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Desirable and Undesirable Characteristics of Offshore Yachts


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1 minute ago, Fah Kiew Tu said:

So - you aspire to reach the dizzy heights of competence as practiced by Rimas, then?

FKT

 

Oh shit, yer killin' me. I just got back from a Blues Society BBQ/jam session, kinda liquored up, fingers sore, and I see this. 

I needed a laugh, thanks!

 

 

 

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That in no way diminishes the validity of their choices. They are buying the boat for themselves, not for you or me. I happen to prefer a deep fin, spade rudder, tall carbon rig, paradoxically on a wo

This has turned into Desirable and Undesirable Characteristics of Offshore Posters.

You know who to get the best advice from? Delivery skippers. It isn't their boat, they aren't in love with her and blind to her flaws. They have to get the boat from A to B despite the weather or

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25 minutes ago, Fah Kiew Tu said:

So - you aspire to reach the dizzy heights of competence as practiced by Rimas, then?

FKT

One of the coolest books about non-instrument navigation...written in the ‘50s by a famous Aussie dude who flew around the world in the 1930s...https://www.amazon.com/Finding-Your-Way-Without-Compass/dp/048640613X/ref=mp_s_a_1_4?dchild=1&keywords=natural+navigation&qid=1620961717&sr=8-4 who also wrote a classic book called “The Raft Book”, on ocean nav without instruments...perhaps the modern version of which is the book “The Barefoot Navigator”,’ also quite good - looks at how other cultures have solved the navigation problem (Vikings, Polynesians, etc).

https://www.amazon.com/Barefoot-Navigator-Wayfinding-Skills-Ancients/dp/1472944771/ref=mp_s_a_1_2?dchild=1&keywords=barefoot+navigator&qid=1620961121&sr=8-2

Rimas had available to him centuries of humanity’s greatest navigational lore, tradition, and knowledge...endless fascinating wisdom to draw on...yet the fool in him is strong :-)

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1 minute ago, Jud - s/v Sputnik said:

One of the coolest books about non-instrument navigation...written in the ‘50s by a famous Aussie dude who flew around the world in the 1930s...https://www.amazon.com/Finding-Your-Way-Without-Compass/dp/048640613X/ref=mp_s_a_1_4?dchild=1&keywords=natural+navigation&qid=1620961717&sr=8-4 who also wrote a classic book called “The Raft Book”, on ocean nav without instruments...perhaps the modern version of which is the book “The Barefoot Navigator”,’ also quite good - looks at how other cultures have solved the navigation problem (Vikings, Polynesians, etc).

https://www.amazon.com/Barefoot-Navigator-Wayfinding-Skills-Ancients/dp/1472944771/ref=mp_s_a_1_2?dchild=1&keywords=barefoot+navigator&qid=1620961121&sr=8-2

Rimas had centuries of humanity’s greatest navigational lore, tradition, and knowledge...endless fascinating wisdom to draw on...yet the fool in him is strong :-)

If you haven't got it, David Lewis' book 'We the Navigators' is worth a read too.

Myself, I'll stick with redundant numbers of GPS and hope the different satellite setups don't all fail at once. I own a sextant and once was able to use it for more than cross angles but those days are long in the past and I'm in no mind to revisit them.

FKT

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1 hour ago, Fleetwood said:

But I expect you could if severely motivated.

Well enough to find a place as big as Australia, sure. A low lying atoll, perhaps only via Braille navigation.

FKT

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2 hours ago, Fah Kiew Tu said:

Well enough to find a place as big as Australia, sure. A low lying atoll, perhaps only via Braille navigation.

FKT

Hard to miss the mainland, Tassie another matter..........

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14 hours ago, Fah Kiew Tu said:

What, like manual anchor winches for example?

I'm just swapping mine out for an electric one...

FKT

No, we're not Luddites.  Like you I'm the deck monkey and she drives.  We've got most of the goodies: electric windlass, B&G instruments, refrigeration, solar, LED lights, radar....etc..  But steering, navigation, lighting, plumbing and cooking are ether manual or have a manual backup.  To my parents, who grew up sailing in the 50's and 60's, and took us cruising as kids, the gear is all standard stuff.  

