Battening down for heavy weather - Page 7 - 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 > Skills and Seamanship > Seamanship & Navigation
 Not a Member? 

Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


Reply
 
LinkBack Thread Tools
  #61  
Old 03-17-2007
Member
 
Join Date: Nov 2006
Location: Beacon, New York
Posts: 652
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
Tartan34C will become famous soon enough
I read the information available on the design and use of the Jordan series drogue. The first few times I went though the information I was left with the impression that the tow line attached to a boat had a strain that was determined by the total area of the drag and the speed it was pulled though the water. The drag force was independent of how the area was distributed among the elements so a single cone with a frontal area of 5 square feet placed the same strain on the tow line as a series drogue with a total of 5 square feet distributed between all the individual elements.

After reading it again I see that Jordan has discovered some interesting information about how the force is transferred to the boat over the total time the wave is passing the boat. In other words the rate of transfer or the distribution of the amount of force over the time of the wave cycle is important and not necessarily just the total force.

A single element at the end of the tow line went slack during the wave cycle and because of stretch in the towline didnít have an immediate effect when the cycle started again. And when the line finished stretching, the shock load was larger then with the series drogue. The total force transferred stayed the same in each case but when and how it peaked was different.

Also the construction difference between a parachute drag device and series drogue was interesting. During the slack time the parachute device might collapse and tangle and the shock from the sudden opening lead to an early failure of the parachute device. The series drogue on the other hand had some elements closer to the boat so they started to develop drag early in the cycle without the shock or extra time needed to take out the stretch in the line. As the cycle continued more elements came into play increasing the force in the line gradually and in step with the amount of correction needed to keep the boat square to the wave face.

The only question now is why not just tow lines instead of a drag device. It seems that a Jordan will replace the helmsman while towing lines just slows the boat and still requires a helmsman to keep the boat from broaching. I consider my windvane to be the best helmsman on board and I donít feel any need to replace that helmsman.

After everything is said and done my plan is to stay on course until reduced sail is not sufficient for comfort or safety and then I will heave-to assuming that I have a suitable boat. Next step for me is to lay-a-hull and running is a last resort unless running is also my intended course to destination and in that circumstance I would have stayed on course until under bare poles and then I would tow lines and let the windvane handle things. The Jordan is a great idea but I donít want to carry a single purpose device that will be seldom if ever used unless I absolutely need to. Of course I carry a liferaft and thatís a single purpose device that I hope to never use but I donít have an alternate plan that doesnít require one. With a suitable boat I think running with lines to control speed is a reasonable plan for me. If you have a multi-hull or a fast fin keel boat then a Jordan series drogue would be a great investment.
All the best,
Robert Gainer
Reply With Quote Share with Facebook
  #62  
Old 03-17-2007
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Many fin keel designs won't heave to very well, and will either make a lot of leeway or forereach. My boat, being a multihull, is one that doesn't heave to particularly well. This is one reason I decided to invest in a JSD.
__________________
Sailingdog

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

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

óCpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

StillóDON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #63  
Old 03-17-2007
Valiente's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Toronto
Posts: 5,491
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
Valiente has a spectacular aura about Valiente has a spectacular aura about
Quote:
Originally Posted by Tartan34C
. With a suitable boat I think running with lines to control speed is a reasonable plan for me. If you have a multi-hull or a fast fin keel boat then a Jordan series drogue would be a great investment.
All the best,
Robert Gainer
Robert, from the storm tales you've told here, I think you are among the few people qualified to make that decision. And ultimately, that's the joy and the misery of being the skipper: it's your call how to run the boat in the best interests of staying alive and in one piece. Towing warps and even old chain and tires has worked in the past on various boats, and has notably failed to work at all in others (not to mention that some warps can foul the rudder, vane or prop if not watched). Same with lying ahull...some boats can wallow comfortably...others will "death roll". In reading the recent book "Rescue in the Pacific" (which was educational and horrific at the same time), a number of techniques were tried with varying degrees of success, but the boats that lived seem to have the deepest "bag of tricks" to keep the stick in one piece and the crew unbroken. Fatigue and anxiety seemed to be the biggest hazards, but it takes a certain level of experience and faith in one's judgment to leave it all up to the vane and the trysail and to retire below for the rest one MUST have if one is to survive a three-day heavy gale. Because just trying to steer through it will kill the average crew, it seems, or cause them to make fatal or disasterous calls.
Reply With Quote Share with Facebook
  #64  
Old 03-17-2007
Valiente's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Toronto
Posts: 5,491
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
Valiente has a spectacular aura about Valiente has a spectacular aura about
Quote:
Originally Posted by sailingdog
Many fin keel designs won't heave to very well, and will either make a lot of leeway or forereach. My boat, being a multihull, is one that doesn't heave to particularly well. This is one reason I decided to invest in a JSD.
These devices seem particularly suitable for cats, although (pun intended) it would be a drag to deploy them correctly (maybe a trip line?). I would also want aft cleats or extrusions of extremely beefy construction and backing were I to drag any type of drogue or warp from a catamaran or a trimaran's hulls.

