Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 27-01-2016, 13:20   #46
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,059
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by Mike1956 View Post
Having noticed a statement in a training booklet "Moon orbits the Earth over a 28 day cycle creating Spring & Neap tides" I emailed the publisher advising that a Tidal Cycle in fact averages 29 days, 12 hours, 44 mins & 3 seconds approximately. It is known as a Lunar month and does not vary much from this average and is never as little as 28 days. A google determined between the years 1760 and 2200 the shortest Lunar month is 29d 6h 34m and the longest 29d 19h 58m. Casual analysis of my tide table seems to confirm the above.

I was surprised when their reply strongly disagreed with my understanding and they went on to explain why....

The Tidal Cycle is due to an average of 3 cycles of the Moon.

Synodic Month 29.5 days
Tropical Month 27.5 days
Anomalistic Month 27.3 days

Average 28.1 days

I still feel my understanding is correct and have no comprehension of how the Tropical & Anomalistic would affect the Tidal Cycle.

I am sure someone on here will have a thorough knowledge of this subject and I look forward to reading replies.

Thanks

Mike
Mike, as I said earlier it is academic. What is your latitude what time of year is it and probably a doz. other variables. Get a tide chart for your location. Mine wouldn't be worth squat 50mi. up the coast. If that is not what you want to hear. Go get a degree in it. Probably all you will get here is practical advise.
__________________

__________________
Cadence is offline   Reply With Quote
Old 28-01-2016, 00:35   #47
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

[QUOTE=deblen;2028549]Maybe I am misunderstanding you.
In my area,there are two springs each "month" & two neaps.
One set of springs & neaps is "stronger" (full moon spring) than the other(new moon spring).QUOTE)

Just practising the QUOTE button.

When you are experiencing Spring tides we all are.

The Spring tides on a Full Moon do not always have a larger range.

Just picked my tide table up April 2015.

Full Moon 4 April Range of Tide +/- 4m

New Moon 18 April Range of Tide =/- 5m

Mike
__________________

__________________
Mike1956 is offline   Reply With Quote
Old 28-01-2016, 00:40   #48
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by jackdale View Post
Use the quote button to include a comment. You can delete portions that are not relevant.
Thanks, just having another practise.

Mike
__________________
Mike1956 is offline   Reply With Quote
Old 28-01-2016, 00:43   #49
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

[QUOTE=deblen;2028563]Attachment 117754

Attachment 117755

Attachment 117756

Attachment 117757

Here are tide graphs for Mar 2016 lunar cycle-from full moon to full moon.
Note the max. heights & max. lows vary each day. The highest high is about 3 days after full moon.Then there is a week of neaps,then a week of lower springs peaking about 3 days after new moon & then another week of neaps. QUOTE)

Hi Len,

The Lunar cycle as far as I am aware is from NEW to NEW moon. Not Full to Full.

Mike
__________________
Mike1956 is offline   Reply With Quote
Old 28-01-2016, 00:48   #50
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by Jdege View Post
What is usually left out of the grade-school explanations of tides is that how the gravity of moon pulls the oceans to make peaks under the moon and opposite to the moon, and troughs at 90 degrees on either side is true only in the southern ocean, where the oceans are free to flow 360 degrees around the globe.

Everywhere else, what we experience as tides are enormous low-frequency waves that propagate northward.

In the roaring forties, high tide is beneath and opposite the moon. Everywhere else, the timing of high tide is dependent upon how long it takes for the wave to propagate northward. At any given longitude, high tide is later the farther north you go.
Does this explain something I have been struggling to get my head round called "the age of the tide"?

Mike
__________________
Mike1956 is offline   Reply With Quote
Old 28-01-2016, 01:18   #51
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,712
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by Mike1956 View Post
Does this explain something I have been struggling to get my head round called "the age of the tide"?

Mike
Partially. But it's primarily local effects such as coastal friction and geography that determines "age".

Sent from my SM-G900I using Cruisers Sailing Forum mobile app
__________________
StuM is offline   Reply With Quote
Old 28-01-2016, 01:25   #52
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Tidal Cycle? Help me out here!

[QUOTE=Mike1956;2029028]
Quote:
Originally Posted by deblen View Post
Maybe I am misunderstanding you.
In my area,there are two springs each "month" & two neaps.
One set of springs & neaps is "stronger" (full moon spring) than the other(new moon spring).QUOTE)

Just practising the QUOTE button.

When you are experiencing Spring tides we all are.

The Spring tides on a Full Moon do not always have a larger range.

Just picked my tide table up April 2015.

Full Moon 4 April Range of Tide +/- 4m

New Moon 18 April Range of Tide =/- 5m

Mike
OK

Cheers/ Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 28-01-2016, 01:36   #53
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Tidal Cycle? Help me out here!