Some stuff like the windvane and leadline we use all the time. Some stuff like the sextant mostly gets used for fun because we would have to break or lose power on somewhere near six GPSs if you include all the iDevices.  Some stuff, like the walker log & speedo or LPG solenoid bypass sit in a box 99% of the time and I debate the space they take up.  The oil lamps provide nice atmosphere and take just enough of the chill off the cabin in a Maine Summer.  

When we started refitting our boat, we had to go through 2-3 seasons where the newly rebuilt engine was very unreliable (big famous yard, '"reputable" engine shop, lots of $$$), so we learned to do without motive power and husband our voltage.  It was my wife's first time on a sailboat, so she thinks that's just how it is. :D 

Come to think of it, the one time I really did let the magic smoke out of my electrical system was due to the windlass.  PO sabotage I say...but it's my fault for not figuring out what he did. 

This year we're getting a Vesper AIS transponder with wifi - so we're finally entering the 21st century. 

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26 minutes ago, Elegua said:

 The oil lamps provide nice atmosphere and take just enough of the chill off the cabin in a Maine Summer.  

I really like oil lamps.  Look good - nice light, easy to maintain and as you say put off a nice amount of heat.  We had a big hurricane lamp and it was our 'regular cabin heater' we only fired up the drip diesel heater if it was seriously cold.

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21 hours ago, Jud - s/v Sputnik said:

Here’s a dead simple example.

I was in downtown Vancouver, a semi-large North American city.  A family approaches, tourists, clutching a phone with Google maps or similar open.  They’re looking for directions to a rather rough nearby street, and can’t seem to locate it but despite having what is effectively a powerful computer with a GPS-enabled map on it...and in a city with grid-pattern streets...yikes!

The description of this book below has it all wrong - “what does it mean to never get lost” - a book that describes itself as “examin[ing] the rise of our technologically aided era of navigational omniscience-or how we came to know exactly where we are at all times.”

Many know where they are, but are actually, in fact, lost (because they’ve lost sight of the larger context, like that famous Dutch Volvo Ocean Race boat near the Seychelles).

687FAF7F-AB24-4210-970D-C90D4CB3A292.jpeg

There was a study a few years back of twenty somethings and their inability to locate themselves on a globe. One of them was a geography major in college! I suppose it would only be fair to repeat the study with boomers. Might not do much better. 

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So, in or first years of boat ownership it was pretty much D/R which, in SoCal is hardly a challenge. Our first trip was to China Cove on San Clemente Island, followed by the back side of Catalina and then home. Rounding Castle Rock on the north side of San Clemente, I set a course for Cat Harbor and turned the helm over to my wife, the native San Diegan, and went below for a nap. About an hour later she called me up topside in a panic: “We missed Catalina and we’re heading back to California”. Peering through the haze I see the unmistakable outline of Catalina and told her we were on course. Boy was she disappointed that it looked just like the mainland. She was expecting a tropical paradise. 
 

“No, Honey, we would have to sail south for several weeks“. (She’d kill me for telling this story if our ID were outed.)

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On 5/13/2021 at 7:18 PM, Fah Kiew Tu said:

Exactly. I'm sick of cranking in the chain while my GF handles the wheel & engine controls. As she's 152cm tall and weighs 57kg she's not about to swap positions.

My boat has a moderately complex wiring/electronics system but as I used to look after much much more complex systems, and I installed everything myself, I can either fix it or work around it. Lot of redundancy. The basics are very strongly constructed including the steering gear.

FKT

My advice is, whatever size windlass you think you need, go up one size. Of course, that's the same advice I give on anchors and the rest of a ground tackle system.

If you are doing serious cruising, there may be a time when that oversized ground tackle will be what gets you through a very difficult time. It may be the difference between a disaster and a night of lost sleep.

The Lofrans Falkon windlass we put on our heavy 40' cutter was the same one they put on the Fleming 55 motoryacht.  So was the 60 pound CQR, and the 400' of 3/8" G4 chain.

Good ground tackle is what keeps you secured in place on planet earth when you are surrounded by hard, nasty stuff that wants to eat your boat.

