Drogues/parachutes - Page 4 - 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
  #31  
Old 06-05-2009
JomsViking's Avatar
Splashed
 
Join Date: Apr 2007
Posts: 552
Thanks: 28
Thanked 2 Times in 2 Posts
Rep Power: 8
JomsViking is on a distinguished road
Two problems with rigging it: Since the boat had no real strogpoints, so we used the cleats, but feeling they might not be strong enough, we rigged lines back to the winches which were stoutly mounted. This worked fine, however the bridle were chafing against the deck and gunwales. The lines seemed ok after the night passed, but if you looked closely you could tell that it was affected - hard to explain, no fraying or anything, but you just could tell that it had been affected in the area.
Retrieving it was "just" a lot of work with the winches, even though the cones captured cleats, winch-handles, and basically everything like that.

Quote:
Originally Posted by smackdaddy View Post
Cool Joms - then I'll humbly defer to your actual hands-on experience. This once. Mind you, not because I have a poster of the JSD above my bed like some - but because you have a big freakin' gun and squinty eyes...and have actually used the damn thing (the drogue - not the 44).

Anyway, was pulling the thing in a bummer? How'd you rig it?
__________________
Watch great footage about the story of one manís slow odyssey around the UK:
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
  #32  
Old 06-05-2009
shapka's Avatar
totally ok with it
 
Join Date: Nov 2008
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
shapka is on a distinguished road
Oceangirl and JomsViking:

From the JSD website:

3. A sea anchor cannot be designed to protect the boat. When tethered from the bow, the boat will yaw and develop unacceptable loads. The reason for this is that all boats must be designed to be directionally stable when moving forward - or it would not be possible to steer the boat. Therefore, if moving backwards, the boat will be unstable and will yaw and turn broadside to the sea.

Makes sense to me. Same idea as stern anchoring, no?

Dare I say center of areodynamic resistance is best downwind of the center of hydrodynamic resistance? All ducks in a row.

The reverse: boat lashing to and fro? And if one of the fros coincides with a drop or surf off the crest, big loads no?

Hoo boy. I will shut up now.
Reply With Quote Share with Facebook
  #33  
Old 06-05-2009
Senior Member
 
Join Date: Jan 2008
Posts: 287
Thanks: 1
Thanked 1 Time in 1 Post
Rep Power: 7
genieskip is on a distinguished road
Quote:
Originally Posted by oceangirl View Post
Not to sound like a toddler but..
Why? Why is it more likely to sustain damage when riding "bow-to" then "stern to"? Isnt the bow the strongest part?
I did go to JDS and read up(thanks for the suggestion) and it was very interesting, I was surprised how up to date he was, using hurricane IKE info/stats.

Sorry if I am beating a dead horse, thanks for taking the time to explain all this to a landlocked wish-I-was-back-on-my-boat Ocean Girl.

PS land dwellers are a strange lot
Erika
When a big wave hits you, you surge in the direction the wave sends you. If you are tethered by the stern you surge forward, the way boats are meant to go. If you are tethered by the bow, you surge backwards, and in big waves you do so very fast and hard. Your rudder can then be slammed against the stops if it is swung to one side, with great possibility of serious damage to it. That is the main problem with being secured from the bow.

The other problem is that a bow-on position isn't really bow on, it is really usually 45 degrees (at best) to the wind, a position that exposes much more of the vessel to the elements. We all know a boat at anchor sails from one side to the other, with shock loads at the end of each swing. That's why we have riding sails, but who wants more windage in a survival storm? When attached by the stern the aerodynamic qualities of most boats makes them much more like a weathervane that presents a much smaller cross section to the wind and waves. I would much prefer to face a breaking wave end-on (either end) than at any angle.

I am a belt-and-suspenders type person so I carry a parachute and a JSD, knowing that each situation is different and I can see a use for both. For example, if in the open ocean with lots of sea room I would go with the JSD but if there was land to leeward I would opt for the chute since that slows you down much more.
__________________
genieskip
Northeast
J40
1991
Reply With Quote Share with Facebook
  #34  
Old 06-05-2009
JomsViking's Avatar
Splashed
 
Join Date: Apr 2007
Posts: 552
Thanks: 28
Thanked 2 Times in 2 Posts
Rep Power: 8
JomsViking is on a distinguished road
Yes, that was our experience too. I would not compare it directly to stern anchoring, though. What we experienced was that we became "part of the sea" with the JSD, whereas when you are anchored to the stern you really would not want a breaking sea over the boat (except that you've chosen a really bad ancorage if that happens ). I'm not against anchoring at the stern, actually I'm thinking of adopting that, to prevent yawing, it's just that I feel that the two things only share a minimal subset of characteristica?

Quote:
Originally Posted by shapka View Post
Oceangirl and JomsViking:

From the JSD website:

3. A sea anchor cannot be designed to protect the boat. When tethered from the bow, the boat will yaw and develop unacceptable loads. The reason for this is that all boats must be designed to be directionally stable when moving forward - or it would not be possible to steer the boat. Therefore, if moving backwards, the boat will be unstable and will yaw and turn broadside to the sea.

Makes sense to me. Same idea as stern anchoring, no?

Dare I say center of areodynamic resistance is best downwind of the center of hydrodynamic resistance? All ducks in a row.

The reverse: boat lashing to and fro? And if one of the fros coincides with a drop or surf off the crest, big loads no?

