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Beginner Chart Reading Question

Folks,

I have a basic question regarding depths on paper charts.

My maptech paper charts sound in meters. However, on some readings there is a small number down and to the right of the the sounding.

I have no idea what that number is... I have searched chart 1 for that information but I cannot find a clear reference to it. The numbers will vary greatly even if the depth remains the same between two points.

I was suspecting that they were alternative soundings but I want to make sure. So - what are they?

- z
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post #2 of 9 Old 03-24-2011
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Quote:
Originally Posted by zboss View Post
Folks,

I have a basic question regarding depths on paper charts.

My maptech paper charts sound in meters. However, on some readings there is a small number down and to the right of the the sounding.

I have no idea what that number is... I have searched chart 1 for that information but I cannot find a clear reference to it. The numbers will vary greatly even if the depth remains the same between two points.

I was suspecting that they were alternative soundings but I want to make sure. So - what are they?

- z
That would be 10ths of a meter.

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That would be 10ths of a meter.
OK! so... 15 with a little 2 next to it means 15.2 meters/49.8 feet.

Thanks.
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post #4 of 9 Old 03-24-2011
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This is something to be REAL careful with when you switch charts and pilots.

Some give the depth in metres some in fathoms with the small numbers being feet and some in feet.

Something I triple check always.
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An easy check: if the small number is larger than 5, it is probably metric.

Always read the title block of a chart. It has essential information.

Even though Canadian charts are usually metric, we still have some that are in fathoms and feet.

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They are making charts with the metric system in the US now? Drat! Anyone know how many meters in a fathom ?

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Quote:
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They are making charts with the metric system in the US now? Drat! Anyone know how many meters in a fathom ?
2 meter = 1 fathom approximately

or more precisely 1 fathom = 1.8288 meters

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Quote:
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They are making charts with the metric system in the US now? Drat! Anyone know how many meters in a fathom ?
If you use digital charts you set the unit of measure on the chart plotter (I can on my Furuno at least
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Quote:
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If you use digital charts you set the unit of measure on the chart plotter (I can on my Furuno at least
The OP is using paper charts. The depth can be set on vector charts, but not on raster charts. Some of my Canadian rasters are in fathoms and feet, but the vast majority are metric.

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