Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-11-2012, 08:24   #61
Registered User
 
Bluewaters2812's Avatar

Join Date: Sep 2012
Location: Cruising
Boat: Not a Beneteau!
Posts: 911
Images: 1
Send a message via Skype™ to Bluewaters2812
Re: Following Seas Dangers?

Quote:
Originally Posted by Capt.Fred View Post
Someone isn't paying attention
Gee, what's wrong with full sails on a cutter rig or any rig for that matter in a storm; aren't sails designed to take wind lol?
__________________

__________________
Bluewaters2812 is offline   Reply With Quote
Old 13-11-2012, 08:28   #62
Registered User
 
Bluewaters2812's Avatar

Join Date: Sep 2012
Location: Cruising
Boat: Not a Beneteau!
Posts: 911
Images: 1
Send a message via Skype™ to Bluewaters2812
Re: Following Seas Dangers?

Does anyone have actual repeat experience of a particular design of boat as to when (what sorts of speeds too), to deploy the drogue in following seas. I know it is dependent on the following sea conditions, wind etc etc but it would just be interesting to note a few speeds at which deploying the drogue was considered prudent. I am particularly interested in the production type boats like the Beneteau's, Jeanneau's, Hunter's etc but any other actual experience on any design will be welcomed.
__________________

__________________
Bluewaters2812 is offline   Reply With Quote
Old 13-11-2012, 08:39   #63
cat herder, extreme blacksheep
 
zeehag's Avatar

Cruisers Forum Supporter

Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 17,775
Images: 56
Send a message via Yahoo to zeehag Send a message via Skype™ to zeehag
Re: Following Seas Dangers?

i have yet to feel th eneed to use a drogue in any kind of seas, but , then i have never sailed in a hurrycame situation, and i dont plan on starting now.
i have sailed in up to 71 kts of wind, with and without tboomer storms accompanying me.
i prefer to sail these winds and accompanying seas in a ketch . have sailed them in ketch and sloop. sloop was a lot of weather helm and work. ketch is easier by miles. i have sailed decent winds( 20 kts ish ) in a cutter.
most of my way south has been using and encountering lee shores--yes, all west coast is that, and following seas of up to 20-30 ft this trip. if you are nervous of large swells and following seas, do not sail west coast.
the following seas we sailed in gom were babies--only up to 10 ft. until our last run on a prefrontal to st josephs bay--i dont know what sea size was that day--i was busy. had to hand steer, s autohelm 4000 doesnt like seas and winds. had to take pix of dolphins accompanying us--and their babies---
is not the following sea that is the problem, is how the sailor and the boat take such seas.
zeehag is offline   Reply With Quote
Old 13-11-2012, 09:02   #64
Registered User

Join Date: Nov 2009
Location: USA
Boat: Cape Dory
Posts: 439
Re: Following Seas Dangers?

Quote:
Originally Posted by jared View Post
I've read many times and heard many people talk about sailing TOO fast when reaching downwind, even under bare poles. I just assumed they were reffering to the possibility of pitch-poling. However, not many threads here mention that. They do mention Fast Rounding-Up and Broaching.

I've been caught in 2 gales which made for exillerating runs to safe coves downwind. Never did I feel like the bow was gonna dive even with the incredibly steep waves. My problem was the rolling action and how fast the boat would round-up if I wasn't paying attention. The dangerous part in my situation was how fast I needed manauver in close quarters, and leave the helm to get the anchor dropped and set (and do the other 1000 things that need to be coordinated at the same time) before knocking into something. Arrg!

I would like some input as to why those people would say sailing too fast is "dangerous". Is there a dynamic about planing, surfing, and hullspeed that makes it dangerous?

