HMS Gleaner (H86): The Smallest Ship in the Royal Navy

A Very Small Ship With a Very Long Career

HMS Gleaner was, by the time she finally retired, the smallest commissioned vessel in the entire Royal Navy, measuring just under 15 metres in length, displacing a mere 22 tonnes, and crewed by a modest complement of eight or nine sailors: two officers, one senior rating and a handful of junior ratings. For a ship that size to still be worth building at all says a great deal about how much unglamorous, precise work the job of an inshore surveyor actually demands.

The 'HMSML' designation she carried, Her Majesty's Survey Motor Launch, rather undersells quite how much notably useful work such a small hull managed to pack into a career spanning 35 years.

HMS Gleaner was launched on 18 October 1983 and commissioned some seven weeks later on 5 December 1983 as an inshore survey vessel, originally intended for hydrographic work along the south coast of England.

She was fitted out for exactly the kind of unglamorous, meticulous data-gathering that keeps larger and more famous ships safely off the rocks: multibeam and sidescan sonar, Applanix POS MV georeferencing equipment, C-NAV GPS and Kongsberg echo sounders, all packed into a hull with a top speed of a remarkably unhurried 14 knots.

That equipment list is worth translating, because one item on it is the reason a 22-tonne launch could do serious hydrography at all. Multibeam and sidescan sonar tell you the shape of the seabed, and how a swath survey works is explained in the article on HMS Echo (H87). The Applanix POS MV is the awkward part. A sonar beam fired from a moving hull only means something if you know precisely where that hull was, and which way it was pointing, at the instant the beam left it, and a fifteen-metre boat in a Channel chop is pitching, rolling, heaving and yawing continuously. The POS MV measures all of that hundreds of times a second and marries it to satellite positions, so that every ping can be put on the chart where it actually belongs rather than where the boat happened to be lurching. Take that box out and Gleaner is a rowing boat with an echo sounder. Put it in and she is a survey ship.

The other question, why the Royal Navy bothers with anything this small, has a straightforward answer: the dangerous water is the shallow water, and a big ship cannot go there. Harbour entrances, dredged channels, the narrow bits with rocks in them and the ground immediately in front of a naval base are precisely where a grounding is expensive and precisely where a deep-draught survey ship dare not steam. The same logic put an Inshore Survey Squadron on the East Coast for a quarter of a century, as described in the article on HMS Enterprise (A71). Gleaner was the last, and by some distance the smallest, of that tradition.

Charting Britain's Waters, and a Trip to Switzerland

HMS Gleaner spent the bulk of her career surveying around Britain's coastline and European ports, work that rarely made headlines but properly mattered to the safe navigation of everything from fishing boats to aircraft carriers. Her operations eventually extended well beyond the south coast for which she was originally intended, taking in the Netherlands and the Channel Islands.

Her most unusual outing, however, came in 1988, when HMS Gleaner travelled up the Rhine all the way to Basel, becoming one of a select handful of Royal Navy vessels ever to visit landlocked Switzerland, a truly eyebrow-raising achievement for a ship whose day job was normally measured in nautical miles off the English coast rather than river miles through continental Europe.

Charting the Way for a Carrier

HMS Gleaner's most consequential work came late in her career, in 2016, when she undertook a comprehensive survey of the Firth of Forth, carefully measuring bridge heights and channel depths ahead of HMS Queen Elizabeth's planned departure down the river from Rosyth, where the new aircraft carrier had been built.

The reason those bridge heights mattered is one of the better pieces of naval arithmetic. Queen Elizabeth was built at Rosyth, which is upstream of three bridges, and she is 65,000 tonnes with a masthead something over sixty metres above the water. She could only get out of the basin at Rosyth at high water, with inches to spare on either beam, and she could only get under the Forth Bridge at low water. Those two requirements point in opposite directions, which is why she left on 26 June 2017 and then waited, and finally slid under the bridge close to midnight with her hinged mast folded down and something under six feet of air between the top of it and the ironwork above. Every one of those numbers rests on somebody having measured the water accurately first, and the somebody was a fifteen-metre launch with eight people aboard.

She followed this with further survey work at Portsmouth Naval Base, scouring the approach channels and harbour entrance so the Navy could redraw its charts with confidence. As Lieutenant Commander Marc Taylor, one of her survey officers, put it at the time, the work would "allow us to produce new charts so we can be absolutely confident that the approach channels into the harbour are deep enough to allow her to come into port without any problems".

Years earlier, that same Portsmouth expertise had a rather more delicate application: before roughly £100 million and 3.5 million cubic metres of clay, sand and gravel were dredged out of the harbour approach to make room for the new carriers, HMS Gleaner was sent to survey the wreck site of the Mary Rose, Henry VIII's flagship, to make quite sure nothing of the Tudor wreck lay in the diggers' path. It is not every survey launch that gets to check on a 16th-century warship before clearing the way for a 21st-century one.

