In addition, we were encouraged to supply firsthand written reports of events, sightings etc. that may have had marine, ecological/environmental interest.
Clearing boxes in the loft over the weekend I came across the following report sent to the Marine Observer in 1981 which may or may not be of interest!!
"Dear Sir,
Whilst on passage from the Arabian Gulf to Europe on 4th October 1981, the following was observed by the crew on board SS Nordic Clansman (138702 GRT).
Loaded, Crude Oil Draft 67' 09" Speed 7.5 kts
Time: from 0800Z to 1400Z (ship's time = GMT+3)
Posn: @0900Z - 06 59N 52 49E
@1442Z - 06 21N 52 33E
{approx 250 miles SE of the Somalian Coast - rb}
Conditions: Blue skye with 3/8 ***ulus Cloud
Long, moderate SE'ly swell
Calm
Visibility 12+ miles
Air Temp 33C
Sea Temp 28C
Barometer 1013.0
During the above period the sea was flat calm and a metallic grey in colour, broken at frequent intervals by large areas of disturbed and highly agitated water, several of which were brown in colour. Almost all these areas were surrounded by a broad band of brown/white foam. There was a strong smell of seaweed at times.
Whilst encountering these conditions the steering of the ship was seriously affected in all modes of operation. The ship's head fell off by as much as 30 degrees (predominantly to port) and required full, opposite helm to correct the swing. (see enclosed course recorder trace)
{which I don't now have a copy of - rb}
The Gyro and Standard compasses compared favourably at all times. The ATLAS ECHOGRAPH 470 with a maximum depth of 730m gave no indication of a trace at any time throughout the period during which the charted depth of water was 5000m+.
A great deal of marine life was observed at the time including porpoises, swordfish, and schools of whale only one of which came close enough for positive identification. This was a group of some 15 killer whale.
As none of the observers had seen this phenonema before I would be grateful if you could shed some light on what was happening at the time.
Yours sincerely, RB 2/M"
The report was acknowledged and two quite different replies came in - bits of which I quote.
The first was from the Marine Science Branch of the Hydrographic Office at Taunton
"I was interested to receive your letter on disturbed water in the Indian Ocean.......................We are not certain of the cause of this phenonenom, but think it might be due to seismic activity associated with the submarine ridges in the Indian Ocean rather than strictly oceanographic factors; I have written to appropriate authorities for their comments...............................etc"
The second reply came from the Institute of Oceanographic Sciences in Surrey;
"Thank you...............................I think that what they encountered was the northern edge of the strong clockwise eddy which develops in summer between 5 deg N and 10 deg N off that coast. The eddy is generated by the SW monsoon winds, it is typically 500km in diameter, and has surface speeds of up to 7 knots in it's northern and western sectors. To the south and east it's surface currents are generally weaker, only 1 to 3 knots. It has been noticed before in October, running down like a flywheel after the end of the SW monsoon. It's northern boundary can be quite sharp, with a sudden change of current across the boundary. In this case there must have been a change of surface current of at least 4 knots towards ESE, within half the ships length, to deflect the heading by 30 degrees as described. What I find particularly interesting is the evidence of so much marine life there. Nearer the coast, where the Somali current turns offshore in the northwest sector of the eddy, there is strong upwelling bringing high concentrations of nutrients to the surface and consequently high biological productivity, but this did not appear to develop far because the upwelled water was quickly overrun by warmer lighter water from the north. In the present case, it seems possible that large patches of upwelled water may have been carried round in the eddy, perhaps several times, long enough to develop a rich and varied population of marine animals. I would like to know more about it................................I think it's most unlikely to have been a seismic disturbance. Yours.........etc"
I left the Clansman shortly after these replies and don't know how far the conclusions reached or what in fact caused the disturbance but I believe the Marine Observer did include an article on it.
Has anyone else come across that activity in that area before?
Regards
Roger