In this scenerio, when they say broaching, do people mean waves are breaking over the stern?
This is an interesting thread. I am learning lots. However, it has drifted a bit from the OP's first question and I haven't heard anyone mention heaving-to or Lin & Larry Pardey. The Pardey's case for heaving to is a rejection of the notion that you can safely run downwind beyond a certain point in heavy weather (so they discuss the causes and timing of broaching in detail). There are 2-3 schools of thought on storm tactics. I suppose, they are somewhat dependent upon your boat (particularly at the extremes - Tahiti style ketch vs modern racing sled) but mostly applicable across the bulk of cruising boats. I would definitely suggest reading the Pardeys (who I think most effectively rebut the cases for the others) also Hal Roth and Allard Coles (the original author of Heavy Weather Sailing -- now much supplemented) maybe throw in some Moitessier for fun.
__________________
Mambo is offline   Reply With Quote
Old 13-11-2012, 09:24   #65
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Following Seas Dangers?

You might also be interested in reading this.
http://www.bethandevans.com/pdf/Downwindsail.pdf

Edit: actually the whole site has a lot of interesting articles.

http://www.bethandevans.com/articles.htm
__________________
DeepFrz is offline   Reply With Quote
Old 13-11-2012, 09:25   #66
Pusher of String
 
foolishsailor's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: On the hard; Trinidad
Boat: Trisbal 42, Aluminum Cutter Rigged Sloop
Posts: 2,314
Images: 19
Quote:
Originally Posted by Ship2210
Does anyone have actual repeat experience of a particular design of boat as to when (what sorts of speeds too), to deploy the drogue in following seas. I know it is dependent on the following sea conditions, wind etc etc but it would just be interesting to note a few speeds at which deploying the drogue was considered prudent. I am particularly interested in the production type boats like the Beneteau's, Jeanneau's, Hunter's etc but any other actual experience on any design will be welcomed.
Here is a great article by none other than our own CFer Maxingout. Tis is one of the best explanations of the core principles of effective weather management strategy. He breaks it to its essential - effective strategy is all about decoupling your boat from the energy in its environment, ie the wind and waves, using technique and/or drag devices...

http://positivegraphics.com/Blue_Water_Catamaran.htm

And here is a link to one of the better reads on the whys and how's of utilising drag devices. Some serious sailors were contributing to this thread it's a good read.

Series Drogues & Heaving To
__________________
"So, rather than appear foolish afterward, I renounce seeming clever now."
William of Baskerville

"You will do foolish things, but do them with enthusiasm."
Sidonie Gabrielle Colette
foolishsailor is offline   Reply With Quote
Old 13-11-2012, 10:54   #67
Registered User
 
Bluewaters2812's Avatar

Join Date: Sep 2012
Location: Cruising
Boat: Not a Beneteau!
Posts: 911
Images: 1
Send a message via Skype™ to Bluewaters2812
Re: Following Seas Dangers?

Quote:
Originally Posted by foolishsailor View Post
Here is a great article by none other than our own CFer Maxingout. Tis is one of the best explanations of the core principles of effective weather management strategy. He breaks it to its essential - effective strategy is all about decoupling your boat from the energy in its environment, ie the wind and waves, using technique and/or drag devices...

Blue Water Catamaran - Exit Only Sails Offshore Around The World.* Captain Dave - Privilege 39

And here is a link to one of the better reads on the whys and how's of utilising drag devices. Some serious sailors were contributing to this thread it's a good read.

Series Drogues & Heaving To
Thanks for those links. I had a look at them and keep adding to my personal knowledge base as a result.
__________________
Bluewaters2812 is offline   Reply With Quote
Old 13-11-2012, 12:40   #68
Registered User

Join Date: Feb 2012
Posts: 2,441
Re: Following Seas Dangers?

Regarding the "Blue Water Catamaran" article:

I have no argument with the methods (and, having no offshore multihull experience, no basis to argue from) but I am uneasy about the rationalisation, specifically the concept of 'decoupling your boat from the energy in its environment'

Here's my take on the statics and dynamics:

A wavetrain is a way of moving energy through a stationary body of water.

What a drogue does is to couple the boat positionally to a collection of water particles.*

However (neglecting currents) the water is essentially going nowhere, so it does NOT travel in the direction of energy transport.

By coupling the boat to the stationary body with a drag device, you're creating a potential difference between the zero kinetic energy of the boat and the considerable kinetic energy of the wavefonts, particularly the crests.