The scale of what she was clearing the way for is worth pausing on too. That dredge widened and deepened the approach channel, the harbour entrance and the turning area to take two ships drawing around ten metres apiece, in a harbour that had spent four hundred years accommodating nothing anywhere near that size. Somewhere in the middle of the works stood the Mary Rose site, a scheduled monument and a war grave, which had already given up the hull now in Portsmouth but was known to hold a great deal more. Getting a survey launch to prove the boundaries of it before the trailing suction hoppers arrived was not ceremonial. Her successor went back over the same ground for the same reason, as told in the article on HMS Magpie (H130).

It is a remarkably fitting piece of naval trivia that the Royal Navy's smallest ship played a direct hand in clearing the way for its largest.

Farewell to the Navy's Smallest Ship

HMS Gleaner attended Portsmouth Navy Days in 2010, one of the more public appearances in a career largely spent working quietly rather than showing off, and made her final entry into port at Plymouth on 31 January 2018, flying a 16-metre paying-off pennant streaming out far behind her modest 15-metre hull, before formally decommissioning that February after 35 years of continuous service. Able Seaman Bradley, her signaller for that last homecoming, said it was "fantastic to be part of such an important tradition" despite the wet weather, while Captain Gary Hesling, the Hydrographer of the Navy and a former commanding officer of Gleaner himself, was there on the jetty to meet the crew as they stepped ashore.

Her decommissioning ceremony took place at Devonport Naval Base on 19 February 2018, attended by several of her previous commanding officers and Commodore Rob Bellfield, Commander of the Devonport Flotilla, as guest of honour.

Her final commanding officer, Lieutenant Commander Will Alexander, remarked that he was 'very proud to be part of the final crew on one of the Royal Navy's longest serving vessels', a fair summary of a ship whose modest size never quite matched the length or usefulness of her service.

HMS Gleaner was replaced that summer by HMS Magpie, an 18-metre catamaran-hulled survey vessel with autonomous underwater vehicles at her disposal, technology that would have seemed like genuine science fiction to Gleaner's original 1983 crew. Will Alexander ended up bridging the two ships in person: having already served aboard Gleaner twice, he went on to become Magpie's first commanding officer too, making him the one man to have skippered both the Navy's outgoing smallest ship and the one that replaced her.

The pennant deserves a footnote of its own. A paying-off pennant is flown from the masthead when a ship leaves harbour for the last time, and the custom is traced to the nineteenth century, when the ship's cleaning rags were knotted end to end and hoisted to show that nobody would be needing them again. The length is variously reckoned as the length of the ship plus a foot for every year in commission, or a foot for every month; by either measure Gleaner was entitled to a good deal more than sixteen metres, and long pennants of that sort usually need balloons to hold them clear of the water. Hers streamed out behind her over a hull barely a metre shorter than the flag, which is either a very poor showing or the most concentrated paying-off pennant in the fleet, depending on how you look at it.

Legacy

HMS Gleaner's career is a reminder that naval history is not made only by battleships and carriers fighting dramatic actions; it is also made, patiently and repeatedly, by small survey vessels charting the water beneath everyone else's keel.

For 35 years, HMS Gleaner did exactly that, from the English Channel to the Rhine, closing her career by helping guide the Royal Navy's newest and largest ship safely to her new home.

The name has form as well, and the earlier holder of it did something rather startling. HMS Gleaner (J83) was a Halcyon-class launched in June 1937 and, like her namesake, completed as a survey ship, before the outbreak of war saw her converted to a minesweeper. In the small hours of 12 February 1940 she was on patrol off the Firth of Clyde when her hydrophones picked up a submarine. U-33 had been sent to lay mines in the Clyde approaches; Gleaner depth-charged her twice, brought her to the surface at about half past five in the morning, opened fire and turned to ram before the German crew began abandoning ship. Twenty-five men went down with her and seventeen were pulled out of the water.

What happened next was worth more than the U-boat. Three of U-33's crew had been detailed to throw the rotors from the ship's Enigma machine over the side before she was lost, and one of them, Obermaschinenmaat Friedrich Kumpf, did not. When the survivors were searched on the way into Greenock, three rotors came out of his trouser pockets: wheels VI, VII and VIII. The German navy used a larger set of wheels than the army or the air force, and the wiring of two of those three was unknown to Bletchley Park. They went south, and they mattered. A minesweeper that had been built as a survey ship, doing an ordinary night patrol off Arran, handed the codebreakers a piece of the naval Enigma problem they had no other way of getting. It is a decent thing for a name to have on its record, and a reminder that the quiet ships are not always the ones with nothing to show for themselves.