we were a WW2 type destroyer with an open bridge, so there was nothing built in or any air conditioning in the ship, it was stifling. Anyway off we sailed to a nearby island called Fanning (now Tabuaerun) to pick up samples of tests etc., and return them to Christmas Island. After a few more days we set sail for safer climes and a Christmas in Hong Kong. As you can see from my pictures I did not suffer any after effects as some who were based there have reported to have.