Just as when you "earth" yourself, you create a potential difference between yourself and an electrical conductor.

It's not helpful to say that in doing so, you're "decoupling" yourself from the energy in that conductor: you're actually exposing yourself to energy transfer, by coupling yourself to a different energy level.

If the electrical analogy doesn't work for you, here's a different one: A wave crest which collapses forwards runs down the wavefront a bit like a powder avalanche. Imagine being swept down the mountain.

Alternatively imagine yourself "earthed", in other words, harnessed to a ringbolt further up the mountain by a rope. It might be a good thing depending on the alternatives, but it's not decoupling yourself from the energy in your environment, in any meaningful way.

A sea anchor ideally behaves like a seafloor anchor with a soft snubber. If that's the effect you want, all to the good, but again, you're not decoupling the boat from the energy in the environment.



It seems to me such a tactic implies that you've decided it's the lesser of two evils to risk the 'potential difference' effect mentioned above, in exchange for holding the boat in an attitude (ie end-on) which will be minimise the energy transfer across that increased potential difference.

It seems to me this is a particularly viable choice in a situation where you can't be sure of avoiding going side-on at speed, particularly in a boat with very high form stability (like a multihull, or very beamy mono)

Alternatively a drag device could be a strategy to hold the boat from being carried downwind towards a stationary danger, (like a cliff, in the mountain analogy)

or it might have a foot in both camps.


* In high waves, water particles travel alternately upwind and downwind due to the underlying orbital motions in wavetrains.
A series drogue does a better job than a single-element drogue of averaging different phases of the various orbits over a longer sample, so it is not critical to have the drogue at the right distance from the yacht.

This avoids the risk of being towed towards a breaking crest because you're coupled to an unfavourable orbit, some distance away.
__________________
Andrew Troup is offline   Reply With Quote
Old 13-11-2012, 14:42   #69
Pusher of String
 
foolishsailor's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: On the hard; Trinidad
Boat: Trisbal 42, Aluminum Cutter Rigged Sloop
Posts: 2,314
Images: 19
I appreciate your dissection as usual Andrew, however lets make sure we are using the same values for some critical variables in this discussion.

You bring up a valid point about the idea that a drag device does not "de-couple" one from the energy transfer but instead anchors you to a lower energy state. In fact this statement you made is fantastic as I didn't think of it in these terms. However it makes me think of the idea that while we may be talking about to energy states like two different states an electron can be on in an atom the difference thoguh with a sailboat is that the energy transfer between these two states is diffused.

If you choose a device like a parachute anchor you do create a dramatic difference between the energy state of the wave energy and the static water as the parachute anchor holds you for all intents and purposes dead in the water, however the full energy of the waves is not transferred onto the hull by design. Only X number of square inches receives the full blow, the part of the bow effectively perpindicular to the wave force. The shape of the hull diverts the vast majority around the boat.

If you chosose a device like a drogue, there is a smaller difference in energy states as the drogue is designed to keep you making way, however the trade off is that you present more square feet of boat to the full force of the energy discrepancy.

If you choose a series drogue, my preference for the current boat I own, you present even less discrepancy as the boat is moving at up to four or five knots if using a variable length and speed drogue.

Other techniques present other issues and benefits.

However the main point is that you are in control. You are actively making the choice to engage in this versus the dangerous result of the weather choosing it for you. As he explains imagine the result of nature choosing to decouple you from the wave train. The only way she does that is a broach or pitch pole in the trough where the boat suddenly goes form at least hull speed to zero instantly.
__________________
"So, rather than appear foolish afterward, I renounce seeming clever now."
William of Baskerville

"You will do foolish things, but do them with enthusiasm."
Sidonie Gabrielle Colette
foolishsailor is offline   Reply With Quote
Old 13-11-2012, 17:52   #70
Capt. Fred
 
Capt.Fred's Avatar

Cruisers Forum Supporter

Join Date: Nov 2009
Location: Gulf Coast Alabama
Boat: Blackwatch 19 gaff rig cat
Posts: 156
Images: 5
Re: Following Seas Dangers?

