Hourly tidal streams, West Solent area (NP337)

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TIDAL STREAMS ST ALBANS HEAD

TIDAL STREAMS – About three-quarters of a mile offshore southward of Lulworth cove the east-going stream, spring rate 1.6 knots, begins -0150 Devonport (+0455 Dover); the west-going stream, spring rate 1.7 knots, begins +0410 Devonport (-0130 Dover).

About 1¼ miles southward of St. Alban’s head the east-going stream, direction 120°, begins -0100 Devonport (+0545 Dover); the west-going stream, direction 275° to 290°, begins +0525 Devonport (-0015 Dover); greatest rate in both directions 4.5 to 4.8 knots.

Eddies, similar to those off Portland peninsula (see Portland Tidal streams), form off St. Alban’s head, but the head is less prominent than the bill so the eddies are smaller; further, on account of the shape of the coast, only the eddy on the western side is of any importance.  Anyway, along the western side of the head the stream runs nearly continuously south-eastward, and a race, which may be violent and may extend as much as 2½ miles seaward, when both stream and wind are strong and their directions opposite, forms off the head.  The position of the race varies with the direction of the stream, and moves eastward with the east-going stream, westward with the west-going stream.
 
TIDAL STREAMS NEEDLES CHANNEL

TIDAL STREAMS – The streams run about north-eastward and south-westward, in the direction of the channel and attain their greatest rates between Hurst point and Albert fort, where, in about mid-channel, the north-east-going stream begins +0450 Portsmouth (+0505 Dover), and attains its greatest rate, 3.9 knots at springs, 1.9 knots at neaps, -0500 Portsmouth (-0445 Dover); the south-west-going stream begins -0110 Portsmouth (-0055 Dover), and attains its greatest rate, 4.5 knots at springs, 2.2 knots at neaps, +0230 Portsmouth (+0245 Dover).

On the western side of the channel a set may be experienced, away from or towards the Shingles according to the direction of the stream; there are overfalls on the south-eastern edge of the Shingles during the north-east-going stream.  At the southern end of the channel the streams run strongly across the Bridge.

The north-east-going stream runs strongly on the Isle of Wight side of the channel, and round Alum, Totland and Colwell bays; there is little stream in these bays during the south-west-going stream.

The North channel and Needles streams meet and separate south-eastward and southward of Hurst point, where there may be turbulence when the streams are strong, especially during the north-east going stream.  During the south-west-going stream an eddy runs strongly eastward near the land southward of Hurst point.


TIDAL STREAMS NORTH CHANNEL

TIDAL STREAMS – In the western approach to North channel, at a position in about 3½ miles 279° from Hurst Point low lighthouse, the east-going stream mean direction 092°, spring rate one knot neap rate 0.5 knot, begins +0445 Portsmouth (+0500 Dover); the west-going stream, mean direction 269°, spring rate one knot neap rate 0.5 knot, begins -0115 Portsmouth (-0100 Dover).

In the channel the streams are strong and run in about the direction of the channel.  At a position half a mile 254° from Hurst Point low lighthouse the east-going stream, spring rate 3.4 knots neap rate 1.7 knots, begins +0445 Portsmouth (+0500 Dover); the west-going stream, spring rate 3.5 knots neap rate 1.7 knots, begins -0115 Portsmouth (-0100 Dover).  The streams gain and lose strength very quickly; the rate of the east-going stream is 3 knots, or more at springs from about +0610 till -0300 Portsmouth (-0600 till -0245 Dover); the rate of the west-going stream is 3 knots or more at springs from about -0030 till +0330 Portsmouth (-0015 till +0345 Dover).

A strong eddy runs eastward along the land southward of Hurst point, and there are ripples on the northern edge of the Shingles, during the west-going stream.


TIDAL STREAMS HURST ROAD

TIDAL STREAMS – From off Hurst point to about a line Stansore point to Egypt point the streams run in about the direction of the channel.  The times at which they begin vary very slightly in different parts of the channel, and, at a position 0.9 mile 342° from Egypt point, the east-going stream, spring rate 2.1 knots, neap rate 1.1 knots, begins +0445 Portsmouth (+0500 Dover); the west-going stream, spring rate 2.6 knots, neap rate 1.3 knots, begins -0110 Portsmouth (-0055 Dover).

The west-going stream is stronger than the east-going stream everywhere in the Western Solent, but the rates differ considerably in different parts of the channel; thus, near mid-channel off Lymington banks the spring rate of the east-going stream is 2.2 knots, and of the west-going stream 2.5 knots, the corresponding rates between Solent banks and Salt Mead ledges are 3.0 and 3.2 knots, and off Lepe Middle 3.4 and 3.5 knots, respectively.

