The Ruia and Lingga Islands, Northern Indonesia.

Cruised using the “Gateway Scheme C.A.I.T”, and “Green Book”.

We have just returned from a short cruise around these islands (Saturday 26 June 2010). The following observations and notes may be of interest.

Navigation

We used British Admiralty Charts “3949”, Selat Riau, and “1789”, Pulau – Pulau Lingga. The former is reasonably modern, the surveys were carried out between 1951 and 1976. The latter is a bit long in the tooth as the survey was carried out between 1896 and 1901. Later information has been added to both charts. Neither is to WGS84 datum, and large positional corrections are required for both. We found inaccuracies of up to 0.6 nm on chart 1789. Both were obtained from the Admiralty Chart Agent in Singapore, off the shelf, both being corrected before sale.

We also use electronic cartography (Navionics, on a Raymarine display). We found that this was as good as, if not better than, the paper charts.

The depths charted on both systems are wildly inaccurate, due to insufficient soundings. Much less water being apparent numerous times, with appreciable, uncharted, obstructions nearly everywhere. There were also large areas of much deeper water. We use a Raymarine DSM 300 sonar as well as the more orthodox depth display. The DSM is far more sensitive to depth changes and the nature of the sea bed can be ascertained as well. The uncharted obstructions show up far more clearly and more quickly, and can be readily plotted, thus correcting the charts. Whatever depth display you use, expect it to jump up and down a lot!

Indonesian Charts are supposed to be available, we tried to obtain some from a large, local, book shop, only to be told that they have to be ordered from Jakarta. Quoted delivery times were, shall I say, dubious.

Weather

We cruised in June 2010, the weather should have been light breezes from the SE – SW, as the season was changing from the NE monsoon to the transition period before the SW monsoon sets. The sea state should have been slight, except on eastern coasts, where moderate swell could be sometimes expected. We experienced an NW force 7 and an SE force 8! We had 2-metre swell on several occasions. Squalls, thunderstorms, torrential rain, and even an embryonic water spout were also experienced.

Weather forecasts were picked up each day from the Navtex station in Singapore. It never varied, always being SE – SW, 5 – 10 knots, sea state slight!

The Pilot Books for the area seem to be written for the NE Monsoon period, as the recommended anchorages therein offer protection from this quadrant. However, there are numerous anchorages to be found with adequate shelter from the South.

Tides

The area is tidal, with reported tide streams of up to 3 knots (we saw one of 4 knots). The flows are tortuous around the islands but generally set West & South for the flood, East and North for the ebb. The strong streams scour the sand and mud from many of the channels and areas around islands. Anchoring can be a bit hit and miss if you miss a sandy / muddy area. We found that deeper water ( 10 – 15 metres) had a better holding, but we still needed to lay more than 65 metres of chain out due to the currents. Tide tables are said to be available, but we never found any. Tides are diurnal in the North, a single tide predominating in the South.

Navigation Warnings

The Indonesians were very friendly, we never actually visited any villages, but the passing traffic always smiled and waved.

They use two major fishing methods, other than fishing boats. The construction of fish traps, up to 100 metres long, composed of thin wooden stakes and withies, to herd fish into an enclosure close to the shore, and fishing platforms, which are large structures, made of tree trunks, usually situated in 5 – 10 metres of water. These platforms operate at night, attracting fish under their large gas lights. The area under the lights is fitted with a net, which is pulled up, trapping the fish. In both cases abandoned, redundant and damaged versions litter the coasts and shallows. It pays to be cautious when navigating in the areas where they are situated. The nets set by fishing boats have plastic water bottles as marker floats, a sharp lookout is necessary!

The local fishermen mark reef edges with stakes, this was very useful to us, as it gave an idea of the extent of the fringing reef, when anchoring.

The islands are rich in iron ore deposits, and numerous barges and lighters were encountered. They were supplying the ore to large bulk carriers anchored in the deeper channels. These bulk carriers could be up to 900 feet long! The tugs pulling the barges showed the correct signals, but the barges were unlit.

The area is well provided with fast (20 – 25 knots) ferry boats, which travel from island to island, and to Singapore. They seem well maintained and are piloted by courteous captains. They are also well lit at night and usually carry an AIS transponder.

We had one occasion to sail at night. It was not a pleasant experience, and we would not recommend it. The navigational aids were usually missing, or if they were on station, they were unlit, or the light characteristic was incorrect. The fishing platforms, mentioned above, showed up well on radar, at 1 – 2 nm range.

Conclusion

We saw no other private yachts or cruising folk the whole time we were in the region.

We crossed the equator while cruising the Lingga Islands, which was the main purpose of our cruise, and experienced the best weather in that area. The uninhabited, typical tropical islands, with white sand and palm trees, were beautiful and made the trip worthwhile.

Jerry & Caz

SY Mandarina