Go Back   RIBnet Forums > RIB talk > RIBs & ribbing
Click Here to Login

Reply
 
Thread Tools Search this Thread
 
Old 20 June 2014, 11:57   #1
Member
 
jlandells's Avatar
 
Country: UK - England
Town: Swindon
MMSI: 235910561
Join Date: Oct 2013
Posts: 89
Tides for Lymington 26-06-2014

Hi All,

I may have an opportunity to go and play out of Lymington next week on Thursday so was doing a bit of prep and calculating tides. Usually, I'm pretty good at working out secondary tides etc, but this one has me baffled!

I have the following for Portsmouth for the day (which is the referenced Standard Port):

0338 1.1m
1039 4.3m
1557 1.2m
2252 4.5m

(all UTC, so still need converting to BST)

From the almanac, I calculated the HW offset for Lymington as -0085, giving me a HW time of 0914 UTC, or 1014 BST. I also calculated HW as 2.9m.

I was happy at this point, until I decided to verify my calculations!

EasyTide gives HW 1316 BST (2.9m)
VisitMyHarbour gives HW 1217BST (2.73m)
TidesPLanner App gives HW 1310 BST (3.0m)
Berthon Marina gives HW 1111 BST (3.0m)

I accept that tides are not precise calculations and I'm used to being out by a few minutes, but I'm seeing a difference of 1-3 hours here, which is potentially dangerous!

I've tripled checked my figures and calculations and have also checked for corrections to the Almanac, but keep coming back to the same times!

Can anyone help me to understand:

a) What the tide times will REALLY be on Thursday next week?
b) Where I've gone wrong with my calculations?
c) Why the information available online varies so much?

I've attached a scan of my secondary port calculation, in case the error is really obvious!

Many thanks,
-John.
Attached Files
File Type: pdf Lymington-26062014-Secondary.pdf (124.7 KB, 44 views)
__________________
jlandells is offline   Reply With Quote
Old 20 June 2014, 12:29   #2
gtb
Member
 
gtb's Avatar
 
Country: UK - England
Town: Southampton
Make: Ballistic 6.5
Length: 6m +
Engine: Evinrude 175hp ETEC
MMSI: 235 908 002
Join Date: Oct 2012
Posts: 240
I believe this is due to the fact that Lymington will have a double high tide at Springs, so you are both right

Some sites/tables will be giving you the time of the first high tide, and some like Easytide will be giving you the second (slightly higher) tide.

You can drop down from the two maxima on the Easytide curve to see the two answers (screen grab shows UTC). Maybe Berthon Marina is doing an average?
Attached Thumbnails
Click image for larger version

Name:	Screenshot from 2014-06-20 12:19:13.png
Views:	241
Size:	20.8 KB
ID:	95858  
__________________
gtb is offline   Reply With Quote
Old 20 June 2014, 12:33   #3
Member
 
jlandells's Avatar
 
Country: UK - England
Town: Swindon
MMSI: 235910561
Join Date: Oct 2013
Posts: 89
That makes sense. It's a shame that the tidal curve for Portsmouth doesn't reflect the double high, as this might have made it more apparent.

Many thanks,
-John.
__________________
jlandells is offline   Reply With Quote
Old 20 June 2014, 13:38   #4
Member
 
jlandells's Avatar
 
Country: UK - England
Town: Swindon
MMSI: 235910561
Join Date: Oct 2013
Posts: 89
Just had another look in my almanac. Guess it's time to read the pages titled "Special Tidal Curves from Christchurch to Selsey Bill"!

-John.
__________________
jlandells is offline   Reply With Quote
Old 26 June 2014, 17:56   #5
Member
 
Crusher's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Bubbas Bouy
Length: 7m +
Engine: Mercruiser
Join Date: Mar 2011
Posts: 629
RIBase
Hope you had a good day!!


Sent from my iPhone using RIB Net
__________________
Crusher is offline   Reply With Quote
Old 26 June 2014, 19:03   #6
Member
 
jlandells's Avatar
 
Country: UK - England
Town: Swindon
MMSI: 235910561
Join Date: Oct 2013
Posts: 89
Quote:
Originally Posted by Crusher View Post
Hope you had a good day!!

It was great - thanks to your guidance! Didn't expect to ache this much afterwards, though...!
__________________
jlandells is offline   Reply With Quote
Reply


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




All times are GMT. The time now is 20:44.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.