DC Sailing Community Seychelles 2021 Flotilla Pilot Notes Adapted from: Admiralty Sailing Directions, South Indian Ocean Pilot, NP39 16th Edition 2020 UK Hydrographic Office Protected by Crown Copyright 2020. DC Sailing Community use only. Not for resale. 1 Observations of the Southern Indian Ocean Piracy and Armed Robbery General information The British Maritime and Coastguard Agency has brought to the attention of shipowners, masters and crews, the risk of acts of piracy on the high seas or armed robbery against ships at anchor, off ports or when underway through the territorial waters of certain coastal states. The UKMTO (United Kingdom Maritime Trade Operations) has established a designated Voluntary Reporting Area (VRA) covering all the waters of Red Sea, Gulf of Oman, Arabian Sea and Indian Ocean S of Suez and Straits of Hormuz to 10°S and 78°E. The High Risk Area (HRA) is an area within the UKMTO VRA where it is considered there is a higher risk of piracy and within which self-protective measures are most likely to be required. The high risk area is bounded by: ● Parallel 15°N in the Red Sea. ● The territorial waters off the coast of E Africa at latitude 05°S. Then to positions: ○ 10°00.OON 60°00.00E. ○ 00°00.OON 55°00.00E. ○ 14°00.OON 60°00.00E. ● Then a bearing 310° to the territorial waters of the Arabian Peninsula. Note that our sailing grounds within the Inner Seychelles Island Group do not fall within the above boundary coordinates and are not considered at risk from piracy. Recommended practices Recommended practices, including anti-attack plans, reporting, use of AIS, radio procedures and responses are outlined on chart Q6099 and The Mariner's Handbook. A list of anti-piracy contacts is published in ADMIRALTY List of Radio Signals Volume 1(2). Additional guidance can be found in Best Management Practices for Protection against Somalia Based Piracy, available from the Maritime Security Centre (Horn of Africa) website (www.mschoa.org). Details of the current prevalence of reported piracy and armed robbery for all regions may be found on the website (www.icc-ccs.org) of the International Chamber of Commerce Commercial Crime Services. Reporting Piracy warnings are received and issued by the Piracy Reporting Centre at Kuala Lumpur for the area covered by this volume. Details of the current reported piracy and armed robbery for all 2 regions may be found on the International Chamber of Commerce Crime Services website www.icc-ccs.org. IMB Piracy Reporting Centre Tel: +60 3 2078 5763 / +60 3 2031 0014 E-mail: [email protected] / [email protected] Buoyage System The IALA buoyage system Region A (red to port) is generally in use in the waters covered by this volume. Distress and Rescue For general information concerning distress and safety, including helicopter assistance, see ADMIRALTY List of Radio Signals Volume 5 and The Mariner's Handbook. Throughout the waters covered in this volume, the principal means of searching for and assisting persons in distress is through GMDSS. The basic concept of GMDSS is that SAR organisations ashore, as well as shipping in the immediate vicinity, will be rapidly alerted to a distress incident so that they can assist in a co-ordinated SAR operation. Within the regions covered, there are National SAR Agencies, and MRCCs or RCCs. Within the area of this volume, there are STARS for Australia, India, Madagascar, Maldives, Mauritius, La Réunion (France), Seychelles and South Africa, and small parts of the SRRS of Mozambique and Tanzania. For full details including diagrams, and a list of DSC stations, see ADMIRALTY List of Radio Signals Volume 5. Automated Mutual-assistance Vessel Rescue System AMVER provides world-wide cover, giving important aid to the development and co-ordination of SAR efforts in many offshore areas of the world. It is operated by the United States Coast Guard, and merchant vessels of all nations making offshore voyages are encouraged to send movement reports and periodic position reports to the US Coastguard. 