Angle of Vanishing Stability - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Like Tree7Likes
Reply
 
LinkBack Thread Tools
  #11  
Old 12-06-2011
Senior Member
 
Join Date: Mar 2006
Location: VA
Posts: 2,025
Thanks: 1
Thanked 3 Times in 3 Posts
Rep Power: 9
PalmettoSailor will become famous soon enough
Far more people leave their boats upright and floating than find themselves upside down.

Seems we tend to worry about our imagined worst cases and can't quite grasp that WE are the weak link in most cases.
Faster and jameswilson29 like this.
__________________
PalmettoSailor
s/v Palmetto Moon
1991 Catalina 36
Reply With Quote Share with Facebook
  #12  
Old 12-06-2011
shaile's Avatar
Junior Member
 
Join Date: Dec 2009
Posts: 20
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
shaile is on a distinguished road
Quote:
Originally Posted by peterchech
I often wonder about what you do if you are in the cockpit when the boat rolls. If you are tied in (you should be), you may be held under for some time before the boat comes back up especially if sheets are not released in time or if wave/wind action coincidentally holds the boat inverted longer than would be expected. If you cut away from the tether to get to the other side of the boat, you risk being separated and lost at sea. Webb Chiles talks about being rolled twice in the southern ocean on one of the "furled sails" podcasts, but he was in the cabin both times and the boat came right back up. I think I would be tempted to throw out a sea anchor and hide below if the going got really rough, but that isn't always an option and often it is a rogue wave that breaks unexpectedly which rolls the boat
.

That's exactly the situation I thought of when I raised the subject.
Many boats have AVS below 140 degrees which, according to the book, means that they would incline to stay up side down for several minutes once rolled over. In this time the boat might take water, something that would worsen the situation .
Reply With Quote Share with Facebook
  #13  
Old 12-07-2011
Faster's Avatar
Just another Moderator
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 14,699
Thanks: 68
Thanked 197 Times in 189 Posts
Rep Power: 10
Faster has a spectacular aura about Faster has a spectacular aura about Faster has a spectacular aura about
Quote:
Originally Posted by midlifesailor View Post
Far more people leave their boats upright and floating than find themselves upside down.

Seems we tend to worry about our imagined worst cases and can't quite grasp that WE are the weak link in most cases.
Agreed... in most cases I think even the 'crappy' boats will take more than most of us when push comes to shove....
__________________
Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Reply With Quote Share with Facebook
  #14  
Old 12-07-2011
grumpy old man
 
Join Date: Apr 2011
Posts: 3,650
Thanks: 1
Thanked 74 Times in 70 Posts
Rep Power: 4
bobperry will become famous soon enough
Midlife:
I totally agree with you but that's a hard factor to graph.
__________________
Please visit my blog. It's fun to read.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Bob's Blog ....

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Please also visit my new web site
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #15  
Old 12-07-2011
Senior Member
 
Join Date: Mar 2006
Location: VA
Posts: 2,025
Thanks: 1
Thanked 3 Times in 3 Posts
Rep Power: 9
PalmettoSailor will become famous soon enough
Quote:
Originally Posted by bobperry View Post
Midlife:
I totally agree with you but that's a hard factor to graph.
Yeah, but there's a bunch of photographic evidence on this site of people risking life and limb abandoning boats that didn't appear to be in immediate danger of sinking.

Since the rigs are on those boat were intact, and these boats don't seem to be in danger of sinking, loss of steering could be a possible factor. If you can't control the boat, you have no ablity to get yourself out of the situation but from the threads I see, it seems folks headed to the briny blue worry more about getting upside down than how to steer the boat if the rudder snaps off.
Jeff_H, Faster and Agri like this.
__________________
PalmettoSailor
s/v Palmetto Moon
1991 Catalina 36
Reply With Quote Share with Facebook
  #16  
Old 12-08-2011
shaile's Avatar
Junior Member
 
Join Date: Dec 2009
Posts: 20
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
shaile is on a distinguished road
Quote:
Originally Posted by peterchech View Post
However the flush deck, and relatively low ballast to displacement ratio might make recovery from turtle much less likely, ...
Tying an inflatable boat on top of the coachroof or on the foredeck should lower the inverted stability of the boat, but is it significant ?

Anybody knows how to calculate it ?
Reply With Quote Share with Facebook
  #17  
Old 12-08-2011
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,706
Thanks: 12
Thanked 104 Times in 99 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Quote:
Originally Posted by shaile View Post
...We can take this idea a step further and install a balloon on deck. Such a balloon can be empty in normal sailing and automatically inflated when the boat is inverted. If this idea is right, I suppose I would have not been the first one to raise it. So why don't we see such systems on boats ?...
Among other reasons is the fact that roll-overs are quite rare and those that do occur, usually do so in conditions that are so violent that the yacht is quickly rolled up-right anyway. Moreover, it would be difficult to implement such a solution in a cost effective manner. Further, you have evidently not spent any time at sea in rough conditions. In such, it is not uncommon to have the entire deck all but submerged. A hydrostatic release might/likely would have a difficult time distinguishing between an immersion and an inversion, and all one needs at such times is an inflation device exploding open to add to the difficulties. (If you read/review Rousmaniere's "Fastnet Force 10" you will discover that more than one crew had to hack up/cut away their life-raft when it inadvertently inflated in the cockpit at the height of the storm, hazarding everyone in sight.)

As for an inflatable tied down on deck, it would be a foolish person indeed that would add such windage and such a target for a breaking sea on deck in all but relatively benign conditions.

FWIW...
__________________
"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."
Reply With Quote Share with Facebook
  #18  
Old 12-08-2011
Senior Member
 
Join Date: Mar 2008
Posts: 886
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 7
GaryHLucas is on a distinguished road
I liked the comment that came out of the Fastnet disaster "The safest way to enter your life raft is to step UP into it!"

I've always thought real blue water cruisers should have seat belts down below. So when you really want your mommy you could just buckle in and wait for everything to stop moving. The Fastnet proved that most of the people lost would have survived if they had seat belts!

Gary H. Lucas
Reply With Quote Share with Facebook
  #19  
Old 12-08-2011
svHyLyte's Avatar
Old as Dirt!
 
Join Date: Nov 2008
Location: Tampa Bay Area
Posts: 2,706
Thanks: 12
Thanked 104 Times in 99 Posts
Rep Power: 6
svHyLyte is on a distinguished road
Quote:
Originally Posted by GaryHLucas View Post
I liked the comment that came out of the Fastnet disaster "The safest way to enter your life raft is to step UP into it!"

I've always thought real blue water cruisers should have seat belts down below. So when you really want your mommy you could just buckle in and wait for everything to stop moving. The Fastnet proved that most of the people lost would have survived if they had seat belts!

Gary H. Lucas
As a matter of fact, we have a seat-belt at the navigation table that was salvaged from a 1963 Chevy. It works a treat to keep one in place in rough conditions albeit, sometimes rough on the mid-section, eh? (My wife wants me to add them to the heads!)

FWIW...
__________________
"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."
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
tacking angle mr31 Racing 22 05-23-2012 12:32 PM
Best angle to windward? malyea Racing 9 12-07-2010 02:46 PM
Angle of Vanishing Stability Grampian 30' 1974 akin_alan General Discussion (sailing related) 9 09-07-2010 04:42 PM
Bayfield 29, angle of vanishing stability celiro Sailboat Design and Construction 2 11-29-2007 05:19 PM
AVS - angle of vanishing stability stravaigin General Discussion (sailing related) 7 06-20-2007 12:55 PM


All times are GMT -4. The time now is 11:19 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.