I'm so pleased to be one of the last on this thread.
Does anyone think or know if there is a correlation of between the spacing of the waves and the distance the drogue should be set out from your bow? I suppose wave speed, wind speed and wave height are factors, but what is good judgment in all your collective opinion?
__________________
Capt.Fred is offline   Reply With Quote
Old 13-11-2012, 19:17   #71
Registered User

Join Date: Feb 2012
Posts: 2,441
Re: Following Seas Dangers?

Quote:
Originally Posted by foolishsailor View Post
... while we may be talking about to energy states like two different states an electron can be on in an atom the difference thoguh with a sailboat is that the energy transfer between these two states is diffused.

.....
I like your analysis, FS (can't bring myself to use your full 'forum handle', wouldn't quite seem respectful, summow!)

I didn't deal with the intermediate values of the 'coupling' variable, as you point out.

I didn't explore the range of intermediate options, because what I was trying to do was to reduce the potential for confusion. What was being recommended in the linked article, and labelled as decoupling, looked (to me) very much more like coupling.

Because of that, I got the feeling, reading the detailed rationale, that I sometimes get when reading a non-technical journalist's explanation of a technical topic. Sometimes they're concentrating on taking notes rather than concentrating on how the explanation fits together, and end up reporting a key concept exactly backwards.

Particularly frustrating if you're the person whose thoughts they are reporting! In their defence, the target readership generally don't notice....

In practice, perfect coupling to the relative immobility of the watermass is neither possible nor (unless very close to a lee danger) desirable, but I was looking at a simplified abstraction, with "coupling" values of either zero or one.

It seemed to me that the advertised benefits were actually not so much about energy coupling or uncoupling, but more about dynamic stability. What was being advocated was intended to reduce potential control problems, and adverse consequences, arising from overspeed.

In doing so, control is maintained over orientation to present the vessel end-on, as your post explains and mine briefly mentioned. This provides one partial antidote to the risks of coupling the vessel to the immobile watermass.

Reducing the degree of coupling, allowing the boat to maintain steerage way (which you talk about, using drogues rather than, say, a parachute) is another (partial antidote).


It's a fair observation that I was concentrating on different values of this critical variable than you, and different than reality, which was confusing given that I did make mention of series drogues and such.

Incidentally I'm surprised you'd expect to be so "uncoupled" as to be doing something approaching five knots with a series drogue which seems to me would surely represent either a phenomenal windspeed, implying massive loadings ... or a rather minimalist drogue, offering barely more drag than a warp?

I personally quite fancy the idea of something along the lines of a Seabrake which was a sort of towable rocket nose-cone, with a simple adjustable spring mechanism. Above a certain speed through the water it would open petal-like scoops progressively. I recall Peter Blake was a fan of these, but I've never seen one used in anger.

Another idea I've toyed with but not yet tried would be a 'light drag' device passing through a full-house fairlead on the centreline of a strong bumkin aft of the hull, to provide a decent lever arm.

(Fairleads can be a problem with drogues on modern hulls in several ways)

Ideally the drogue exiting the fairlead would, if it went offcentre, deflect a lever which would apply rudder via the self-steering mechanism to more quickly and powerfully bring the boat back in line with the drogue, and by implication, the seaway, at the first hint of an impending broach

... while the swinish crew snored mindlessly belowdecks....

It's a concept the better servo pendulum vanes try to exploit, but I think this implementation could potentially provide a signal which was stronger, cleaner and more authentic in survival conditions.


Seems to me that either or both of these would support a "partially coupled" state: relatively high speed, low drag drogue, which feels to me like a more lightweight, agile approach to the problems.

My over-riding preference, given the ideal situation of a new build, is to concentrate on aspects of boat design which minimise both the likelihood, and the consequences of a broach in such conditions.

Mainly I see merit in a boat which can look after itself in most conditions, without being pinned down in the way a drag device implies.