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2 hours ago, accnick said:

My advice is, whatever size windlass you think you need, go up one size. Of course, that's the same advice I give on anchors and the rest of a ground tackle system.

I installed a Muir HR1600 winch. Plan is for its own battery and a VSR to keep the fwd battery charged.

The winch is now on deck and cable holes cut through the steel floors which was the expected shit of a job. I cursed the builder for his bloody-minded insistence that more holes weren't necessary I can tell you. Anyway the paint is on so running cable is next. The control box is wired & tested.

I'm sure it will all go swimmingly well along with all the other upgrades including replacing the Vesconite stern bushing I just broke (good thing I made a spare when I made the one fitted). In fact I may start a new thread - fettling for fun and profit.

FKT

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On 4/29/2021 at 3:00 AM, estarzinger said:

I am curious - for 'serious' offshore work, like a shoulder season N atlantic crossing - how do you feel about pogo stability?  It is obviously just fine for even heavy duty coastal (several nights) sailing . . . . 

 

edit: I'm also curious - running in big breaking waves - keel down or up?

Keel down, always keep the keel down! On some boats with these lifting keel, you might want to lift the keel 10% to enhance directional stability but I doubt that the Pogo is one of them.

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4 hours ago, Panoramix said:

Keel down, always keep the keel down! On some boats with these lifting keel, you might want to lift the keel 10% to enhance directional stability but I doubt that the Pogo is one of them.

hmmm . . . You do realize the flat bottom centerboard boats down in the south pretty much all go keel up for those sorts of conditions (some with additional rear dagger boards down)?

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i would think the ability to slide and not trip over the draft might be of some advantage, tempered by the desire for maximum moment. 

I thought it was interesting in tank testing when they pulled masts out of models and they were much easier to roll in simulated breaking seas.

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23 minutes ago, Cruisin Loser said:

i would think the ability to slide and not trip over the draft might be of some advantage, tempered by the desire for maximum moment. 

I thought it was interesting in tank testing when they pulled masts out of models and they were much easier to roll in simulated breaking seas.

yes.

 Our first RTW was on a centerboard boat - but it was a different design (CCA, stub keel, only lightly ballasted board).  We ran board up.  

The boats in the south accumulate quite a bit of empirical experience with difficult conditions.  The ones I knew well, ran keel (heavily ballasted boards) up, and I think they had been knocked to 70-90 but none further than that.  They ran like arrows, easy on the helm in the most difficult situations.

But there are aspects I'm sure I dont understand - why I asked the question. I suspect it is rather more complicated than those focused on AVS/righting moment appreciate. I'm not sure how much experience we have on here with these sorts of boats in breaking wave conditions (those conditions are relatively rare).

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1 hour ago, estarzinger said:

hmmm . . . You do realize the flat bottom centerboard boats down in the south pretty much all go keel up for those sorts of conditions (some with additional rear dagger boards down)?

Yes but centreboard boat have most of their ballast in the boat or in the keel stub. Proper lifting keels boats rely on the lifting keel for their stability so if you want to stay alive you definitely keep it down except may be the first 10% of draft as it enhances directional stability by bringing the centre of lateral resistance aft. If you don't keep it down, first time you broach violently or get hit by a bad wave you risk ending up on your side. Anyway on these boats in bad weather you absolutely want to keep some speed ( I would say minimum 5 knots downwind, 3 or 4 upwind) and if the boat starts to speed up (wind or wave) it will go in a straight line, so lack of directional stability is not a real issue.

TBH, even if they haven't been designed to sail "down in the South", a Pogo will be safer than most production boats as for a start they are actually watertight unlike most production boats and very well engineered as they are designed to be pushed very hard.

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1 hour ago, Panoramix said:

 Proper lifting keels boats rely on the lifting keel for their stability

The boats I am referring to in the South Do in fact have very heavily ballasted (lead) boards. I'm sure the board would effect the avs a ton.  But they still go board up.

first time you broach violently

And a (big) reason is that with the board up - they DONT 'Broach violently'.

you risk ending up on your side.

