The range of the tide and the time of high water and low water is not the same each day. These are driven by the relative position of the moon (and to a lesser extent the sun). Fir example, here in Penzance tide time move forward by around an hour each day. When high water is around 06:00 and 18:00 (we have two high waters a day) we have spring tides and when high water is around 00:00 and 12:00 we have neap tides. Spring tide having a larger range than neap. The secondary port adjustment is different (generally greater) for spring tides compared to neaps. We can therefore calculate the size of the adjustment based on the time of high water.
@@pzsc thank you. I thought it was unusal to make an ajustment for time of high tide. But its just an ajustment for spring or neap nothing unusual there. I was starting to think it was to do with the position of the sun.
OMG... those triangles are kind of kinder garden level. Here is the adult method: Calculating time difference for HW 0854 1. Difference between 0000 and 0600 = 360 min. 2. Difference between -18 and -40 = -22 min 3. Difference between 0600 and 0854 = 174 min 4. Let's put together: 360 = - 22 174 = X X = 174*22/360= 10,6 min (- 10,6 to be correct) 5. For HW 0854 -18 + - 10,6 = -28,6 min. DONE!
Please remember that some people are starting from scratch. I would have been glad of this when I started; furthermore, I think it was quite rude of you to make a comment like that. If you can't say anything nice don’t say it at all
@@debbiebebington9803 believe me, if you put some effort to understand interpolation (which is not difficult at all) you will not have to deal with those graphic methods. Understand it just once and make your life so much easier
What happens when , like on page 37 of the Training Almanac for Victoria, you have a +0006 and a -0006, how do you work that one out ? Great answer previously though.
Fantastic video and well explained, I’ve always know them as crocodile graphs’
That's how we've been taught.. The crocks teeth!!
why is the difference altered by the time of day that high water ocurs? the tide dosent care what time it is, dose it?
The range of the tide and the time of high water and low water is not the same each day. These are driven by the relative position of the moon (and to a lesser extent the sun).
Fir example, here in Penzance tide time move forward by around an hour each day. When high water is around 06:00 and 18:00 (we have two high waters a day) we have spring tides and when high water is around 00:00 and 12:00 we have neap tides.
Spring tide having a larger range than neap.
The secondary port adjustment is different (generally greater) for spring tides compared to neaps.
We can therefore calculate the size of the adjustment based on the time of high water.
@@pzsc thank you. I thought it was unusal to make an ajustment for time of high tide. But its just an ajustment for spring or neap nothing unusual there. I was starting to think it was to do with the position of the sun.
Thank you these videos and the worksheets from your website are an excellent resource!
Do you have these secondary port templates available for download anywhere
You will find the sheets to download here pzsc.org.uk/shorebased/secondaryport/
OMG... those triangles are kind of kinder garden level.
Here is the adult method:
Calculating time difference for HW 0854
1. Difference between 0000 and 0600 = 360 min.
2. Difference between -18 and -40 = -22 min
3. Difference between 0600 and 0854 = 174 min
4. Let's put together: 360 = - 22
174 = X X = 174*22/360= 10,6 min (- 10,6 to be correct)
5. For HW 0854 -18 + - 10,6 = -28,6 min.
DONE!
Please remember that some people are starting from scratch. I would have been glad of this when I started; furthermore, I think it was quite rude of you to make a comment like that. If you can't say anything nice don’t say it at all
finally a explained formula without that drawing and scribbling nonsense! Thank you!!!
@@debbiebebington9803 believe me, if you put some effort to understand interpolation (which is not difficult at all) you will not have to deal with those graphic methods. Understand it just once and make your life so much easier
What happens when , like on page 37 of the Training Almanac for Victoria, you have a +0006 and a -0006, how do you work that one out ? Great answer previously though.
you literally picked the easiest time to do
Christopher Deane Thank you for the comment. Often this is the best place to start an learning sequence and then guide to harder questions later.