To me, such design attributes include: (and I'm not pretending all these need to be present, let alone optimised, in every offshore boat - it's just my personal bucket list):

U-shaped forebody sections to provide lift and minimise 'bow steering', chain locker back amidships, (with perhaps an inshore-only locker at the bow), relatively narrow waterline beam, flared topsides, low freeboard, low deckhouse or flush deck, especially aft; moderate displacement and shallow draft, modest standing rig height, reasonably balanced underwater shape to the maximum extent consistent with moderately powerful quarters, large, deep and strong tandem rudders carried well aft, and a swing keel designed to move the CLR way aft when mostly retracted (or a tandem lift keel arrangement)

Many of these items require serious compromises, but I'm currently working on a design which resolves these in ways I'm personally pretty happy with.
__________________
Andrew Troup is offline   Reply With Quote
Old 14-11-2012, 03:19   #72
Pusher of String
 
foolishsailor's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: On the hard; Trinidad
Boat: Trisbal 42, Aluminum Cutter Rigged Sloop
Posts: 2,314
Images: 19
Re: Following Seas Dangers?

Quote:
Because of that, I got the feeling, reading the detailed rationale, that I sometimes get when reading a non-technical journalist's explanation of a technical topic.
This is the crux of it really. I think the article has to be seen as a layman to layman discussion versus a truly technical one.

Quote:

It seemed to me that the advertised benefits were actually not so much about energy coupling or uncoupling, but more about dynamic stability. What was being advocated was intended to reduce potential control problems, and adverse consequences, arising from overspeed.

I think this is fair. It is designed more to help conceptually deal with the topic than to describe the actuall physics, other than the hard fact that inertia is the killer and reducing that variable is what keeps boats and crews safe in dangerous conditions.



Quote:
Incidentally – I'm surprised you'd expect to be so "uncoupled" as to be doing something approaching five knots with a series drogue – which seems to me would surely represent either a phenomenal windspeed, implying massive loadings ... or a rather minimalist drogue, offering barely more drag than a warp?
I use a home built jordan series drogue and find my actual speed to be around 2kts, however i have read and heard that some carry an additional "lighter" series drogue with fewer cones and also, it might have been Starzinger talking cant remember, a drogue of variable length. However I cant see how it would be made as drogues run off a bridle and i cant imagine a reliable non-complex system that would allow one to shorten or lengthen the part of the line that is loaded up with cones...



Quote:
Another idea I've toyed with but not yet tried would be a 'light drag' device passing through a full-house fairlead on the centreline of a strong bumkin aft of the hull, to provide a decent lever arm.

(Fairleads can be a problem with drogues on modern hulls in several ways)
See above. Re: Fairleads - yea considering the loads and potential shock loads involved in these devices this would be a difficult arrangement to make bulletproof


Bottom line for me is that the drag device has a couple of benefits besides just keeping a boat from broaching in the trough or broaching due to whitewater over taking the stern. It also


1. radically smoothes out the motion of the boat
2. since you have made the decision to run before the storm with a drag device off your stern, the device slows the boat dramatically and the period of the bad weather passes over more quickly than if you ran before making 8 or so knts.


I have never carried or used a parachute anchor - only used a galerider, warps or a series drogue.


Quote:
U-shaped forebody sections to provide lift and minimise 'bow steering', chain locker back amidships
If you can afford to design/build your own boat the specs you mention, especially these, would make for an intersting boat.

edit:

Quote:
and a swing keel designed to move the CLR way aft when mostly retracted (or a tandem lift keel arrangement)
I have this exact setup on my boat. I lift the forward keel approx 75% which shifts the CLR aft and I have a trim keel 1m infront of my rudder that I drop. it is 25% the size of the main keel. It acts like the fletching on an arrow and makes for an incredibly fast downwind ride that is easy on the autopilot in moderate conditions and a much smoother and safer ride in heavy conditions.
__________________
"So, rather than appear foolish afterward, I renounce seeming clever now."
William of Baskerville

"You will do foolish things, but do them with enthusiasm."
Sidonie Gabrielle Colette
foolishsailor is offline   Reply With Quote
Old 14-11-2012, 04:02   #73
Pusher of String
 
foolishsailor's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: On the hard; Trinidad
Boat: Trisbal 42, Aluminum Cutter Rigged Sloop
Posts: 2,314
Images: 19
Re: Following Seas Dangers?

