Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-02-2009, 13:22   #1
Registered User

Join Date: Dec 2008
Location: ontario canada
Boat: grampian 26
Posts: 1,743
Dangerous Quadrant

I keep hearing about the "dangerous quadrant" of a storm. What exactly is it and what makes it more dangerous than the other 3 quadrants. I am in the northern hemisphere if that makes a difference.
__________________

__________________
perchance is offline   Reply With Quote
Old 26-02-2009, 13:40   #2
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Being in the Northern hemisphere does make a difference, since the cyclone will be revolving anti-clockwise - in the Southern hemisphere they revolve clockwise.

GENERALLY Northern hemisphere cyclones will move Northwest, Southern hemisphere Southwest.

The dangerous quadrant is in front of the cyclone where the wind rotation will pull you in toward the centre, so in the North that would GENERALLY be the quadrant from Northwest to Northeast.

I say GENERALLY, because cyclones have also been known to zig-zag and move in all sorts of directions.
__________________

__________________
44'cruisingcat is offline   Reply With Quote
Old 26-02-2009, 13:48   #3
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Additionally, if the storm is moving toward you, it's speed is added to the wind speed (e.g., a 100 mph hurricane moving at 14 mph would have a total effective windspeed of 114 mph in the 'dangerous' quadrant).

Bill
__________________
btrayfors is offline   Reply With Quote
Old 26-02-2009, 13:56   #4
Registered User
 
svHyLyte's Avatar

Join Date: Mar 2006
Location: Tampa Bay area, USA
Boat: Beneteau First 42
Posts: 3,432
Images: 25
Google Buys Ballot's Law

Storm winds circulate around a center of low pressure because of the law of the conservation of angular momentum. In the northern hemisphere, that is counter clockwise. At the same time, weather systems move across the surface of the earth for several reasons. In the northern hemisphere, tropical lows tend to develop near the northern edge of the intertropical convergance zone and then typically curve around and travel in a north-easterly direction at some speed. The wind one observes on the earths surface is the "apparent wind" of the storm which is the sum of the low's speed of advance plus the speed of the wind around the low. The dangerous quadrant is that part of the circle of the storm's rotation where the aparent wind is a relative maximum. The "navitable circle" is on the opposit side of the center of rotation. See Buys Ballot's law - Wikipedia, the free encyclopedia
__________________
"It is not so much for its beauty that the Sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
svHyLyte is offline   Reply With Quote
Old 26-02-2009, 14:00   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2006
Location: Seattle
Boat: Cal 40
Posts: 2,401
Images: 7
Also the fetch, time the wind spends creating waves, is longer on the dangerous side, so the waves are bigger.

John
__________________
cal40john is offline   Reply With Quote
Old 26-02-2009, 14:21   #6
Long Range Cruiser
 
MarkJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,828
Images: 25
I haven’t been in a cyclone and I don't know how good my weather info would be in one.. but say its good.... How hard would one push the boat to windward to get out of the Dangerous Quadrant and into the Navigatable Quadrant?
I’ve always thought to try very hard and then put out the para anchor, not just dump the anchor in front of the cyclone.
One would also imagine it would be a bit rough and might be foreced to deploy the para anchor becasue of the waves beginning to break when the boat is still in the Dangerous Quadrant

Mark
__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 26-02-2009, 15:16   #7
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2006
Location: Seattle
Boat: Cal 40
Posts: 2,401
Images: 7
Quote:
Originally Posted by MarkJ View Post
I haven’t been in a cyclone and I don't know how good my weather info would be in one.. but say its good.... How hard would one push the boat to windward to get out of the Dangerous Quadrant and into the Navigatable Quadrant?
I’ve always thought to try very hard and then put out the para anchor, not just dump the anchor in front of the cyclone.
One would also imagine it would be a bit rough and might be foreced to deploy the para anchor becasue of the waves beginning to break when the boat is still in the Dangerous Quadrant

Mark
If you're trying to sail to the Navigable semicircle, that would be downwind.

Law of Storms found in many references calls for running with the wind on the starboard quarter (northern hemi) if you are in the direct path of the storm, wind increasing in strength, unchanging wind direction, falling barometer.

If you're in the dangerous semicircle, wind conditions above, but wind veering, they call for heaving to on starboard tack, which is pointing towards sailing away from the storm center (and away from safe semi).

I've always thought that I might try to continue to sail close reaching on starboard if possible before heaving to, to get further out from the storm.

Closest I've come, I hove to for a day to allow Ignacio to get ahead of me as I was due north of it, and at least at that point the weather service was saying that my destination and its possible was Hawaii.

John
__________________
cal40john is offline   Reply With Quote
Old 27-02-2009, 02:36   #8
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Quote:
Originally Posted by cal40john View Post
If you're trying to sail to the Navigable semicircle, that would be downwind.

