Thorness Bay is located off the south coast of England within the Western Solent and on the northwest shore of the Isle of Wight. It is an anchorage in a long open bay that is backed by a low-lying rural valley.

The shallow bay forces vessels well out into the western Solent, making this an exposed anchorage that is subject to the full run of the Solent's tidal streams. Access is straightforward at all stages of the tide, day or night.

This berth will be extremely tide-ride.

Keyfacts for Thorness Bay

Position and approaches

Haven position

50° 44.570' N, 001° 21.780' W

This is about 200 metres of the yellow spherical racing buoy Fl.Y.4s in about two metres.

What is the initial fix?

This is over the 10-metre contour, about 300 metres from the yellow spherical racing buoy Fl.Y.4s, which makes an ideal sea mark for the approach.

What are the key points of the approach?

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What's the story here?

Thorness Bay is a long, open bay with a sand and pebble beach backed by low, broken cliffs, forestry, and rolling farmland. It lies between the offshore ledges of Salt Mead Ledges and Gurnard Head. Inshore, a low valley floor connects to its cliffs, rising up into the rolling farmlands of Calbourne.




Thorness Bay has a ledge that extends up to 800 metres from its shoreline, with less than a metre over it, and then it steps down abruptly to 18 metres. Consequently, it is not great and more the domain of a shallow draft vessel.




The best anchoring for deeper draft vessels is to be found west of the bay itself, under where the eastern end of Burnt Wood comes down to shore. Here, about 600 metres out from the shoreline and 300 metres inside the seasonal spherical buoy, there is a 150 metres wide contour with depths ranging from 2.6 metres to 1.5 metres LAT.

How to get in?

Thorness Bay presents as a long, open bay on the north-west coast of the Isle of Wight, stretching about two miles between Salt Mead Ledge to the west and Gurnard Head to the east. The shoreline is characterised by a sand and pebble beach backed by low, broken cliffs, with a low-lying valley floor inland that rises into rolling farmland. The bay is bordered by woodland and farmland, giving it a rural and undeveloped appearance from the water. Refer to Western Approaches to the Solent for appropriate navigational guidance.




Vessels approaching from the west should keep outside or close inside the Salt Mead starboard hand buoy Fl(3)G 10s. This buoy marks the drying Salt Mead ledge that extends 500 metres offshore and is inclined towards Cowes. The outer end of the ledge terminates about midway between the buoy and the shore, and its foot is located where the western end of the Burnt Wood tree plantation comes down to the beach. It is principally a concern for those cutting inshore to the anchorage or making the best of an adverse tide.



Vessels approaching from the east should keep outside the green starboard hand Gurnard Ledge Light-buoy. This is moored 200 metres to the northwest side of the Gurnard Ledge that dries in parts at LAT.




Stay well off Gurnard Head as the drying Quarry Ledge, or Baxter's Ledge as it is called locally, extends out 250 metres from its foot. An orange ball, Baxters, is laid off the ledge's western end during the summer season.

Locate the seasonal spherical racing buoy, Fl. Y.4s that provides a conspicuous mark for the anchoring position.




From the initial fix, set on the 10 metre contour, start to sound in a south-eastward direction for about 100 metres. A wooden post seen on the shore amidst a bank of rocks that make up a rocky ledge makes a good mark to steer onto. This post is on the edge of the LAT drying area and marked on the charts as a sewer outfall, but it is now disused.




Anchor according to draft, with the 2-meter area located approximately midway between the spherical racing buoy and the outfall post. Shallower draft vessels will find 1.1 metres CD 300 metres west by northwest of the post.



There is good holding in clay once the anchor has been well dug in. Land on the beach by tender.

Why visit here?

Thorness Bay derives its name from thorn and ness, the former meaning of a 'thorny bush' with ness meaning headland or promontory; 'thorny headland'. Fronted by a beach, this small, low-lying valley is largely undeveloped and little disturbed, but steeped in geological and historic interest.




