Sorry to add another question to the pot. As this is based on the effects of the moon, is it a full moon that these levels will/may be reached or at any phase of the moon could achieve these levels.
Spring tides occur at or around full moon. Spring tides are when you get the highest tide and the lowest tide, giving you the greatest tidal range. Maybe you should get a book?
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sorry ... see you have a book already. maybe you need a different book! /forums/images/graemlins/laugh.gif
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/forums/images/graemlins/laugh.gif yes, books abound. After reading Learn To Sail for Beginners progressed onto Basic Coastal Navigation (Frank J Larkin) New Edition.
After reading the latter for a couple of paragraphs, realised that although its reasonable reading, maybe we should have gone for the RYA reading material as it would be more relevant to the GB coast (assumption).
Hopefully when we have done double doubting ourselves we will get down to some serious sailing enjoyment. /forums/images/graemlins/cool.gif
The highest spring tides are a couple of days after full moon but fairly springish tides also happen around new moon. These are the times when the moon is aligned either on this side of the earth or the other.
Having done all this at Dayskipper we were then told that "round here the spring tides are those soon after lunch" - conversely neaps are early morning or supper time.
Cracked it now then /forums/images/graemlins/wink.gif
Yes double doubting will be good for us with navigation, we just need to ween ourselves off of it for the rest of our sailing.
@ MoodySabre
Cracked it now OMG!! now more confused than before /forums/images/graemlins/smile.gif What tides are the best to sail on neaps or springs ? or is that a mute point, like saying whats better an A road or Motorway.
Now as everyones early mornings, lunch and supper times, can you bracket it down a little bit for me say early mornings 6am till 8am lunch 12 till 2pm and supper 8pm till 10pm.
@ muckypup
Yes we sure will be. Currently running colregs of if its coming at us avoid it, if its coming anywhere near us avoid it. If necessary run aground knowing that they will then avoid us /forums/images/graemlins/smile.gif.
As I always found the 'twelths thing a pain I always use
1st hour 10% of range
2nd hour 15% of range
3rd hour 25% of range
4th hour 25% of range
5th hour 15% of range
6th hour 10% of range
The 'Hour is often more like one hour & 2 or 3 mins. & you do of course have to add or subtract the % of the range to/from high/low water.
I don't mean to teach you to suck eggs but I find it easier to work out in my head & the answers are very close to the twelths calculation.
What tides are the best to sail on neaps or springs ? or is that a mute point, like saying whats better an A road or Motorway.
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Still on the easy questions then /forums/images/graemlins/laugh.gif
A spring tide is higher at HW and lower at LW than a neap tide. As the tide goes out and comes back in over a similar period the spring tide has to travel quicker to shift more water.
So sailing with a spring tide will be quicker over the ground and sailing against it will be slower.
There will be more water over a sandbank at LW neaps than at LW springs but the converse at HW.
For further information please read the book /forums/images/graemlins/wink.gif
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Still on the easy questions then /forums/images/graemlins/laugh.gif
A spring tide is higher at HW and lower at LW than a neap tide. As the tide goes out and comes back in over a similar period the spring tide has to travel quicker to shift more water.
So sailing with a spring tide will be quicker over the ground and sailing against it will be slower.
There will be more water over a sandbank at LW neaps than at LW springs but the converse at HW.
For further information please read the book /forums/images/graemlins/wink.gif
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/forums/images/graemlins/laugh.gif I always like the easy questions as I find the answers more baffling than answers to the difficult questions.
/forums/images/graemlins/cool.gif I didn't know you had written a book, whats the title and ISBN /forums/images/graemlins/wink.gif. And will that give me the times as well. /forums/images/graemlins/grin.gif
None of these methods is right on the money, but close enugh is good enough.
And as the sea bed is not flat I always add or subtract half an hour anyway
After you complete your formal training, you're calculating the heights to two decimal places........
a few years later, you find yourself going.... urm... thats about 20cm..... 4 lots of that.... thats... say a metre...... urm... about half past two should do it.... /forums/images/graemlins/grin.gif
Hunson.... there is no sailing on the east coast without navigation.... you just learn to be happy until the sounder reads 0.1..... /forums/images/graemlins/grin.gif
After you complete your formal training, you're calculating the heights to two decimal places........
a few years later, you find yourself going.... urm... thats about 20cm..... 4 lots of that.... thats... say a metre...... urm... about half past two should do it.... /forums/images/graemlins/grin.gif
Hunson.... there is no sailing on the east coast without navigation.... you just learn to be happy until the sounder reads 0.1..... /forums/images/graemlins/grin.gif
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Indeed... Anyone calculating tides to 2 places (1cm) is asking for trouble. Tides don't read tide tables, and there are all sorts of effects that add or detract to / from the tide.... If you're happy taking £x,000 worth of boat with a little clearance, good luck to you.
Clearance between the bottom of the keel and the sea bed - I always think the ammount of safe water required depends on how desparate I am to get to mdestination and the nature of the bottom!