New Soundings

New Zealand Listener, Volume 29, Issue 734, 7 August 1953, Page 6

New Soundings

listens for the answer, is the chief character in a new NZBS feature, An Ear to the Ocean, which will have its first broadcast this week. The ship, which has been around the New Zealand coast for several years, is "a curious sort of vessel, a man-o’-war that carries no guns, a frigate whose: key officers and’men are as much at home with pen and ink and a calculating machine as they are with tides and winds." This is the survey ship Lachlan, a Royal Australian Navy frigate on loan to the Royal New Zealand Navy, and now engaged in sounding the waters around the New Zealand coast. A few months ago Trevor Williams, of NZBS Head Office Talks Section, and himself a former naval officer, went to sea for four or five days in Lachlan. With a portable tape-recorder slung over his shoulder-the first time one of these had been used by the NZBS-he talked to some of the people engaged in the survey, from the Commanding Officer, Commander C. C, Lowry, R.N., down. Linked with some interesting sound effects and Mr. Williams’s commentary, these interviews add up \ to the feature that listeners are now to hear. SHIP that ticks, that "shouts" at the sea-bed and ~ Since An Ear to the Ocean was recorded, Lachlan has paid a short visit to Fiji, and spent a month off the Samoan coast----where, by the way, she sailed in 340 fathoms of water over a "reef" that mariners have been avoiding for years. The frigate had not been long back at Wellington when The Listener went aboard to ask some questions. In the after deckhouse, where most of the paper work is done, it found Commander Lowry, a tall, pleasant, bearded man, who next Boxing Day will complete 20 years in survey work. We discovered that he is used to explaining his job to outsiders. Not only has he had the NZBS and the National Film Unit aboard recently-he was also technical adviser for a documentary film, Charting the Seas, made soon after the war by the Central Office of Information and the British Council

and available in 12 languages. Though Commander Lowry has been with Lachlan for only a little over a year, the ship, as most people will know, has been on the New Zealand coast. since 1949. In that time she has finished her work in an area from Foveaux Strait to a little north of Dunedin, and +: from Banks Peninsula up through Cook Strait almost to Wanganui, and to Honeycomb Rock on the east coast of the North Island. She has also completed new charts and plans. of Wellington, Lyttelton, Port Chalmers and Bluff Harbours, as well as such other inlets as Aka-

roa, Porirua, Paterson Inlet and Port Underwood. Though publication of new charts by the Hydrographic Office naturally lags a little behind the completion of survey work, three new coastal charts and six harbour charts and plans have already been published and two coastal charts and one harbour chart will be published soon. "The two big launches which do the harbour survey work should finish Gisborne harbour by the end of October," Commander . Lowry said. "When the weather improves we will complete our soundings between Honeycomb Rock and Castle Point-there’s about another two months’ work there-and _- the charts for this area and for Gisborne should be published next year, By that time we’ll be working further north up the east coast. Our next harbour survey , will probably be at Napier." The work of the survey depends very much on the weather. We had heard it said that it would take something like another 30 years to complete the resurveying of the New Zealand coast and harbours, — but Commander Lowry wouldn’t commit himself on that one. All he would say, with what we gathered was a certain amount of wilful exaggeration, was that if the weather was no better than it had been this year the job would take "hundreds of years." Rain and mist -lack of visibility for taking "fixes" on points ashore-rather than wind is the main obstacle, thoug’ high winds also add to the ship’s difticulties. Very good weather is needed if the ship’s two small motor-boats are to do the inshore soundings. Generaily speaking, Lachlan doesn’t go closer than a mile and a half from the shore, though it can get as close as half a mile if the bottom is known to be flat’ and sandy. In the last section of the survey completed, between Cape Palliser and Honeycomb Rock, the motor-boats were able to work on five days in about two months-which, from what he had learned of the New Zealand weather in the past year, Commander Lowry thought was "pretty good." Roughiv two-thirds of the inshore soundings have been taken for the chart of this area. While The Listener was examining the sheet of pale blue tracing paper which showed the gap in these inshore soundings, Commander Lowry was ex‘plaining the difference between this sheet, which is called a "collector," "plotting sheets," on which all impor:ant points are marked, "fair tracings" (continued on page 7)

