Invincible Looking Pretty Vincible

The Portsmouth News just reported:

The remains of HMS Invincible are among many national treasures that English Heritage says need better protection.

HMS Invincible was originally a 74-gun French warship, launched in 1744 and captured by the British Navy at the Battle of Finisterre in 1747.

She lies at the sandbanks running along the coast of Portsmouth, after running aground and sinking in 1798.

HMS Invincible is a protected wreck site, but it has now been deemed at risk because monitoring has revealed significant parts of the wreck are becoming exposed due to lowering seabed levels.

Wikipedia says the Invincible wasn’t looking too good when it was captured, as shown above. It was also a more advanced design than any ship in the Royal Navy of the time, so it was very helpful to British ship designers over the next couple of decades.

I didn’t understand how the seabed could be lowering, so I looked for more information on the ship’s present whereabouts. English Heritage says it was discovered relatively recently:

Horse Tail Sand comprises a relatively flat featureless sand bank composed of fine to medium sand with a limited silt component. The wreck was discovered there on the 5 May 1979 by Arthur Mack, a local fisherman, when his fishing nets became caught on an obstruction. Returning to the site with two divers, the site was investigated throughout the summer and various artefacts were raised.

(That last sentence has what we might call a bobbing modifier.)

A wide range of objects have been recovered and only a sample is held by Chatham Historic Dockyard. The remainder were sold at auctions held by Sotheby’s and included sandglasses, leather and wooden buckets, powder barrels and magazine tools, utensils, shovels, brushes, small arms, hand grenades, buttons, rigging and rope.

So it looks like the seabed at that site has been eroding, or lowering, for some time. Thirty-five years ago enough silt had washed away to expose the wreck. And now more of the ship’s remains are being exposed, and possibly damaged. At least that’s my amateur reading. Any commentary from experts in eighteenth-century marine archeology is welcome.