Quote:
Originally Posted by Capt.Fred View Post
I'm so pleased to be one of the last on this thread.
Does anyone think or know if there is a correlation of between the spacing of the waves and the distance the drogue should be set out from your bow? I suppose wave speed, wind speed and wave height are factors, but what is good judgment in all your collective opinion?…
Parachute anchor is designed to stop the boat as close to dead in the water as possible. It is streamed from the bow. You dont want a drogue streamed from the bow as it is designed to allow the boat to move through the water and if you are moving backward on a wave face you are likely to snap your rudder. There is however an instance of a boat using a drogue off the bow but it was a creative application used in conjunction with heaving to. Here is the link:

Galerider Drogue Launched Off Bow Stops Wave Strikes While Heaved-to

In terms of the distance a drogue should be streamed off the stern it is directly related to wave period. You want the device in the trough when you are one the crest so that it doesnt pull out and skip allwoing you to accelerate when you really dont wish to. Ideally 1.5 times the Wavelength of the waves you are in.

You can calculate the distance between peaks using the following formula...

L = Wavelength (distance between peaks)
T = Period (time between peaks)
C = Speed of waves

T is easy just time from one peak to the next, you can do it day or night.
C is approx 1.56*T in deep water

Then you pplug into this forumla to get distance between peaks

L = C*T

However since most of us are in no mood to be doing math calculations and estimates in the conditions that we are usualy considering the use of a drag device you can also just estimate that the length of the rode should be by your feel for the height of the waves.

A 10m wave generally has approximately 100-150m wavelength
15m wave has aproximately 200-250m wavelength
__________________
"So, rather than appear foolish afterward, I renounce seeming clever now."
William of Baskerville

"You will do foolish things, but do them with enthusiasm."
Sidonie Gabrielle Colette
foolishsailor is offline   Reply With Quote
Old 14-11-2012, 13:08   #74
Registered User

Join Date: Feb 2012
Posts: 2,441
Re: Following Seas Dangers?

Quote:
Originally Posted by foolishsailor View Post
....

I use a home built jordan series drogue and find my actual speed to be around 2kts, however i have read and heard that some carry an additional "lighter" series drogue with fewer cones and also, it might have been Starzinger talking cant remember, a drogue of variable length. However I cant see how it would be made as drogues run off a bridle and i cant imagine a reliable non-complex system that would allow one to shorten or lengthen the part of the line that is loaded up with cones... ....
.
If you're happy to run at five knots, I'm not convinced you would actually need cones. A hairy old manila warp of sufficient length could well be sufficient, which would alleviate handling problems.

Quote:
Originally Posted by foolishsailor View Post
....
Re: Fairleads - yea considering the loads and potential shock loads involved in these devices this would be a difficult arrangement to make bulletproof

.
I guess I see one of the benefits of a light-handed drag device to be reduced load on cleats and fairleads.

A bumkin could conceivably provide sufficient "gain" or amplification of the signal that a relatively light drag would suffice to prevent broaching, even without the notion of a linkage to the steering which I floated, but I recognise the other benefits you perceive from heavier drag, and I'll comment to these below.

Light drag implies lower loads on the fairlead -- which in any case, are almost non-existent fore and aft, which is the ruling direction for both steady loads and shock loads.

If the drag is serving its purpose, loads will also be minimal laterally, as they are proportional to the deflection angle. However they could be significant downwards.

{Part of the reason I'm exploring the bumkin idea in relation to the boat I'm designing is that the ability to move the CLR radically far aft, while clearly beneficial to the inherent dynamic stability, reduces the lever arm of the drogue relative to the new pivot position. I don't plan to build it, just design the stern structure to allow retrofitting it later, if the boat does not prove as broach-immune as I hope.

I see another benefit as being keeping the drogue well aft during retrieval.