(continued from page 6) , and the final "fair chart." We noticed that the existing Admiralty chart for. the Cape Palliser-Honeycomb Rock area showed very few soundings. Commander Lowry said that there were actually only about 25. marked on this chart compared with 10,000 to 12,000 on the collector from ‘which the new fair chart | would be prepared. However, it was the number of lines of soundings rather | than the. actual number of soundings which indicated the amount of work. done by the survey ship, and the fair chart in this case would show only from | one-twentieth to one-twenty-fifth of the number of soundings recorded on the collector. It wasn’t necessary, for example, to show so many soundings in deep sea as around a reef. Commander Lowry had been drawing his examples from the area north and | south of Honeycomb Rock in which Lachlan has worked in recent, months, | and this was specially interesting to us since An Ear to the Ocean was recorded while the vessel was sounding between Honeycomb Rock and Castle Point. | When we asked him about data on ex- |} isting charts which had been proved or Uisproved by Lachlan’s survey, he took us once again to the Honeycomb Rock | area where the 50-fathom line is shown about seven miles off the coast. "In reality,’ he said, "it’s nearer three miles. In other words, a master getting 50 fathoms off Honeycomb Rock would | think he was seven miles out to Sea | when in fact he was almost on top of Rangatira Rock. This could, of course, | be very dangerous to navigation, and > we weren't very happy when we were | -in this area. On the other hand, we) found not far away a depth of 75, fathoms where 11 fathoms had been ze- | ported, and 180 where the old chart | showed 39."

The coastline here had been badly charted and was a bad one to "fix" on, said Commander Lowry, and this might be the cause of the errors on the existing charts. In fact, the coastline »n New Zealand charts generally was bad because of the poor information originally given to the Admiralty,-and to help mariners the present survey was taking photographs of the coastline wherever possible. Commander Lowry said that in spite of such discoveries as the dangerous state of the chart off Honeycomb Rock. the Lachlan survey had found that it was disproving rather than proving the existence of dangers marked on existing charts. Some of the shoals reported in the past might be due to. the careless use of the echo-sounder-because it was quite possible, if you weren’t watching what you were doing, to get a reading of, say, 20 fathoms when the depth was really 620 fathoms. Other errors might be caused by a false bottom-a shoal of fish or even sediment in the water. (Modern British trawlers wouldn’t go to sea without an echo-sounfer, Commander Lowry said, and they were. even able to differentiate between shoals of different types of fish.) During the war when he spent six years in Australian and New Zealand waters, Commander Lowry surveyed Sydney Harbour to see whether it was safe for the Queen Mary to enter, and among the false bottoms which troubled him was a piece of wire and chalk particles from a block cf chalk which had evidently dropped from a barge. "When a rock or a shoal is reported on an important shipping route we try to get there as quickly as possible, but it would make things easier for us if mariners would take a lead-line sound-

ing when they get a doubtful reading on the echo-sounder,’"’ Commander Lowry said. "Quite recently two shoals, ‘three or four miles apart and 10 and 12 fathoms down, were reported off Great Barrier Island, We got 100 fathoms over them. We were able to.disprove the -existence of a rock near French Pass, though we found another right in the middle of the Pass. Another discovery was a smallish pinnacle, which was a danger to overseas shipping, in Gisborne arbour,’ Commander Lowry added, in reply to a query, that false echoes didn’t give much trouble to the experienced surveyor, "We've been at this job.a long time and we understand a lot about echoes," he said. "But if we do have any qualms we go back over the spot again." Just what happens in the day-to-day work of Lachlan’ while she is doing her job at sea listeners will hear when An Ear to the Ocean is broadcast for the first time at 3.30 p.m. this Sunday (August 9) from 2YA. Among the voices they will hear are those. of Commander Lowry, Senior Commissioned Mechanician Mitchell (engineer officer on Lachlan), and Martin Skerman, an officer of the Department of Scientific and Industrial Research, who is on Lachlan ito gather samples of ocean life. They wiil also hear the echo sounder at work; officers taking a fix, an impression of the work going on in the after deckhouse, and a description from Trevor Williams of many other details of the work of the survey ship as only a man on board could see it. An Ear to the Ocean will be heard also from 1YA at 2.0 p.m. on Sunday, August 23, and later from. other YA and YZ stations, Pe ot Oe PR see Bat eae?