[QUOTE=Mike1956;2029032]
Quote:
Originally Posted by deblen View Post
Attachment 117754

Attachment 117755

Attachment 117756

Attachment 117757

Here are tide graphs for Mar 2016 lunar cycle-from full moon to full moon.
Note the max. heights & max. lows vary each day. The highest high is about 3 days after full moon.Then there is a week of neaps,then a week of lower springs peaking about 3 days after new moon & then another week of neaps. QUOTE)

Hi Len,

The Lunar cycle as far as I am aware is from NEW to NEW moon. Not Full to Full.

Mike
OK
I posted our tide tables for 4 weeks "mostly" in the month of Mar. 2016 as an example of a complete 4 week cycle of tides.
It is immaterial to me which day of the lunar cycle that I start with regarding tides. That is why we have tide tables-for those of us that need to know when hi or lo tide is on a particular day & are not interested in celestial mechanics

Cheers/ Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 31-01-2016, 00:27   #54
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by jackdale View Post
BTW - while searching around I came across this presentation from Canadian Hydrographic Service. Tide geeks might enjoy it.

https://www.acls-aatc.ca/files/abstract/MacAulay.pdf
Thanks for this, unfortunately my internet connection is so slow I am unable to open it. I mention this in case I ask any more questions that are answered within this document.

Mike
__________________
Mike1956 is offline   Reply With Quote
Old 31-01-2016, 00:30   #55
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by Cadence View Post
Mike, as I said earlier it is academic. What is your latitude what time of year is it and probably a doz. other variables. Get a tide chart for your location. Mine wouldn't be worth squat 50mi. up the coast. If that is not what you want to hear. Go get a degree in it. Probably all you will get here is practical advise.
Cadence, Sorry this thread seems not to be to your liking, I will try to do better in future.

Mike
__________________
Mike1956 is offline   Reply With Quote
Old 31-01-2016, 07:18   #56
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,059
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by Mike1956 View Post
Cadence, Sorry this thread seems not to be to your liking, I will try to do better in future.

Mike
Mike,

I wouldn't say the thread is not to my liking. It just has to many variables for
complete answer.

I hope the degree bit was not curt.


Cadence
__________________
Cadence is offline   Reply With Quote
Old 31-01-2016, 10:26   #57
Registered User

Join Date: Dec 2013
Location: SF Bay
Boat: 36' Hartog ketch
Posts: 30
Re: Tidal Cycle? Help me out here!

I think you misunderstood the question, or I didn't phrase it properly. I was referring to the 'king tides', like those that flood the Mill Valley interchange on a regular basis these days. (See the tides for next Sunday for example) When I was young, the extreme low tide was in the morning, and now they are in the afternoon. (Dad used to get us up at 2 or 3 in the morning to drive out to go clamming or ab picking.)

Ed
__________________
ThresherMan is offline   Reply With Quote
Old 31-01-2016, 10:50   #58
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,059
Re: Tidal Cycle? Help me out here!

Quote:
Originally Posted by ThresherMan View Post
I think you misunderstood the question, or I didn't phrase it properly. I was referring to the 'king tides', like those that flood the Mill Valley interchange on a regular basis these days. (See the tides for next Sunday for example) When I was young, the extreme low tide was in the morning, and now they are in the afternoon. (Dad used to get us up at 2 or 3 in the morning to drive out to go clamming or ab picking.)

Ed
Aren't the King Tides a result of the alinement of the Sun and the Moon. Not being an astronomer I would guess there is a period when earth, moon and sun align given the difference in day/year cycle and moon cycle?
__________________
Cadence is offline   Reply With Quote
Old 01-02-2016, 01:06   #59
Registered User

Join Date: Sep 2014
Posts: 114
Re: Tidal Cycle? Help me out here!

Too many posts in this thread now to keep track of but I assume King tides are just large Spring tides (high highs & low lows) which are due to more perfect alignment of Sun/Earth/Moon. With this forum being worldwide we are bound to come across terminology with which we are unfamiliar.

Note in September 2015 we had a Lunar eclipse ie perfect alignment and lo and behold we had the biggest Spring tides for +/-30 years and we will not see any bigger for the next +/- 30 years.

Mike
__________________

__________________
Mike1956 is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need help with tidal calculation and passage planning dokondr General Sailing Forum 7 31-03-2014 06:11
Tidal prediction freeware Hud3 Navigation 7 17-02-2008 08:15
tidal stream (direction) information pete33458 Seamanship & Boat Handling 15 08-08-2007 19:14
Tidal Prediction Website GordMay The Library 0 05-03-2006 06:42



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:28.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.