When hit by a breaking wave in really nasty conditions, it will NOT be confined to the aft or the bow of the boat. It will probably also be a freak that comes from an unexpected direction, thus you might take it in the cockpit when using a chute (or viceversa). The weakest point on many yachts are the cabin, and a breaking wave that smashes the cabin top is going to ruin your day
Talking about strenght, the bow and deck structure in the fore-triangle will probably be a little stronger than the cockpit, and the cockpit will contain a lot of water, but if you have a moderate size cockpit with a bridgedeck the difference should be negligible?
You MUST avoid breaking waves, and the JSD is probably the best device, yet, to ensure that. In non-breaking conditions a chute might be great, especially if you want to avoid a lee shore.
If you read Adlard Coles (my copy is rather old) there's evidence of streaming warps and using chutes, with no clear conclusion on what works. IIRC his conclusion were that "it depends" however many of the chutes broke their attachment points and lines. This is another thing that I do not like about chutes, the MASSIVE forces that they apply to the vessel, which the JSD or toher warps do not do to the same extent.
Yeah Joms - I've got that book - AC's Heavy Weather Sailing 6th Edition put together by Peter Bruce. There's an entire chapter dedicated to the Pardey-style chute set up.
You are, of course, spot on that the whole point is to avoid breakers. And that waves can come from virtually any direction. Now whether the JSD allows you to actually AVOID those breakers might be another point of discussion since there's apparently no active steering with it.
Regardless, my hunch is that most people like me (i.e. - those that have an interest in the subject - but have no experience with it yet) initially intuitively lean toward the bow-on approach to heavy weather simply because that's the way boats are "designed to go". That's where the strength seems to be.
So, boiling it down to the above question helps shed some light on this perception (disregarding the devices altogether) and whether it has validity - all things equal.
At the end of the day, it seems to me that we need to keep this an objective discussion. That Lynette chick got a pretty good beatdown with the demand that she only provide info for which she had definitive data to back it up. That's cool I guess because she was a sales person - but that same standard should be applied here if we are going to make "definitive" statements about one device over another.
Personally, I think both have their pros and cons. And, to your point, that's why there are no real conclusions one way or the other. Hence, the reason "definitive" statements seem a little suspect.
(PS - so we've established that the bow of the boat has more strength, so what about the rudder issue in the scenario?)
Last edited by smackdaddy : 06-09-2009 at 01:27 PM.
Yeah Dog - that was your statement and I now understand the clarification above. BUT - you're still making some "definitive" statements that, all things equal, don't quite make sense. For example:
1. Your bolded statement that a chute anchor "doesn't yield at all" doesn't make sense. The HWS books I've read say that you do get 1-2 knots of leeward motion with a chute. Didn't you say that the JSD gives you essentially the same relative leeward speed (1-2 knots) - thereby "negating the need for steering and allowing the crew to drink heavily down below" (paraphrasing here) - again, like the chute? I do understand your point about the advantage of progressive loading of the JSD - and that makes a lot of sense. But not this other stuff.
2. Next, your statement "That doesn't even include the damage to the steering gear that can occur to a boat that is bow to seas." doesn't quite hold up either. First, this is only true IF the chute rode gets enough slack (as Genie mentioned) for the boat to "fall" back off a wave with enough force to damage the rudder. Though this assumption is certainly theoretically valid - I've not seen or read a lot of evidence that it's a widespread problem if the deployment is done correctly (which is another issue). Again, the chute technique IS in all of the HWS books I've read. And a lot of people seem to swear by it.
When the JSD isn't under a load, it effectively hangs straight down from the transom of the boat... since the terminal end is weighted... under varying loads, it will have the portion nearest the boat horizontal and then curve downwards. As it loads up, more of it will come under tension and horizontal, and it will straighten out loading progressively as more cones become actively involved in resisting the tension.
The parachute sea anchors are binary devices—either they're under load or they're not. The shock loading that occurs when a boat loads a parachute anchor is a sudden, one time thing, rather than the progressive loading seen with the JSD. Until the rode tightens completely the boat is free to move, unlike what happens with the JSD, where the rode is loaded to some degree all of the time.
