Her holds were crammed with weapons to fight the Spaniards, but in the end they did little but drag the ship to the bottom of the sea.

Archeologists have unveiled findings from the most complete wreck of a Tudor warship to be excavated since the Mary Rose was raised to the surface 25 years ago.

The ship sank, probably in 1592, in reef-strewn waters off the Channel Island of Alderney. It was carrying an arms shipment to English soldiers in France, the remains of which are now giving archeologists an unparalleled insight into England’s military power just four years after it defeated the Spanish armada.

Artefacts so far recovered include six cannons, armour, muskets, swords and even ceramic hand grenades designed to spray victims with flaming tar. But they represent only a fraction of the thousands of items still on the seabed.

The organisers of the excavation will next month launch an appeal to raise £150,000 for the next phase of the excavation and to explore whether the ship can be raised intact.

They say much of the wreck lies under deep layers of sand, which are preserving it. They have found the oak rudder largely intact, and say this raises the possibility that much of the buried ship remains.

“This is one of the grandest and most exciting periods of our naval history but until now we have not had an example in English waters that has been properly looked at by professional archeologists,” said Mensun Bound, a marine archeologist and fellow of St Peter’s College, Oxford, who is directing the excavation of the Alderney wreck.

“We have raised the rudder from the ship, which is made of oak and we hope, like the Mary Rose, that some of the structure of the ship may remain under the sand and that we can excavate and eventually raise it.”

Although the wreck was first located in 1977 by crab fishermen, archeologists have said little since then about the extent of the excavations, mainly because of concerns that unscrupulous divers would loot it.

Sir Norman Browse, president of Alderney, whose government owns the wreck, said: “Until this summer we have deliberately kept our discoveries quiet, but now we require major funding for equipment and conservation and so have been forced to go public.”

The disclosure coincides with the announcement on Friday by American deep-sea explorers that they have recovered a 17-ton hoard of gold and silver coins, potentially worth £250m, from a 17th-century shipwreck off Cornwall. It is thought the salvage company, Odyssey Marine Exploration, has found the Merchant Royal, a ship returning to Dartmouth from Mexico laden with treasure when it sank near the Isles of Scilly.

The name of the Alderney ship is not known, but is only the second substantial Tudor wreck to have been discovered near Britain. The other is the Mary Rose, now on display in Portsmouth, which foundered in 1545 as Henry VIII watched it leading his fleet out of Portsmouth to attack French ships in the Channel.

The ship found off Alderney was built some 40 years later and the discoveries show it was far ahead in terms of military technology. The archeologists believe the ship weighed up to 300 tons, less than half the weight of the 700-ton Mary Rose.

Its date has been pinpointed by a combination of studying timber and items on board together with a key document from the era, which has survived by chance. Growth rings on wood from the hull show it was cut from oak trees growing in southern England until about the 1580s. Two lead weights with the monogram of Elizabeth I, recovered from the wreck, date from no earlier than 1588.

A letter found in the National Archives in Kew, southwest London, and dated November 29, 1592, suggest the ship may have been a vessel sent by Lord Burghley, Elizabeth I’s chief minister, on a secret mission to forces in France. Soldiers were stationed in Brittany to forestall any attempt by Spain to seize a deepwater port in France as a base for invading England and avenging the armada’s defeat.

The letter was sent to Burghley by Sir John Norreys, commander of the Brittany expedition. It reads: “I have yet heard nothing but that the two packets sent from your lordship are lost in a ship that was cast away about Alderney.”

David Loades, honorary research professor at Sheffield University and author of several Tudor naval histories, said: “The chances are it was a privately owned warship taken up by the government. If it was in fighting trim there would have been over 100 men on board.”

The ship is now resting in a sandbank half a mile off the northern coast of Alderney, 100ft below sea level. It may have been sunk by a combination of winter storms, strong currents and reefs.

So far more than 1,500 artefacts have been discovered but Bound estimates this is only 5% of the total. A more thorough search may, in addition to the hull, uncover the bones of sailors trapped in the wreck.

The strong currents sweeping over the sandbank, however, make work difficult for anyone diving down to the wreck. Parts of the ship that are exposed one day can be buried under 15ft of sand the next.

Divers, who can only work for up to 30 minutes at a time over six-week periods in the summer, use vacuum cleaners to suck up sand and expose artefacts. The archeologists hope the extra funds will provide more divers and boats to search the site. Bound will also use a dinner hosted by the Duke of York, who has been made patron of the wreck, to encourage donations.

Many finds give an insight into how the Elizabethans lived at sea. They include a comb made of bone and a pewter bowl scratched with a name. In addition to the grenades found on board other innovative weapons include “expanding shot”, linked metal bars that would be fired from a cannon.

Loades said: “The Alderney wreck is unique for this period. I do not know of any other English ship for which there are any remains from this period at all.”

More on the excavation, www.alderneywreck.com

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