Hid­den depths

Yachting Monthly - - LETTERS -

I read with in­ter­est Craig Hardy’s ar­ti­cle ‘Keep­ing a look­out us­ing elec­tronic nav­i­ga­tion aids’ [YM, June 2018] on what I term ‘elec­tron­i­cally as­sisted ground­ings’. Nowhere in the ar­ti­cle does he ques­tion if the lat­i­tude and lon­gi­tude for the reef or other atolls on the plot­ter are ac­tu­ally cor­rect. I refuse to be­lieve that ev­ery re­mote reef, is­land or atoll in the world has been re­cently sur­veyed. I re­mem­ber, al­beit 20 years ago, go­ing into Lau­toka in Fiji; the chan­nel was two miles to the west of the elec­tronic po­si­tion. The chart was show­ing cor­rect depths and po­si­tions rel­a­tive to the land but in­cor­rect as to GPS. One of the crew told me that we had two miles to run to the buoyed chan­nel to Lau­toka. I pointed out that we were one mile from the chan­nel and that if we went two miles, we would be half­way up the run­way at Nadi air­port. He could not un­der­stand why this was the case. I pointed out that Cap­tain Dampier (English ex­plorer and nav­i­ga­tor) or who­ever’s chronome­ter was two sec­onds out when the area was orig­i­nally sur­veyed, so the chart was out by two miles.

Nearly 50 years ago, when I was study­ing for my Mas­ter’s cer­tifi­cate, we were told firstly to al­ways en­sure that an alert vis­ual watch was main­tained and se­condly, never as­sume that any one po­si­tion placed on a chart is cor­rect un­til it had been ver­i­fied by a sec­ond. That is why three sights were al­ways taken and then again checked by another of­fi­cer. Nowa­days, I ob­vi­ously use plot­ting pro­grammes on my yacht but I still try and use the Mk I eye­ball when­ever pos­si­ble. David Buck­pitt

David warns that lat­i­tude and lon­gi­tude on charts for re­mote ar­eas like Fiji are not aways cor­rect

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