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The ex-Trinity House tender Tavy was sunk on the seabed next to the Breakwater Fort in Plymouth Sound to be used for scientific research.

Type

Trinity House pilot tender

History

At a meeting in May 1995, three members of a Plymouth underwater archaeology group called PMARIG, Jon Greenough, Paul Dart, and Peter Holt, started planning to create an underwater site that could be used for doing experiments in surveying and recording techniques used in underwater archaeology.  The team wanted to sink a timber ship in the sea so the training would be done on a real ship’s hull under realistic conditions. This site would be an asset for training divers in underwater archaeology techniques; it would be an ideal site to carry out research by universities, and it would be used to promote Plymouth as a centre of excellence in this field.

Tavy alongside the Mayflower Steps in Plymouth's Barbican, click the image for a larger version.

The seabed to the north of the Breakwater Fort was already in use by Plymouth Ocean Projects for commercial diver training and already had a collection of structures on the seabed, so it was an ideal location to add one more. The Fort site was sheltered from waves by the Plymouth breakwater, it was easily accessible by divers, it was shallow, and the Fort could be used as a dry and stable base for setting up any electronic equipment needed for the survey work. The original idea was to use the bow section of a decommissioned trawler called Atlantis, but this was very tall and needed a lot of work to make it safe for divers to record. Instead, the team were offered the ex-Trinity House tender Tavy, a clinker-built wooden vessel launched in 1959, and at 7.6m long and with a beam of 1.54m, she was a much more suitable size. Skipper Dave Boon had bought Tavy from Trinity House, and she was later sold to the oil company Conoco as a tender to a fuel barge, but she ended up in the boatyard at J. Boston & Son, and Tavy was donated to the project by Nigel Boston.

Tavy was prepared for sinking between August and October 1995 by volunteers including Kit McAllister, John Spencer, and Jon Parlour, who removed the wheelhouse, any loose objects and anything likely to snag on a diver’s equipment. Fortunately, most of the hard work had been done as the engine and steering gear had already been removed. Permission to sink the vessel was obtained by Nigel Boston and Alan Bax at Plymouth Ocean Projects, so the team were ready to go. Tavy was loaded on the deck of Nigel Boston’s large dive support vessel Terschelling, and she sailed out into the Sound on a calm day on Friday, 23rd December 1995, accompanied by a team of volunteers from PMARIG and a local TV crew. The big dive boat was secured to the fort in the right location, the small timber boat on her deck was prepared for scuttling, and Tavy was lifted over the side. The little wooden ship was loaded up with scrap chain and sinker weights, and she sank to the bottom, sheltered between the two large concrete blocks used for diver inspection tests.

Once on the seabed, Tavy was recorded by divers using several different methods, including tape trilateration, acoustic trilateration using a Sonardyne Homer Pro instrument, underwater acoustic positioning using a Sonardyne LBL diver tracking system, and 3D photogrammetry using an early software program for processing called PhotoModeler.  The results of the surveys were compared to find out the strengths and weaknesses of each method.  The little ship was also monitored to see how the hull and its environment changed over time. The ship stayed in one piece for a few years, but later the stern deck was damaged. It has been suggested that a boat had tied a rope to the vessel and tore away the deck, so accelerating the collapse of the hull.  By 2003, the remains of the hull were a collection of flattened timbers held down by the chains and weights originally used to sink her.

Location and Access

Site plan of the Breakwater Fort structures by The SHIPS Project, click the image for a larger version.

Plymouth Breakwater Fort, north side.

What remains of Tavy still lies between Blocks 1 and 2 northeast of the Breakwater Fort, partly buried in the seabed.

.Nearby wrecks include the FS Poulmic , the Fylrix , Yvonne and Vectis

Last updated 18 July 2025

Position GPS: 50° 19.920 N 004° 08.526 W
Depth: 12m

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