Thorney Marina set at the head of arm of Chichester Harbour, which is situated on the south coast of England. It is a small rural marina on the north shores of the harbour.

Set deep within the estuaries’ channels it offers good protection in most all conditions. Although the harbour is entered over a moderately deep sand bar, and between sand banks, it is very well marked and straightforward. The final channel to the marina however entirely dries. It can only be entered with a sufficient rise and with the benefit of daylight to navigate its unlit but well-marked approaches.

This is a very shallow marina that is only accessible by shallow draft vessels at the top of the tide.

Keyfacts for Thornham Marina

Position and approaches

Haven position

50° 50.205' N, 000° 54.937' W

This is the head of the northeast most pontoon where the approach channel meets the marina.

What are the key points of the approach?

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How to get in?

Thornham Marina is a small rural marina and boatyard located on the northeast side of Thorney Island and the northern shore of Chichester Harbour. It is accessed via the Thorny Channel that leads to Prinsted Channel and the marina lies at the head of the latter. The Prinsted Channel and marina are only accessible on a rise as they both dry at half-tide. Thorney Channel is itself accessed from Chichester Channel that is detailed, along with approaches to Chichester Harbour, in the Itchenor entry.





Thornham Marina is a small 78 berth marina that entirely dries at 3.2 metres. It has some additional berths within a gated basin that maintain a depth of 1.75 metres. As such the marina can only ideally cater for catamarans or vessels of 10 metres in length that draw 1.5 metres or less and can take to the mud. It is ideally addressed by deeper draft vessels in the range about one hour either side of High Water Springs. Been somewhat removed and challenged by its shallow waters Thornham Marina has no dedicated visitor berths but accommodates visitors if it has space. In all cases it is best for newcomers to make contact with the marina office on P: +44 1243 375 335, VHF Ch. 80 Call Sign [Thornham Marina] and take advice.





The Thorney Channel is entered from the Chichester Channel close west of the Camber Light-beacon south cardinal pile, Q (6) + LFl 15s, that stands 500 metres southeast of Pilsey Island. When close the Camber Light-beacon the substantial piles within the channel make the fairway plain. The first port ‘Pilsey’ pile off Pilsey Island and a corresponding starboard pole on the opposite bank will be clearly seen 300 metres north by northwest. Pass between these marks and continue north up the deep, steep-to Thorney Channel passing along the eastern shore of Pilsey Island.




About 500 metres northward of the Pilsey pile is another substantive port-hand beacon, Fl [2] R 10s, and the corresponding ‘Thorney’ starboard-hand beacon, Fl G 5s, that mark a gap between broken piles east of Longmere Point, Thorney Island’s south-eastern most point. Pass between the marks and continue past Thorney Island Sailing Club and the small island church located ¾ of a mile to the north.


Follow the line of moorings, with port and starboard marks on the banks, north along the east side of Thorney Island, where after ½ a mile it divides into the Prinsted and Nutbourne Channels, both of which dry.


Entering Prinsted Bay continue northward along the island shoreline using the marina markers. At the last set of marks, turn hard to port and the marina is immediately ahead.




Berth as directed by the marina office.

Why visit here?

Thorney Island got its name from its profusion of Hawthorn bushes. Recorded as Thornei in the Doomsday book of 1086 and in the 11th Century as Thorneg, its name is made up of thorn and èg, meaning ‘thorn-tree island’. Thornham, is likewise derived from thorn and hám that means the ‘homestead or village where the thorn tree grows’.




Most unusually both Thorney Island, and Pilsey Island immediately south, are not technically islands anymore. Maps as late 1835 show Thorney and Pilsey islands detached from the mainland but this was soon to change. Thorney became part of the mainland in 1870 when an embankment was built along its western side that linked it to what is now Emsworth Yacht Harbour. This ambitions task succeeded in reclaimed 72 hectares of tidal mudflats and narrow channels that once separated the island from the mainland. The area known as the ‘Great Deep’ was thereafter regulated to overflow into the harbour via sluice gates. A later higher embankment was added on to the remnants of the old wall. In the last several decades nature has likewise connected Pilsey Island. Sand has been naturally deposited between it and Thorney Island creating a causeway or bridge. This linking of the islands has created what is more appropriately described as peninsula that juts out into Chichester Harbour.