The bay is significant in the Tertiary period palaeobotany. From Thorness to Gurnard, the cliffs rise to 45 metres and comprise clays and marls of the Bouldnor Formation, overlying Bembridge limestone at beach level. These limestones outcrop as foreshore reefs to form the protective shallows off Thorness Bay and the Gurnard Ledge. Erosion created rock exposures in the intertidal zone, in outcrops at the base of the slipped cliffs and in landslip scars above the beach. The richest of the bay's exposures are to be found in the Bembridge Limestone and Bembridge Marls, and near the base of the latter, there is a thin limestone known as Insect Limestone. This layer provided fossils of insects and plants that have led to the discovery of more than 250 new species, including tree ants and termites. It also contains unique flora of fossilised plants that belong to over 120 different species, of which 20 are unique to this site. Unlike most other fossilised specimens, the bay's Insect Limestone preserves the fossilised plants so well that it enables outstanding recognition of plant organs.



Thorness Bay has also been recognised as highly archaeological, with post-alignments, hurdles, and other wooden structures of radiocarbon dating to the late Bronze Age, Iron Age, Roman and post-medieval periods. The intertidal zone of Thorness Bay has been a treasure trove for historians looking for evidence of early human inhabitation. Numerous flint and stone implements from the Mesolithic and Neolithic periods have been discovered here, along with further concentrations around Saltmead and Gurnard Cliffs. Roman material, including pottery and building material, has been recovered from the eroding cliffs, and what is believed to be a Roman pottery kiln was found at Burnt Wood along with a Bronze Age cremation. Two sites with midden deposits, ancient refuse dumps of Roman and Medieval date, have been recorded, with one containing examples of medieval pottery shards.




One historic feature remains visible on the beach today at low tide. This is the remains of the World War II Solo pipe manifold that ran across the seabed from Lepe to Thorness Bay. It was used to supply the Isle of Wight with fuel, and later, when the Allied forces landed in Normandy, PLUTO, or Pipeline Under The Ocean, went under the English Channel to carry fuel to the French coast and beyond.




The bay is now part of the designated Heritage Coast and lies within the Isle of Wight Area of Outstanding Natural Beauty. The site was notified as a site of Special Scientific Interest in 1966 for both its biological and geological features. Thorness Bay is an essential component of the Solent estuarine system and an internationally important site for overwintering wildfowl and waders. Its shores and marshes also provide substantial feeding and roosting grounds for significant numbers of waterfowl. So much so that it has also been proposed that it should be designated under the Ramsar Convention of Wetlands of International Importance, as a Special Protection Area for the Conservation of Wild Birds.




Today, the bay experienced by visiting boaters will be that of a quiet pastoral valley. Despite having Thorness Bay Caravan Park, one of the Island's major holiday camps, above in the forest, it retains a peaceful, remote character. This is mainly because the only vehicle access is through the holiday park. Public access is via a single footpath leading to the beach or people finding their way from the Coastal Path that skirts the bay. The beach never gets overwhelmed by visitors, and those that come are primarily made up of walkers, anglers, and a scattering of beach goers who bring a little intrest, colour and noise. Still, the general feeling is one of agriculture and a peaceful woodland backwater.




From a boating perspective, this is not the best anchorage by any means. The limestone ledges fronting the bay push anchoring vessels out three-quarters of a mile from the beach. This leaves a vessel severely tide rode in the Solent tidal streams, so it needs to be a settled time for an overnight stay. Likewise, Thorness Bay's beach is not particularly appealing. It features a line of sand, probably ten metres wide, beneath which it slowly fades into shingle and then rocks at low tide. Although the inshore area consists of rolling farmland, the Fawley Oil Refinery industrial complex is prominent in the views across the Solent to the mainland.




However, this is the first beach available for a vessel with a berth in the Southampton Waters area. It is also very sheltered from the prevailing winds, and there is plenty of boating action in the western Solent to watch go by. Once ashore, the disadvantageous ledge provides a shallow, safe bathing area that is several degrees warmer on a sunny day and forms a lagoon at high tide along the shore, making it ideal for a family boat. Moreover, young, or indeed not so young, palaeobotanists can land on the tiny private beaches found at the foot of Burnt Wood to discover Thorness Bay’s marls, which are full of unique fossilised specimens from the Tertiary period.

What facilities are available?

There are no facilities in Thorness Bay. All facilities may be found in Cowes, three miles eastward.

Any security concerns?

Never an issue known to have occurred to a vessel anchored of this remote location.

With thanks to:

Michael Harpur Sailing Yacht Whistler.