Quote:
Now that brings us to the original question above - which is still open - and which comes into play with your statement about the "serious damage" incurred if a boat is bow-on...
3. If the boat does NOT fall off the wave - and is effectively held in place with 1-2 knots of leeward motion - and is hit with a 20 knot breaking wave, which end of the boat takes that breaking wave with less serious damage?
If the wave hits the bow and breaks, the boat is far more likely to be rolled than if the boat is hit while lying stern to the breaking wave. This has been proven in USCG tank testing... Even if the cockpit is damaged a bit, the damage is likely to far less than if the boat is rolled.
As for avoiding breakers, it really isn't possible to avoid them intentionally. That only happens with great luck. However, if you read anything about the JSD on the website I've linked previously, you'd understand that the JSD is designed to help a boat survive a strike by a breaking wave. It would seriously help if you stopped trolling and actually went and did some reading on the Jordan Series Drogue website... which has a lot of good information you've obviously never bothered to read.
__________________
Sailingdog 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.
—Cpt. Mal Reynolds, Serenity (edited)
If you're new to the Sailnet Forums... please read this POST.
Good information on the JSD website? Oh, you mean like this:
"Conventional storm survival lore and literature is no longer necessary or pertinent. Whenever the situation deteriorates to the point where further progress is no longer possible or even when it becomes unpleasant, the logical choice is to ride to the drogue until conditions improve. This also applies in the event of crew fatigue, illness, or the need for a stable platform to permit rigging repair.
Although the drogue was developed using sophisticated engineering tools and procedures, the device itself is very low tech. There are no special materials, no moving parts or controls, no special hydrodynamic shapes. The only material subjected to high loads is the double braided nylon rope. It is poignant to realize that every sailing vessel which went to sea from the time of the Romans had on board all the materials and skills needed to build a drogue which would have been capable of bringing the ship safely through a survival storm. They had strong hawsers used for anchoring, spare sail cloth for sail repair, and a sailmaker with the skill to fabricate the cones.
With the help of the drogue; St Paul on his biblical voyage across the Great Sea could have safely made passage to Rome instead of being shipwrecked in the wilderness, and the spread of Christianity would have taken a different course. The settlement of the American continents might have been advanced by 400 years if the Vikings had the drogue. Their vessels, although ideal for fast coastwise voyaging, were hopelessly unsafe on the open sea under storm conditions. Since they were undecked, they could not lie ahull without swamping, and if they tried to run off they would surf and plunge into the next wave. The Viking ships had no structural bulkheads and would have split open like a pea pod on impact with the green water in the preceding trough.
With the help of the drogue, the Vikings might have been able to support their colonies in the New World.
So much for conjecture!"
++++++
I love that last part. Sounds like the Gibraltarian you like so much.
Look, Dog I'm not "trolling". You really need to harden up and stop crying troll every time someone presents an alternative view.
I've never said the JSD is a "bad" device. But I do think saying stuff like it would have helped the esteemed Viking, St. Paul, spread Christianity to America is a little rich.
It's marketing dude. Marketing. Look at all the wonderfully positive things the para-anchor site says about it's product. Are you agreeing with JSD that we can now throw out all other "conventional wisdom" regarding storm tactics and use ONLY this device...always...no questions?
Can you provide a link to the CG study you cite? That would be helpful. If you recall, the one on the JSD site talks about the F/V "Fair Wind" lying stern-to and getting pitch poled on page 2 (sounds like serious damage to me). But, of course, that report was testing drogues and stern-to orientation - so it had an obvious slant.
Last edited by smackdaddy : 06-09-2009 at 03:17 PM.
Smack and SailingDog,
While I personally believe that the JSD is a great device, and that a traditional chute is a bit binary (as Dog mentioned), there's no disputing that several people in several boats has had great success with both (and the opposite). Our biggest problem is probably that all the assumptions we've traditionally made when it comes to the sea, are basically skewed. "Engineers" typically laughed at sailors when they talked about freak waves, and showed them using their LINEAR models that it was impossible, however sattelites showed that they DO exist, and are more common than we could hope for. Also the life expectancy of large vessels were sometimes grossly wrong, again because the models we had were imprecise.