The area to the south of the Great Deep is owned by the Ministry of Defence and the island had an important RAF airfield here from 1938. The base housed fighter aircraft that were involved in the Battle of Britain during which the base itself came attack from the Luftwaffe. The wartime airfield consisted of three concrete runways, laid in 1942, plus aircraft hangars and it was protected by gun emplacements, pill boxes and anti-tank traps. RAF Thorney was used by 236 Squadron of 11 Group which was the most heavily engaged group in the Battle Of Britain. At its height the base had permanent accommodation for 3,636 male and 508 female personnel. In the latter stages of the war the base was transferred to RAF Coastal Command for the protection of shipping along with other various roles. The role of the airfield continued until 1976 when, after a brief period as a temporary home for Vietnamese refugees, it was taken over by the Royal Artillery. They re-opened the site in 1982 and is now the base of an Artillery Regiment known as the Baker Army Barracks.


At least 32 aircraft came down in the harbour area during World War II, 13 of them in 1940. This does not include crashes and other aircraft losses at RAF Thorney. Many of the airmen who lost their lives here during this time now lie in the well-kept churchyard of Thorney Island’s church. The church is dedicated to St. Nicholas, the mariner's saint, and in its small cemetery the RAF graves lie alongside the graves of Germans in one of the most attractive and peaceful areas of the island.


St. Nicholas is situated in the old village of West Thorney village that is incorporated into a British Army military base. It oddly lies on the east coast of the island and was name so to distinguish it from East Thorney in Selsey. The church dates mostly from the late twelfth century but was enlarged in the thirteenth into a full- sized church of chancel, nave, aisles, and west tower. It has Norman windows in the chancel, and a tie-beam and kingpost roof. Why it was built in such an isolated position is a mystery. It was described by AA Evans, in the Chichester Diocesan Gazette, as the ‘loneliest, remotest, last seen, least known and altogether utmost church in Sussex’. Despite its age there are a number of modern touches including an engraved window and a well-designed modern example of a simple pulpit faced with sculpted slate slabs. It is still used by local parishioners and those that are prepared to walk to it via the lengthy footpath.




The island area comprises a mixture of open grassland, scrub and reed beds. This variety of habitat, in conjunction with the surrounding wetlands, makes Thorney Island one of the best MOD sites for ornithology, with species including Brent Geese, Oystercatchers, Lapwings, Curlews, Skylarks and Shelduck. The Deeps now form an important roost and gathering area for harbour birds and this raised embankment makes a good bird watching point. Pilsey Island is a nature reserve that the Royal Society for the Protection of Birds has managed since 1985, from the MOD. The WWII structures pillboxes are in differing conditions and the anti-tank defences being in poor condition.




All this can be taken in via circular walk of about 8 miles around the perimeter of Thorney Island. The walk that takes in Thornham Marina and Emsworth circles the island providing splendid views over the harbour. South of the Great Deep public access to the island is strictly limited to the footpath that runs around the foreshore as part of the Sussex Border Path. The island remains a military base and access is controlled by ‘signing in’ via an intercom at the security gates which are remotely controlled by the guardroom. Thereafter the footpath is monitored at all times and you cannot take any short-cut across Thorney Island. Public access is strictly limited to the coastal path and the church of St Nicholas. It is possible to walk either way around the island, as both directions offer interesting and varied perspectives. The path is clearly waymarked by the sign of a curlew.

What facilities are available?

The pontoons provide power and water plus a new private shower and toilet cubicle. The marina has a state of the art fully submersible lift capable of lifting 12 tonnes and a Merlo telescopic forklift for stepping/un-stepping masts. Winter storage is also available. They offer hardstanding for 300 boats. Fin keeled boats are primarily stored using cradles that may be hired from the marina office. The surrounding shipyard has a host of small workshops that provide a wide range of onshore facilities including engineering, sail and canvas repair.

The charming medieval town of Emsworths, about a mile away, has most all facilities. Emsworth railway station is on the West Coastway Line. It has services that run to Portsmouth, Southampton, Brighton and London Victoria. Stagecoach operate the number 700 bus which operates between Brighton and Southsea. Local bus services are provided by Emsworth & District, which operate services to Havant and Chichester.

Any security concerns?

Never an issue known to have occurred to a vessel in Thornham Marina.

With thanks to:

Phil Walker Deputy Harbour Master Chichester Harbour.