Law of Storms found in many references calls for running with the wind on the starboard quarter (northern hemi) if you are in the direct path of the storm, wind increasing in strength, unchanging wind direction, falling barometer.
If you're in the dangerous semicircle, wind conditions above, but wind veering, they call for heaving to on starboard tack, which is pointing towards sailing away from the storm center (and away from safe semi)...
John
Published in 1876, Piddington’s Horn-book is the classic text on the subject.

The Sailor's Horn-book for the Law of Storms (being a practical exposition of the theory of the law of storms) ~ by Henry Piddington

The Sailor's Horn-book for the Law ... - Google Book Search
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 27-02-2009, 03:35   #9
Registered User

Join Date: Jan 2006
Location: London
Boat: Sigma 36
Posts: 27
cant outrun a depression

I often think about the best way to approach an oncoming depression, as in few months i'll be sailing east to west from the UK to Newport in the US... truth is that i dont think there is much you can do on the average cruising boat. I have a Sigma 36 and considering a forecast for several days ahead is not that reliable, trying to run away from a depression might not be worth it, after all the depression might change its course and you end up positioning yourself right on its path. A solid boat should withstand a north atlantic depression and I think it's important thinking about what sails you'll use and how easy it is to get them up in anger... and when to take them all down and just wait.

Marco.
____________________________________________
Read my blog and preparations at www.jamorph.com
__________________
Marco is offline   Reply With Quote
Old 27-02-2009, 04:03   #10
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
See also:
The Practical Encyclopedia of Boating ~ by John Vigor
specifically, ‘Hurricane Tactics’ (page 159) for a clear & concise explanation.

The Practical Encyclopedia of ... - Google Book Search
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 27-02-2009, 06:48   #11
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2006
Location: Seattle
Boat: Cal 40
Posts: 2,401
Images: 7
Quote:
Originally Posted by Marco View Post
I often think about the best way to approach an oncoming depression, as in few months i'll be sailing east to west from the UK to Newport in the US... truth is that i dont think there is much you can do on the average cruising boat. I have a Sigma 36 and considering a forecast for several days ahead is not that reliable, trying to run away from a depression might not be worth it, after all the depression might change its course and you end up positioning yourself right on its path. A solid boat should withstand a north atlantic depression and I think it's important thinking about what sails you'll use and how easy it is to get them up in anger... and when to take them all down and just wait.

Marco.
____________________________________________
Read my blog and preparations at www.jamorph.com
This hasn't been about outrunning storms or extended weather forecasts. It's been about trying to position yourself based on observed local conditions to try to reduce the effects of the storm. Sometimes it will do no good. Changing your position 50-100 miles relative to a 300 mile diameter hurricane could make a big difference in the conditions experienced. Positioning yourself relative to a 600 mile diameter extra tropical storm moving fast might make less difference.

John
__________________
cal40john is offline   Reply With Quote
Old 27-02-2009, 07:18   #12
Registered User

Join Date: Jan 2006
Location: London
Boat: Sigma 36
Posts: 27
a lot depends on the boat

Quote:
Originally Posted by cal40john View Post
This hasn't been about outrunning storms or extended weather forecasts. It's been about trying to position yourself based on observed local conditions to try to reduce the effects of the storm. Sometimes it will do no good. Changing your position 50-100 miles relative to a 300 mile diameter hurricane could make a big difference in the conditions experienced. Positioning yourself relative to a 600 mile diameter extra tropical storm moving fast might make less difference.

John
Hi John, sorry i might have misunderstood, but my point is really that on my boat I would sail so slow compared to how fast the centre of the depression or cyclone is moving that doing anything specific will only change the ordeal by little, i would concentrate on sea state and which way to ride it out with the boat in one piece. I think different boats respond differently to different sea states. I've never been in the situation, but i would not run with my boat, I would heave to beyond a certain point, or go bare poles with or without a sea anchor/drogue. My boat has pinched ends and is quite beamy, she tends to round up (and risk to be rolled) if i tried to run downwind... She is more manageable when at 70 deg to the wind than downwind, and this would give me more of a fighting chance... it would be totally different on an OPEN 60, there you'd run and run reducing sails or even under bare poles...

Marco
blogSTAR
__________________

__________________
Marco is offline   Reply With Quote
Reply

Tags
danger

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
St Vincent - Dangerous for Cruisers Hud3 Cruising News & Events 47 16-01-2009 14:54
Dangerous marine species around the world Whimsical Fishing, Recreation & Fun 4 20-08-2008 07:54
Dangerous Overheat? brianontheroad Engines and Propulsion Systems 13 29-07-2008 02:50
Bungee's ARE dangerous! delmarrey The Sailor's Confessional 35 10-01-2008 05:11
Just getting started- read a dangerous book Don't Panic Meets & Greets 8 11-10-2007 11:43



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:29.


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.