tidal streams

Question 1

what is a tidal stream

Answer 1

a flow or current of water caused by the tide

Question 2

why does a skipper need the tidal stream to work out an estimated position

Answer 2

the current carries the boat with it, causing it to move difrently than on a flat body of water so it needs to be accounted for

Question 3

what 3 things impact the strenght and direction of a tidal stream

Answer 3

the location of the vessel, Weather the tide is neaps, springs or midrange, and the time relitive to high water at the refrence port

Question 4

Why do you not want to sail against the tidal stream

Answer 4

it will subtract from your speed, causing the voyage to take longer

Question 5

Why do youw ant to sail with the tidal stream

Answer 5

it adds tot he vessesl speed, causing the boat to move faster

Question 6

What is the COG

Answer 6

Cource over ground

Question 7

if a vessel is sailing at 4 knots, and the tide is flowing with the vessel at 4 knots, what is the Sog

Answer 7

8 knots

Question 8

if a vessel is sailing at 4 knots and the tide is flowing against the vessel at 4 knots, what is the sog

Answer 8

0 knots

Question 9

if the Sog is 0, will the log read 0 if sailing into an aposing current

Answer 9

no, as it mesures the speed through the water

Question 10

What is a tidal diamond

Answer 10

a mark on a chart that links with a table on the chart to give tidal stream information

Question 11

When using a tidal stream table, where is the refrence port listed

Answer 11

at the top of the table

Question 12

Which timeframe does each entry on the tidal stream table refrer to

Answer 12

half an hour either side of the time relitive to high water

Question 13

what 3 bits of information are listed in the tidal stream table for a given time and location

Answer 13

the tidal set (bearing) and two tidal drift mesurments, one for spring tides which is first and one for neap tides which is second

Question 14

how do you know if it is a neap or spring tide when using the tidal stream table

Answer 14

Using the tide table for the reference port, work out the range for the tide, and compare it to the tidal neaps and spring ranges located on the tidal curves to see which it is closer to

Question 15

what is a tidal laddar

Answer 15

a way of writing out times to work out which highwater hour to use for a given period at sea

Question 16

What are the steps for constructing a tidal lader

Answer 16

work out the closest time of high water to when you are sailing. Convert to BST if nessacary. Then work out half an hour backwards and forwards from the high tide, this is the first time range. Then subtract an hour from this to get hw -1 hour, and repeat to get hw -2 through 6, then add 1 hour to get hw+1 and repeat to get hw +2 through 6, then take the time period which suits the time being sailed

Question 17

What is a tidal stream atlas

Answer 17

its a chart of the area sailed with lines added on representing tidal streams

Question 18

why should an atlas be used instead of an atlas

Answer 18

there are many more measurements, leading to a more accurate plan to be made

Question 19

when a tidal stream is written as 02.12 what is the neap and spring tidal drift

Answer 19

neaps = 0.2 knots
springs = 1.2 knots

Question 20

if an arrow on a tidal stream atlas is curved, how do you get the tidal set

Answer 20

take it from the tif of the arrow to the base of the arrow to get the average of the angle