Navigation in Coral Region

 

    Corals are living organisms which they grow live and die. Corals required sunlight, clear water, warm water temperature, clean water and salty water for survive. Since corals need sunlight to exist they grow commonly in shallow water. The depth of sea in coral regions gradually decrease with the growth of corals. It can be determined as 0.3 meter per year. Corals grow in areas where water flows. Corals grow windward side of the islands other than leeward sides of the islands. As a result windward channels can be blocked by the coral debris and by the inward growth of the corals. The leeward channels are usually clear because due to the ebb debris deposits in deep water outside the reef.

    Soundings may give little warning of proximity of reef and also the echo sounder trace may be very weak due to the steepness of the gradient. Take into account the survey date. If it is an old survey, proceed with caution. A common feature of coral regions is lack of fixing marks and navigating with the help of eyesight, there for

• Place lookouts aloft and forecastle.

• Coral can best be seen from masthead.

• Above 20⁰ elevations for the sun is best.

    Sun should be behind the observer and sun should be unobscured by cloud. A sea slightly ruffled by the wind makes for better visibility.  Glassy calm sea makes it difficult to distinguish the color differences between shallow and deep water.  When Polaroid spectacles are worn, these allow differences in color of water to stand out more clearly.

    In good weather corals can be seen with a height of about 10 – 20 meters. Coral patches with depths less than 6 – 8 meters should be visible at about half a mile.  Windward or exposed side of coral reefs are more uniform than leeward side. Windward side may have water breaking over it thus more easily seen. Leeward side frequently have detached coral heads which may not be seen. “Pass on the weather side” because edges and off lying pinnacles will be shown by breaking water.