Blue Tint Curve

有誰知道Blue Tint Curve的意思?
謝謝!

Blue tint in water areas

A blue tint is shown in water areas on many charts to accentuate shoals and other areas considered dangerous for navigation when using that particular chart.

Since the danger curve varies with the intended purpose of a chart a careful inspection should be made to determine the contour depth of the blue tint areas.


http://www.nauticalcharts.noaa.gov/ns ... s/cp4/CP4-40ed-Ch01_4.pdf

有看沒有懂....有沒有高手可以指點一下

會不會是指需要特別注意的淺水區域？
請先進協助確認～

『A blue tint (Blue Tint No. 1) is shown on the
chart to emphasize shallow water areas considered
dangerous to navigation.』==>碩大指的淺水區 The depth contour selected as the boundary for the tinted area is not
a constant for all charts, but rather determined by
the chart scale, prevailing depths available, and
the draft of the vessels expected to navigate within
the charted area. The limit value for the tint for
any chart can be determined by noting the soundings
on either side of the tinted area.

另外亦可標示水深少於20公尺之礙航物..『A blue tint is
used within a danger curve to mark depths of 66 feet or 11 fathoms or less.』例如礙航沉船, symbol為十字架周圍用點圈起來,內用blut tint 強調。

Reference: NOAA Chart User's Manul

也請先進指教

我不是高手、前輩或先進，不過趁路過幫個小忙而已。
blue tint是藍色調，curve是曲線，舉世海圖皆以藍色調代表淺水水域，blue　tint　curve的意思因此是藍色調曲線，亦即把淺水水域圍起來的等深線（depth contour）。
A blue tint is shown in water areas on many charts to accentuate shoals and other areas considered dangerous for navigation when using that particular chart.　許多海圖係根據特定用途以藍色調強調水域內的淺水水域及其它被視為對航行構成危險的水域。
Since the danger curve varies with the intended purpose of a chart a careful inspection should be made to determine the contour depth of the blue tint areas.　危險線（danger curve，亦即把淺水或其它危險物圍起來的曲線）係隨海圖的既定用途而定，使用海圖時應先仔細檢查圖上的藍色調水域，再決定採用其中哪條等深線。

Thanks for bigfoot and the others above, I am now totally understanding.