Hoo boy. I will shut up now.
__________________
Watch great footage about the story of one manís slow odyssey around the UK:
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
  #35  
Old 06-05-2009
smackdaddy's Avatar
Last Man Standing
 
Join Date: Aug 2008
Posts: 12,951
Thanks: 80
Thanked 72 Times in 66 Posts
Rep Power: 8
smackdaddy is a jewel in the rough smackdaddy is a jewel in the rough smackdaddy is a jewel in the rough
Quote:
Originally Posted by genieskip View Post
When a big wave hits you, you surge in the direction the wave sends you. If you are tethered by the stern you surge forward, the way boats are meant to go. If you are tethered by the bow, you surge backwards, and in big waves you do so very fast and hard. Your rudder can then be slammed against the stops if it is swung to one side, with great possibility of serious damage to it. That is the main problem with being secured from the bow.
Genie - the rest of your post was great - but this part was a little off I think. People keep throwing this one around: that when chuting off the bow, the boat falls off the wave backwards with great force - slamming the rudder. Well if the chute is out there doing it's job you're only doing 1 knot leeward and waves are passing under you, just like with the JSD.

To be fair, if the above scenario were the case with a chute, then with the drogue in the same scenario the boat is going to fall forward off the wave and pitchpole.

So the rudder slamming argument doesn't hold up real well unless something has gone bad wrong. If the boat is being virtually held in place and the seas are passing under it as intended - one could make the argument that bow in is better for the rudder.

At the end of the day, if either of these devices is doing its job you're probably going to be in pretty good shape. Unless the monster falls on you. Then you're just screwed.

Last edited by smackdaddy; 06-05-2009 at 08:40 AM.
Reply With Quote Share with Facebook
  #36  
Old 06-05-2009
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 9 Times in 9 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
A couple of points that seem to be missed so far. While both a JSD and a Sea anchor tend to keep the boat from moving with any real speed, the JSD loads up proportionally, and has some give to it initially, depending on the loads and the speed the boat is moving at—a parachute sea anchor does not. When a breaking wave hits a boat tethered to a JSD, the JSD loads up progressively, slowing the boat more as more of the JSD comes under tension. This progressive loading allows the boat to rise with the wave and allows the JSD to pull the boat through the crest of the wave. A parachute sea anchor does not load progressively—it is either loaded or the rode is slack. If the rode is slack, there is a risk of the parachute collapsing or not re-filling properly. If the rode is loaded, then there is very little, if any, give to the connection, and the boat isn't allowed to rise with the wave, but is forced to get hit with the full force of it—rather than moving through it.

Also, most modern boats have far more buoyancy in the stern than they do forward, since the bows are normally fairly fine entry and on modern designs the beam is usually led pretty far aft. The stern will have a greater tendency to rise with the wave due to the greater buoyancy.

These two things, combined with the greater dynamic stability of a drogue deployed from the stern, mean that the JSD creates far lower shock loads and allows the boat to escape much of the damage that can occur when using a parachute sea anchor deployed from the bow.
__________________
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
  #37  
Old 06-05-2009
oceangirl's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Texas
Posts: 215
Thanks: 35
Thanked 8 Times in 8 Posts
Rep Power: 6
oceangirl is on a distinguished road
Series drogue?

Just talked with a fellow CD owner ( his is a 31 and mine is a 30), He deployed a drogue in 60-70 knot conditions. This drogue was the kind you can add more cones if you needed to (series drogue?). He attached it to the starboard stern cleat (with chafe protection) so his track was offset rather than straight down a wave. The drogue only slowed him down to around 6 -7 knots. He locked the helm midship and rode out the storm down below. He said he probably could of used another cone to attach to the series but didn't have one (he only had a single cone). His blow lasted a full 24 hours, during that time he never had a breaking wave in the cockpit or damage to the boat.

Thanks for all the input, I have definitely learned a lot
Erika
Reply With Quote Share with Facebook
  #38  
Old 06-05-2009
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
That's just a cone drogue, not a series cone drogue.

The difference is that one is a fairly large conical scoop with a springy hoop holding it open and some sort of gap at the end to let the collected water out.

A series drogue, by contrast, is many much smaller cones with a thick line running through them that can extend a couple of hundred feet behind the boat. The idea here is that the load or drag is distributed not at the end, but along the entire length of the line, and it is the cumulative effect that slows the boat. If the first type, due to wave action or just "whipping", leaves the water, your boat will speed up until the drogue "bites" again...lending to a big shock to your cleats/bollards. The series drogue, by contrast, is so freaking long that even if one part is clear of the water, another will be submerged and "biting", as its length is longer than the distance between wave tops.

I'm sure a bird following a boat with a JSD deployed would be tempted to land on the "clothesline" in the trough some hundred feet behind the boat...except for the occasional wave action!

I also concur with Genieskip that I would have both sea anchor and JSD. With a steel full keeler, I can heave-to Pardey style easier than some, and there's a time when I would want to creep at a knot to leeward for a few hours rather than run.
__________________
Can't sleep? Read my countdown to voyaging blog @
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by Valiente; 06-05-2009 at 10:38 AM.
Reply With Quote Share with Facebook
  #39  
Old 06-05-2009
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 9 Times in 9 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
oceangirl—

a jordan series drogue is usually 175'+ long and has upwards of 80 cones on it. The smallest one I've seen commercially available is 100 cones on 242' of line. Adding another cone or two makes very little difference... and not using a bridle basically defeats a large portion of the reasoning behind using a drogue.

__________________
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
  #40  
Old 06-05-2009
oceangirl's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Texas
Posts: 215
Thanks: 35
Thanked 8 Times in 8 Posts
Rep Power: 6
oceangirl is on a distinguished road
Yeah, that was the first time I'd ever heard someone not use a bridle, but it seemed to work for him. He did mention that a wave or two broke over his cabin top but his cockpit stayed dry, I thought maybe those were rogue waves coming from another direction.
Anyone else not use a bridle?
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



All times are GMT -4. The time now is 04:55 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.