My point is that we're at a stage where we know that we don't know enough - there's so many parameters that we cannot simulate, nor test the possibilities, hence we must trust experience and our guts. We do have some empirical data, though, and the JSD/USCG testing is probably the best we have?
__________________
I had the ambition to not only go farther than man had gone before, but to go as far as it was possible to go.
-Captain Cook, on his voyage to the Pacific in Endeavor
Good point Joms. I think you nailed it. "We know that we don't know enough." I agree 110%. That's why I don't think definitive statements are quite ready for prime time. In addition to your linear wave model example, think about how many times medical studies have done a 180.
I do concur that the JSD/USCG testing is a very good basis for data regarding drogues. But because it is such - it makes you wonder if the statement in paragraph 6.6 about sea anchors off the bow is meant to be a definitive proclamation - or meant to position the intent of the report; that it is about drogues not sea anchors. That's why I'm interested in the other report Dog mentioned.
As far as drogues go, I personally don't think there's much room for argument. The JSD rocks. But then you have people like the Pardey's who went through 20 gales/storms that required various storm tactics - and did a good amount of testing the sea anchor chute specifically in actual HW conditions (not tanks and computer models). The sea anchor thing worked pretty well for them for a long time. That's real world experience - not theoretical testing. So it seems to me that we sailors should give a bit more credence to the technique than the JSD website recommends.
Again, I think you're right. Both have merits.
Last edited by smackdaddy : 06-09-2009 at 04:46 PM.
You don't have to be dropped off a wave to have the steering damaged. The force of the wind under the kinds of conditions discussed in this thread, combined with the slacking of the parachute rode because of an out-of-synch moment, are enough to make a boat "hit reverse" with enough speed to damage the steering.
The problem with the JSD is that to be truly effective it should be secured to something equivalent to chain plates on each quarter with metal hardware. I haven't figured this one out yet. After sewing up some 120 GD little cones and feeling like I did time in a sweatshop I am scratching my head trying to work this out without adding hardware that would change the look of the boat.
Guys, despite the large percentage of "conjecture" in this thread, it is good to debate the theory.
The reality, however, might be closer to this:
1) Tank tests are logically of only limited value in determining the applicability of drag devices. Nonetheless, that might be as good as it gets.
2) Real-life oceanic heavy weather, to all reports from those who've survived it, tends toward the chaotic. Few people are going to say "let's take my quarter-million buck yacht out into that whole gale to test the JSD, OK?" The whole point of these devices is that they are more or less worst-case options. It's therefore hard to gauge WHEN and HOW they are best deployed. By when I mean under conditions where it is safe to be mucking about with 120 little parachutes on deck without tearing off your windvane, hooking the backstay or fouling your prop or rudder. Like reefing, it's logical to assume a stern or bow drogue is best deployed some time before conditions merit it.
Whether people DO this is another story...particularly as mentioned, you generally try to avoid such conditions in the first place.
3) Knowing how to deploy these devices might be key to getting them to work properly. In that case, the stern chain plates might be the unacknowledged part of making the JSD work at its best (visuals be damned), just as a bow drogue needs some sort of bridle and block going aft and the proper scrap of sail plus rudder angle to "crab" effectively. They aren't quite "fire and forget" because you have to check for chafe, tangles, shackle deformation and generally be aware of the sea state. On top of that, with the JSD, you are still actively sailing. With hoving to under a sea anchor, you can, proximity to traffic and land permitting, leave the boat to its own (drag) devices.
I think the prudent seaman should have both aboard, and should practice in 25 knots until the bugs are worked out. Old-school sailors used chain, tires, and even anchors added to warps, plus the odd bag of fish oil. In respect that they lived to write how that worked out down, it's clear that anything that slows the boat below hull speed is of a positive benefit in high winds and breaking waves. There is no magic bullet, because there is no one boat and certainly no one sea state that is 100% predictable.
