Master Yachts | Tides

Question 1

What is ‘CD’?

Answer 1

• Chart Datum
• Normally the lowest you would expect the tide to fall at any given location.

Question 2

What is ‘HAT’ and where is it measured from?

Answer 2

• Highest Astronomical Tide
• Measured from CD

Question 3

Define ‘Drying Heights’.

Answer 3

Measured above Chart Datum.

Question 4

Define ‘Height of Bridge’.

Answer 4

Measured from Highest Astronomical Tide (HAT) or Mean High Water Springs (MHWS)

Question 5

Define ‘HoT’

Answer 5

• Height of Tide
• Measured from CD

Question 6

Where would the height of a lighthouse be measured from?

Answer 6

From Mean High Water Springs (MHWS)

Question 7

What effect does the sun have on tides in comparison to the moon?

Answer 7

The sun has half that of the moon.

Question 8

What is one method for interpolation for times and heights of tides?

Answer 8

Sharks tooth method - the drawing of a horizontal V, the bottom line divided hours or metres, whichever is appropriate.

Question 9

What form template is found in the Admiralty Tide Tables for tidal predictions?

Answer 9

The Tide Prediction Table.

Question 10

What is the ‘percentage spring’ calculation?

Answer 10

• Used to interpolate when the range is between the Mean Spring and Neap ranges.

daily range - neap range / spring range - neap range
X 100
= % springs