Into The Depths Of Our Waters With MPA Hydrographers

Every day, hydrographers from the Maritime and Port Authority of Singapore go out to sea to survey and map the seabed of our surrounding waters.

MPA officers Wong Tuck Meng (right) and Choo Jun Gang (left) on the Lita Investigator vessel, used for hydrographic surveys. The boat has state-of-the-art survey equipment: three GPS antennae, a motion sensor that compensates for vessel movements in the water, and a Multi-beam Sonar Survey system that allows the seafloor to be visualised in 3-D and with high accuracy.

It is 9am, and we are setting off from Shell Jetty, a quiet private pier off Pasir Panjang Drive.

Mr Wong Tuck Meng, a hydrographer at the Maritime and Port Authority of Singapore (MPA), dons a pair of wraparound sunglasses. He strides across a docked boat and onto the Lita Investigator, a vessel equipped for hydrographic surveys.

To keep ships safe in Singapore’s waters, MPA hydrographers use precise technology to collect data of sea depths and the shape of the seabed. This data is processed and passed on to MPA cartographers, who further refine and chart the information on marine navigational maps.

A sound velocity probe (bottom picture) measures the speed of sound to determine water depth. It also calculates water density, salt levels and temperature, which can all affect the speed of sound in water. In the top picture, it is lowered into the water to take measurements. Mr Wong rinses the probe afterwards to prevent dried salt from damaging it.

Today’s mission is a “post-deployment survey” on the Banyan beacon, a navigational mark 1.4km southeast of Jurong Island. It was reinstalled two days ago, after a passing vessel had knocked into it.

It used to take five men, collecting data by hand, nearly three days to do the same work that a “one-man show” can now do in half a day.

“We want to check that nothing has been dropped on the seabed or left behind,” says Mr Wong, “and that the actual depth is not shallower than [reported]. If the map says [the depth is] 10 metres, it cannot be 9.9 metres.”

Inside, the Investigator looks like a mini office, with a “corner” table topped by monitor screens, and a small pantry to the left.

First up: a “range check” to verify that the GPS points in the system are accurate. As the Investigatornears a spot off PSA’s wharf, Mr Wong calls out commands in Malay to the boat captains – “kanan lagi” (further right), and “OK boss, sini, masuk” (here, proceed). His voice carries easily above the rumble of the engines.

Mr Wong chats in Malay with boat captain Mr Rahman, while pointing out where to go on the way to the Banyan beacon.

Hydrographic surveying is a job Mr Wong, 57, fell into “by chance”, he says. But it is clear that he takes pride in his work. He marvels at the latest technology for hydrography. In his 34 years on the job, Mr Wong has seen huge changes: it used to take five men, collecting data by hand, nearly three days to do the same work that a “one-man show” can now do in half a day.

Mr Wong has taken on more of a mentor’s role now, going out to sea every two or three months. Joining him today is 26-year-old Assistant Hydrographer Choo Jun Gang. Mr Wong shows him interesting points, such as the shallower parts of the seabed, as data streams across two monitor screens set up in the boat.

Left: Co-captain Mr Mazlan helps to activate the echo-locator on the port, or left side, of the boat. The echo-locator uses sonar and reflected sound waves to generate data about the seabed.

Right: Back at the MPA headquarters at Tanjong Pagar, Mr Wong has lunch from 1pm to 2pm. He prefers to take away his food and have the hour to himself in his cubicle, reading the newspapers at the same time, Mr Choo tells Challenge.

Top: After lunch, Mr Wong cleans up survey data from previous days, removing outlying points. He cannot work on today’s data yet as he has to wait for the tidal information from other surveyors still out at sea.

Bottom: These are scans of World War II shipwrecks discovered in 2012, in Singapore waters.

The MPA also ensures that seabeds are not too cluttered with objects left behind. “Ships that drop their anchors can get the chains stuck in the rubbish. Not being able to lift the anchor, the ships just cut it off , creating more rubbish,” says Mr Wong, Principal Technical Executive. The MPA will arrange for such debris to be removed if necessary.

In their surveys, MPA hydrographers have found wrecks of abandoned vessels. Dolphins are also a common sight in local waters. Mr Wong thinks he even saw a whale once, while in more open waters. “I saw something come up, a sprout of water, and something go down again,” he says, grinning. “But no one believed me.”