3 Sea Level and Tides Tides In that part of the Indian Ocean covered by this volume, the tide is generally of a regular semi-diurnal nature; this is especially the case at Comores, the W coast of Madagascar, Chagos Archipelago and ile Saint-Paul. In Seychelles Group and at La Réunion and Mauritius, there is some diurnal inequality of heights of the two HWs. The largest tides occur on the W coast of Madagascar between Toliara and Nosy Be; at Mahajanga, the mean spring range is 3.8m. There is little rise and fall on the E coast of the island; at Taolanaro, tidal movements are difficult to observe. At La Réunion, the mean range is only about 0.3m. 4 5 Sea conditions In the SE trade wind belt, moderate seas are usual in all seasons, with waves 1 to 2m high. Occasionally, when the wind freshens, especially from June to September, seas can become rough, but waves rarely exceed 3 to 4m. Calm seas are unusual except in sheltered areas. Further S in the subtropical high pressure belt, slight or calm seas are common during the lengthy spells of light variable winds; however, troughs of low pressure and associated fresh winds bring interludes of moderate to rough conditions. Swell conditions Apart from tropical storms and cyclones, the principal generators of swell are the SE trade winds, the generally W winds of the Roaring Forties and, to a lesser degree in equatorial waters, the NE monsoon of the N hemisphere and its extension into the S hemisphere, the NW monsoon. Although swell waves and sea waves generated locally are usually present simultaneously, swells are generally much longer in length and period. Swell can cause uncomfortable conditions in an otherwise calm and smooth sea. From the equator to 20° to 25°S, swell is predominantly ESE throughout the year, generated by the SE trade winds. Wave height averages 1 to 2m but can reach 3 to 4m. Heights tend to be lowest farther N; swells are highest in winter, and lowest in summer. The NE monsoon of the N hemisphere raises moderate swells which reach equatorial regions during the S hemisphere summer (December to March). The NW monsoon which blows S of the equator during the same season raises low, occasionally moderate, NW swells as far S as 10° to 15°S. Associated N to NE swells affect the N part of Mozambique Channel. 6 7 Tropical disturbances Mountainous and confused seas are raised by the violent winds associated with tropical storms. Near the centre of a storm, groups of large waves moving in different directions have very irregular wave heights and can occasionally combine to produce an exceptionally high wave in excess of 30m. Swell travels radially outwards from the storm circulation, with the highest swells moving ahead of the storm roughly in the same direction as the storm track. This swell may be an early indication of an approaching or distant storm and also give some indication of the approximate bearing of the storm centre. When a storm approaches land, abnormally high tides may be caused; with the addition of heavy swells, and later very high seas, severe flooding can occur in low-lying areas. Occasionally, an exceptionally high wave or wall of water may race in from the sea with catastrophic consequences. Sea Surface Temperature Diagrams 1.104.1 to 1.104.4 show the mean monthly sea surface temperature distribution for February, May, August and November. The distribution pattern changes little through the year and, in equatorial waters, sea surface temperature varies only 1° to 2°C seasonally. To S of about 20°S, sea temperature falls fairly steadily from February to August by about 4° to 5°C. Thereafter, values increase again fairly steadily, towards the February maximum. Near the equator, sea temperature is usually within 1° to 2°C of the monthly mean value. Further S, variability increases and, in the S of the region, deviations from the mean of 3° to 4°C have been noted. 8 Climate and Weather Routine weather reports and forecasts for the area covered in this volume are broadcast regularly, in different languages, from shore stations. Gale and storm warnings are also transmitted as necessary. 9 Variation in general conditions of climate and weather with latitude is a marked feature of the extensive region covered by this book. In summer, from December to March, the N part of the region, as far as about 15°S at its greatest extent, is affected by hot and humid conditions associated with the Inter Tropical Convergence Zone (ITCZ) and the NW monsoon which move seasonally. To S of the ITCZ, the SE trade winds blow throughout the year in an extensive belt, the width of which varies with movement of the ITCZ. Conditions in this belt are generally warm and pleasant with well-broken cloud and sunshine predominating, but scattered showers may occur, especially in the N. The wind brings rain to the windward sides of the larger mountainous islands; by contrast, leeward coasts and slopes enjoy clearer skies, fine weather and higher temperatures. To S of the SE trade wind belt, the region is dominated by a sub-tropical high pressure belt in which weather conditions are generally good. In the S part of the region, S of the subtropical high pressure belt, there is a zone of strong W winds, cloud and rain. Visibility is generally good throughout the region, although it can deteriorate rapidly in heavy rain when visibility may fall below fog limits. Fog itself is rare at sea.