Some old salt in a wooden smack trailing a tire on 300 feet of hawsers in a storm who has done it a dozen times in 30 years is liable to have a higher survival chance than a guy in a Bavaria chucking a JSD off the swim platform for the first time. The merits of the JSD don't even enter into such an equation in this case if the guy with the Bavaria manages, due to a compromised deployment with such a powerfully loaded up drag device, to tear off his stern ladder leaving two fist-sized holes in his boat.
So if you own a drag device, go find 25 knots and eight foot seas and throw it out. Let us know how what works. That way, we'll have a better shot at avoiding tragicomedic results at 50 knots. Advocacy beyond that seems to me to be either theoretical or marketing-driven.
Sorry - I've just got to use this image again. Val, YOU NAILED IT! And you figured out how to use the word "tragicomedic" in a sentence which is freakin' impressive in its own right.
Yes, Don Jordan did recommend having proper chainplates installed to mount the JSD bridle to.
One major point about the experience the Pardeys and many others have had with parachute type sea anchors... these accounts are mostly from older, full keel design boats, and what works for them is not necessarily what is going to work effectively on a more modern fin keel boat design.
The design of the boat is going to be a big determinant of what tactics will work in heavy weather. More modern designs seem to have more problems with lying to a sea anchor than do older, full keel designs did.
__________________
Sailingdog 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.
—Cpt. Mal Reynolds, Serenity (edited)
If you're new to the Sailnet Forums... please read this POST.
You don't have to be dropped off a wave to have the steering damaged. The force of the wind under the kinds of conditions discussed in this thread, combined with the slacking of the parachute rode because of an out-of-synch moment, are enough to make a boat "hit reverse" with enough speed to damage the steering.
The problem with the JSD is that to be truly effective it should be secured to something equivalent to chain plates on each quarter with metal hardware. I haven't figured this one out yet. After sewing up some 120 GD little cones and feeling like I did time in a sweatshop I am scratching my head trying to work this out without adding hardware that would change the look of the boat.
Genie, Joms, Val, etc. - okay, bear with me here. One thing I may not be getting right in all this is the direction of force with breaking waves. How about some pretzel logic?
To try keep this straight - let's have the boat be bow-on for this example...
I understand that when the boat comes onto the face of a wave (as pointed out earlier) it moves in the same direction of that wave. In my mind, this is force 1. And I can totally understand that if the boat is bow-on and gets taken by force 1 strongly enough with a steep enough face, the rudder blows because you do a reverse surf. The direction of the greatest force at that point is from stern to bow because the boat is moving backwards.
We do know that waves can be pretty damn steep and pretty damn high - and as long as they don't break, a boat can ride them relatively safely as long as we avoid the force 1 scenario above. And we know that an anchoring/drogue device deals with this particular force very well. Right?
But here's where it seems to me that things get tricky...
In the event of a breaker atop that wave, you now have force 2 - which is far more powerful than 1. And it's this second force that typically dooms a boat because it's so violent. Correct?
Okay - now if the boat is somewhat stationary because of an anchoring/drogue device and that force 2 hits the boat at 20 knots, with white water smacking into, around, and past it...this particular force is actually moving from bow to stern (because we are essentially held in place bow-to the wave)...right? And this second force is far greater than force 1 - especially if the boat is indeed being held in virtually the same position by the device.
If this is accurate, this is why it seemed to me that the rudder, etc. would suffer less with a breaking wave strike bow-on than it would stern-on because if the device was actually doing it's job keeping the boat in place bow-on to the wave, this huge blast of water would flow past the rudder in the direction it's intended to. If you were stern-to, this blast would actually do what we're trying to avoid with force 1 above, but with far more damaging results because of the greater force of 2.
It seems like when you use any anchor/drogue device that does it's job and you have breakers, you're actually dealing with TWO forces that go in opposite directions. If so, then it comes down to which force is more dangerous. That's the one you have to plan for.
Does this make any sense?
Last edited by smackdaddy : 06-12-2009 at 12:26 PM.
