Page 195 - Records of Bahrain (1) (i)_Neat

The second GulJ Survey, 1857-1860 185

CHAT. VIII.] liAnREfr* IIARUOUR. 119

trees, and has 4 fathoms close to ; 6 fathoms are about a mile off this
point to the eastward, and 8 fathoms, 4 miles off.
From it, the edge of the shoal runs to southward for 10 miles, to the
south-east point, off which lies a detached patch, least water 2£ fathoms,
the outer edge of which bears N. by E., 6 miles, from Reyah date grove ;
a vessel of light draught might cross this, as it would be a good guide to
her position, with regard to the south-east point of the Ydreru.
From this south-east point the reef takes a south-west direction for 7
miles, to the south point called Jadum : this is on the north side of the
entrance to the Khor al Bab, and from it the reef has an average direction
of N.W. by N. for 9 or 10 miles, as far as the north-west point, and
forms the east side of that passage. The north edge is only approxi­
mately determined.
The Ydrem is chiefly of white sand, or soft white stone ; and on the.
northern edge there are many dark patches of rock on it. It is dry
in parts at low water ; some of the rocks on the north part uncover at
half tide. The whole reef generally shows well, especially with the
sun behind you.
tides*—The tides on the pearl bank, north of the Ydrern shoal, set about
east and west, and influence a ship’s course across the gulf, often considerably.
Along the east side of that shoal, they set north and south, and follow the
bend of the harbour, setting into and out of it; the flood also set's to south­
eastward, between Maharag and Bahrein islands, and to north-westward
through the Khor al Bdb. It sets to the southward, outside Maharag
island. Its velocity in the harbour is from one to two knots. High
water on full and change is at 5^ hours ; rise and fall 7 feet. The amount
of the rise, and the depths of the water, are dependent to a certain extent
on the wiud, whether a north-wester or a south-easter.
directions.—When bound to Bahrein from the northward, (Bd-
shehr, &c.,) if a large vessel, she would have to avoid Rennie shoal*
A departure had best be taken from Jebel Dreng, which should bear
about N.E., in 20 to 30 fathoms water ; from which position, a S.S.W.
course will take her well clear of that shoal, and, according to the tide,
she would strike either theBu Amdmah or Bu Athdmah pearl bank. If
drawing less than 15 feet, she may steer a direct course for these banks
from Bu-shehr outer roads.
If she shoal suddenly from 35 fathoms to 12, and perhaps 6 on the pearl
bank, deepening again when over it to 20 and 25, she has passed over the
eastern or Bu Athdmah bank ; but if she shoal gradually to 20, then
quickly to 9 or 8, afterwards deepening only to 12 or 13, she has struck

* See page 125, least water 17 feet.