The streams near the land or shoals at the sides of the channel do not differ appreciably from those in mid-channel; thus off Yarmouth the streams run in about the direction of the coast; the east-going stream, spring rate 2.4 knots, neap rate 1.2 knots, begins +0450 Portsmouth (+0505 Dover); the west-going stream, spring rate 2.8 knots neap rate 1.4 knots, begins -0115 Portsmouth (-0100 Dover).

Eastward of the Stansore point to Egypt point line the east-going stream divides and runs eastward towards Spithead and the Eastern Solent, and north-eastward towards Southampton water.  The streams from these directions meet eastward of the line, and continue westward in the Western Solent.
 
TIDAL STREAMS CAUTIONS BACK OF THE WIGHT

DIRECTIONS – Between the Needles and St. Catherine’s point the coast must be approached with caution, particularly during the east-going stream which, in the offing, sets inshore towards the many ledges extending from the coast, of which the most dangerous are those off Brook and Atherfield points.  The highest of the chalk cliffs on the eastern side of Freshwater bay in line with Brook point, bearing 315°, leads south-westward of Atherfield ledges and all dangers south-eastward of them.

At night, a vessel from the westward should keep in the white sector of the Needles light bearing more than 300°, when rounding St. Catherine’s point (Lat. 50° 34’ N., LONG. 1° 18’ W.) and should take care not to approach within one mile of the land.
 
TIDAL STREAMS FRESHWATER BAY AREA

TIDAL STREAMS – At a position about 4.6 miles 205° from Needles lighthouse, the stream is nearly rectilinear.  The east-going stream begins, in a direction about 040°, +0530 Portsmouth (+0545 Dover), but changes very quickly to about 080°, and attains its greatest rate, 2.1 knots at springs, one knot at neaps, in a direction 085° (directly towards Atherfield ledges), - 0330 Portsmouth (-0315 Dover).  The west-going stream, spring rate 2.2 knots, neap rate 1.1 knots, runs in a mean direction 265° and begins -0030 Portsmouth (-0015 Dover).

Farther eastward there is no set towards the land.  At a position about 6.8 miles 146° from Needles lighthouse, the stream is nearly rectilinear.  The east-going stream, spring rate 2.7 knots, neap rate 1.3 knots, mean direction 100°, begins +0500 Portsmouth (+0515 Dover); the west-going stream, spring rate 2.3 knots, neap rate 1.2 knots, mean direction 285°, begins -0120 Portsmouth (-0105 Dover).

In Freshwater bay the stream is weak close inshore, but gains strength eastward.  In the middle of the bay, at a position about 3 miles 101° from Needles lighthouse, the east-going stream, spring rate one knot, neap rate 0.5 knot, mean direction 110° (directly towards Brook ledges), begins +0445 Portsmouth (+0500 Dover); the west-going stream, spring rate 1.1 knots, neap rate 0.6 knot, mean direction 290° (towards the land eastward of Needles point), begins -0130 Portsmouth (-0115 Dover).
 
 

TIDAL STREAMS ST CATHERINES

TIDAL STREAMS – The coastal streams are not strong off Brook point, but the east-going stream, which runs across Brook ledges, increases eastward and runs strongly across Atherfield ledges and Chale rock; the west-going stream also runs across the rock and ledges, but less strongly.

At a position about one mile south-westward of Atherfield point,  the east-going stream, spring rate 1.8 knots, neap rate 0.9 knot, mean direction 125° (towards St. Catherine’s point), begins +0420 Portsmouth (+0435 Dover); the west-going stream, spring rate 2.2 knots, neap rate 1.1 knots, mean direction 300°, begins -0130 Portsmouth (-0115 Dover).

The set of the east-going offshore stream towards the south-western coast of the Isle of Wight, and of the east-going inshore stream across the dangers between Brook point and St. Catherine’s point, must not be forgotten.

At a position about 1¼ miles 143° from St. Catherine’s Point light-house, the east-going stream, spring rate 3.7 knots, neap rate 1.8 knots, mean direction 075°, begins +0520 Portsmouth (+0535 Dover); the west-going stream, spring rate 3.8 knots, neap rate 1.9 knots, mean direction 257°, begins -0055 Portsmouth (-0040 Dover).

A race occurs off St. Catherine’s point, and may be violent when the stream is strong and a strong wind is blowing in the opposite direction; the race is specially violent south-eastward of the point in westerly gales at springs, during the west-going stream.  Eddies occur near the land westward of the point during the west-going stream.


 
 
Adapted from Admiralty Sailing Directions English Channel 1947

Article Info

Author:
VisitMyHarbour
Category:
Tidal Streams
Added:
02/11/2012
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