Gravel for sale
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 Study of a dredger, c. 1672. © NMM |
Elizabeth I issued a new charter in 1594, granting Trinity House the sole rights of ballastage in the River Thames. This had previously been the preserve of the Lord High Admirals. This meant that the Corporation could dredge up gravel from the river bed for sale as ballast to unladen sailing ships.
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| A dredger moored off Greenwich Hospital. © NMM | Dredging took place to keep the river navigable for ocean-going ships. The waste that was left behind from this dredging was a profitable sideline since all vessels in the Thames had to obtain their shingle and gravel from the ballast owners.
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| Plan of the Crescent's ballast, Deptford, 6 May 1799. © NMM |
This diagram of the warship HMS Crescent (1784) gives an idea as to how ballast was distributed around a sailing vessel to keep it stable.
At the height of the trade, in 1804, the Corporation employed nearly 250 men in the work of ballasting ships. With the passing of sail in the mid-19th century, ballastage began to die out because steamers used water as ballast.
Keeper of seamarks
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| Captain Bullock's safety beacon erected on Goodwin Sands, September 1840. © NMM | The 1594 charter also recognised Trinity House as the keeper of all British seamarks. These included buoys and land-based beacons, such as steeples, woods and other marks visible from the sea.
The Corporation was allowed to fine anyone up to £100 for removing any of these land-based seamarks without the Trinity House Elders' permission. If the guilty person was not worth that amount, he could be convicted of 'outlawry'.
Until lighthouses became widespread, landmarks were vital navigational aids. This picture shows a mark being erected by Trinity House's Captain Bullock on Goodwin Sands, a notorious stretch of coast in the Thames Estuary.
Buoys
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| Buoys used by Trinity House. © NMM | Buoys are floating seamarks used to indicate:
- channels through sandbanks and shoals in estuaries
- the approaches to a port where shore marks are too distant for sailors to see
- wrecks and other dangers to ships.
This image shows the variety of buoys used by Trinity House in the 19th century.
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| Buoys at the National Maritime Museum main gate. © NMM |
Most buoys have two main colours, black and red, either used plain or with white. There are also green wreck buoys.
Sometimes they have flashing lights or bells that ring with the movement of the waves and serve to warn approaching ships. The buoys vary in size and are usually conical, cylindrical or spherical in shape. These two examples are currently on display at the entrance to the National Maritime Museum.
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| Repairing a Trinity House buoy. © NMM |
In this photograph, two Trinity House workers are repairing a buoy that has been winched on board the Trinity House vessel Hanton.
From 1 April 1993, following the Ports Act, the management of lights, buoys and beacons needed for local navigation was transferred from Trinity House to local harbour authorities.
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