Often the worst seas are encountered during the waning phase of windstrength and it's important to get underway sooner rather than later. This can present retrieval difficulties. I visualise it might be necessary to provide an alternative source of retardation to the boat by running the propellor in reverse.
However this is a scary proposition in another respect: it would be a big advantage to have the fairlead well clear aft of the boat, so you had good sightlines from the retrieval winch, and could hit neutral the moment you saw the drogue at risk of being carried forward under the hull by a following sea}

Quote:
Originally Posted by foolishsailor View Post
....
... the drag device has a couple of benefits besides just keeping a boat from broaching ...
It also
1. radically smoothes out the motion of the boat

.
Are you sure about this? The only smooth rides I've ever had in storm force winds have been running at speed. Admittedly usually (but not always) in a well-mannered hull with a relatively modern forebody and underbody ....

but even on a heavy old high-deadrise, slack garboards tub like Joshua, Moitessier reported the same thing when he took an axe to the warps he was towing, in the survival storm of his sailing career.

I would have thought that the reduced frequency of encounters with wave crests would support in theory what I've observed in practice.

Still, I recognise that these are complex, organic situations, each of which is markedly different from all others, so what I have observed is not a reliable guide to what I or others will encounter in the future (one of the benefits of sharing ideas widely, no?)

Would love to hear more of your thoughts on these questions if you find the time.

Quote:
Originally Posted by foolishsailor View Post
....
2. since you have made the decision to run before the storm with a drag device off your stern, the device slows the boat dramatically and the period of the bad weather passes over more quickly than if you ran before making 8 or so knts.

.
Agreed ... but I would point out that you still get passed by the same number of waves during that shorter period...

Particularly if the waves are close together, I prefer to stay on each one as long as possible, because it often takes time for the boat's wobbles to settle after tipping off the back of each crest, and it's nice to allow time for her to 'assume a Tai Chi position' in time for the next assault....

If the waves are far apart, say in the Southern Ocean, it's often the case that you can sidle slightly sideways out of the worst of it, if you're already to one side of the deepest gradient (which statistically you are quite likely to be) by going onto the appropriate (notional) gybe and reaching up a bit during the long intervals between crests. Even with no sail this is likely to be doable. Of course this relies on having some speed, and it's perhaps this sort of tactic where something like a SeaBrake might be invaluable, providing drag only during isolated instances of overspeed.

--------------


(pertaining to aftwardly movable effective keel planform):


Quote:
Originally Posted by foolishsailor View Post
....
edit: I have this exact setup on my boat. I lift the forward keel approx 75% which shifts the CLR aft and I have a trim keel 1m infront of my rudder that I drop. it is 25% the size of the main keel. It acts like the fletching on an arrow and makes for an incredibly fast downwind ride that is easy on the autopilot in moderate conditions and a much smoother and safer ride in heavy conditions.
Yay !

I should explain that my earliest influence in these matters was from the French school, initially 'Damien II' which I did some engineering work on in the 1980s, and a family member crewed to Antarctica, but then we struck up a friendship and did some sailing with the skipper of 'Fixin', which was an early Trismus, built in alu with the system you describe, and fitted out by the skipper (who was one of the most resourceful people I have ever met).

Fixin almost sank, running before a storm out of Cook Strait, due to a Lego block, and then was nearly lost on a bar twenty miles from where I'm writing this, but those are stories for another day ....
__________________
Andrew Troup is offline   Reply With Quote
Old 15-11-2012, 03:13   #75
Registered User
 
Bluewaters2812's Avatar

Join Date: Sep 2012
Location: Cruising
Boat: Not a Beneteau!
Posts: 911
Images: 1
Send a message via Skype™ to Bluewaters2812
Re: Following Seas Dangers?

No offence intended but I find myself skipping past the long, technical posts on this thread and searching for shorter, practical, experience-based posts. Not saying the long technical posts should stop, as I am sure there are those that are interested in them; just hoping for a few more shorter, practical post will pop in.
__________________

__________________
Bluewaters2812 is offline   Reply With Quote
Reply

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




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:21.


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.