But I bet they might save a cat from "taking flight" down a steep wave face.
Reply With Quote Share with Facebook
  #65  
Old 03-17-2007
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Valiente-

My boat is a trimaran, and yes, I believe the JSD will prevent the boat from surfing down the face of a wave. I would hesistate to use a trip line, since I've seen some problems where a trip line would foul the drogue, and that is to be avoided at all costs. The attachment points I am using are two heavy chainplates bolted to the sides of the central hull, which are installed for this specific purpose.
__________________
Sailingdog

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

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

óCpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

StillóDON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #66  
Old 03-17-2007
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,625
Thanks: 2
Thanked 89 Times in 87 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Robert-
"The only question now is why not just tow lines instead of a drag device."
I'd expect that the Jordan device creates more drag in less space, i.e. you can stow a Jordan device in a lot less space than the amount of lines you would need to tow for the same effect. Lines don't have much drag, compared to cones.
Reply With Quote Share with Facebook
  #67  
Old 03-17-2007
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
The other reason is that a Jordan Series Drogue creates resistance that increases at a predictable rate. The greater the force on the drogue, the more cones that become active in resisting the load as the drogue line straightens out.
__________________
Sailingdog

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

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

óCpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

StillóDON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #68  
Old 03-17-2007
Valiente's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Toronto
Posts: 5,491
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
Valiente has a spectacular aura about Valiente has a spectacular aura about
Quote:
Originally Posted by sailingdog
Valiente-

My boat is a trimaran, and yes, I believe the JSD will prevent the boat from surfing down the face of a wave. I would hesistate to use a trip line, since I've seen some problems where a trip line would foul the drogue, and that is to be avoided at all costs. The attachment points I am using are two heavy chainplates bolted to the sides of the central hull, which are installed for this specific purpose.
Yes, I was thinking more of a cat. With a tri center hull, you don't have so much beam, but you do have a place to put serious attachment points...within reach, so you don't need a trip as you might with 18 feet between hulls
Reply With Quote Share with Facebook
  #69  
Old 03-18-2007
Member
 
Join Date: Nov 2006
Location: Beacon, New York
Posts: 652
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
Tartan34C will become famous soon enough
Quote:
Originally Posted by hellosailor
Robert-
"The only question now is why not just tow lines instead of a drag device."
I'd expect that the Jordan device creates more drag in less space, i.e. you can stow a Jordan device in a lot less space than the amount of lines you would need to tow for the same effect. Lines don't have much drag, compared to cones.
Yes and thatís my point. But different boats behave differently running side by side in the same storm. And different parts of the world have different wave shapes.

A catamaran or trimaran and a fast fin keel boat share something in common compared to my current boat, a Tartan 34C. They can sail under bare poles fast enough to lose control with enough wind. They also displace less then the same size full keel boat. I think you want to slow them down quite a bit and the Jordan Series Drogue is the safest way to do that while putting the least shock on the boats structure when you are talking about a light boat. Remember the strain on the drogue is a percentage of the boats weight so a light cat will have a smaller strain on the system then a full keel boat of the same length. With my all up displacement I might have a strain of 12,000 on the Jordan Series Drogue and thatís unacceptable to me.

Also I think in terms of staying square to the wave face while running and I want to slow the boat down but not as much as the Jordan Series Drogue would. If you slow down too much you will lose water flow over the rudder when the waves crest passes and at the wave top you have the greatest effect from the wind. I think itís a mistake to be in a part of the cycle with the greatest wind effect and the least available steering force. My plan is to keep enough boat speed to have positive steering at all points in the wave cycle. So I want less drag and more control. I also have a center board which will act like the feathers on an arrow when it is down just a little bit. The publications I looked at including the paper written by Jordan all seem to agree that being rolled while running is connected to losing control and broaching. The speed doesnít scare me as much as the broach does. You can avoid a broach by having enough drag to keep the stern to the seas or slow the boat and steer. I have confidence in my windvane and because a random wave will have the same effect on the boat using either system I will use lines as a drag.

My thinking also includes the fact that seas breaking aboard in the cockpit and cabin area are not a good idea. I think, and this is just an opinion that adding 12,000 pounds to the stern will hold the stern and makes it a target for the seas instead of having just 5,000 pounds which will more easily let the stern rise to the waves. I have had seas sweep the boat and itís not any fun. I want to avoid that in the future.

I sail in the North Atlantic now and if I wanted to travel in the southern oceans I would approach this differently. Pitch poling is a greater risk there because the fetch permits a larger and steeper wave. I also see a connection between boat sizes and being pitch poled. If I wanted to sail under those condition I would select a larger boat then I have now and because the line pull from Jordan Series Drogue as a percentage of displacement decreases as boats get larger I would consider adding one then. The lose of boat control at the wave crest is also a problem that becomes less as the boat gets larger because of the increased inertia a larger boat has. She will keep moving unless she hits something solid.

Lots of variables and permutations make for lot of solutions available to the skipper. Whatever plan you select you need to keep in mind that changing plans after things get really bad is usually a very bad idea. And one limiting factor is that if you didnít bring it you donít have it. So if you think you might want to try a Jordan Series Drogue donít forget to pack one. I already carry lots of heavy line so I am prepared to implement my plan, and my backup plan, and then my fall back plan. And if all else fails I can switch to my ultimate plan.
All the best,
Robert Gainer
Reply With Quote Share with Facebook
  #70  
Old 03-19-2007
Owner, Green Bay Packers
 
Join Date: Sep 2006
Location: SW Michigan
Posts: 10,318
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12
sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice sailaway21 is just really nice
A wry sense of humor is a rare and wonderful thing. Thx, Rob't.
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
Weather Information Sources Michael Carr Seamanship Articles 0 09-16-2000 08:00 PM
The Weather Triangle Michael Carr Seamanship Articles 0 08-17-2000 08:00 PM
How to Sail with Weather Bob Rice Seamanship Articles 0 04-21-1999 08:00 PM
Weather Forecasts for Sailors Michael Carr Seamanship Articles 0 08-31-1998 08:00 PM
Gathering and Using Weather Information Michael Carr Seamanship Articles 0 03-31-1997 07:00 PM


All times are GMT -4. The time now is 05:45 AM.

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.