There is a risk of 'knock over' (eg 70-90 degrees) with almost all designs (in breaking waves). And you build your boat for the south just assuming you are going to get knocked over every couple years (at the very least least).  Empirically it seems (with a high degree of variability and noise) that the boats with board up may get knocked over more frequently but get knocked down (>90 degrees) less often than deep keel boats. 

I would say  . . . . minimum 5 knots downwind

My personally experience is that depends a whole lot on the boat design.  Some I have sailed liked 6kts, and others liked 2kts. Out of curiosity - have you ever actually run in true storm (sustained winds*, NOT just gusts, >48kts) conditions, with actual breaking waves (not just breaking crests)?

 a Pogo will be safer than most production boats

Sure. However, note - that is not a very high benchmark. Most 'production boats' are in fact not built that well. also note I am not, and have not knocked pogo's here at all. We have some good (French in fact) friends who had a custom but very 'pogo' design - very nice boat. We first met them in the south but they only spend one season there and did not do the harsher bits - not because of the boat, but because they simply did not want to - Horn was they sole objective down there and then they preferred to get to warmer weather.

* note: there is some standards variability around the world on what averaging period should be used for sustained winds - I have seen definitions between 1 minute to 10 minutes. We set our B&G to 2 minute (for various reasons).  But even 1 minute is way way different result than the normal 'gust' settings.

 

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1 hour ago, Panoramix said:

.......

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

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At the end of the day you sail what you have and if you don't like it you move onto something else.  Just finished a light air passage back to the East Coast, mostly sailing but a bit of motoring too, lotsa dead down wind.  Didn't bother with the kites, to lazy.  We did catch 2 Albacore and ate 30 six packs of Oreo's.  Now off to Portland.

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1 hour ago, estarzinger said:

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

It's the Sailor's Categorical Imperative: "There is only one correct way to do things and that is my stated way* of doing things and if you do things differently you are an idiot and will die."

*NB: "I may not obey these absolutist rules myself, but I am steadfast in pushing my beliefs on others."

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

You get it a bunch in woodworking as well, and I suspect car/motorcycle/aircraft circles.

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The dynamics of breaking waves calls into question the notion of "tripping" on the keel. I think the Southhampton studies illuminated this. Simplistically, the boat is turned over by a water surface that remains still and parallel to the waterline in the boat's frame of reference. Tripping while broaching has different dynamics.

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1 minute ago, DDW said:

 "tripping" on the keel.

I am by no means deeply knowledgeable about the physics of this . . . but my sense has been that it has more to do with steering balance than actual 'tripping'. That is the deep keels are generally designed to provide efficient lift to windward, and when running and you get heeled on a wave they 'encourage' you into a broach, which puts you beam on to a wave which then rolls you.

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Just now, DDW said:

The dynamics of breaking waves calls into question the notion of "tripping" on the keel. I think the Southhampton studies illuminated this. Simplistically, the boat is turned over by a water surface that remains still and parallel to the waterline in the boat's frame of reference. Tripping while broaching has different dynamics.

Yeah -- when the boat is lifted bodily up and falls vertically onto its side, the finer points of yaw characteristics rather fall by the way. (Tho you could say a boat with optimal broach resistance is less likely to find itself beam to a breaking wave, so the hydrodynamics are still worth considering.)

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I have an urge to whittle a hand full of hull shapes (with correct weight distribution and spar weights), take to the beach and see what happens.  

Steve

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13 minutes ago, Panope said:

I have an urge to whittle a hand full of hull shapes (with correct weight distribution and spar weights), take to the beach and see what happens.  

Steve

That's Zonker's job, Steve. Yours is to test anchors. Stay in your lane.

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1 minute ago, IStream said:

That's Zonker's job, Steve. Yours is to test anchors. Stay in your lane.

Zonker DESIGNS the shapes.  I whittle and test (and film, of course).

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1 minute ago, Panope said:

Zonker DESIGNS the shapes.  I whittle and test (and film, of course).

Okay, just make sure you attach little anchors to them and I think you'll get by on a technicality.

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9 minutes ago, IStream said:

Okay, just make sure you attach little anchors to them and I think you'll get by on a technicality.

I like that Idea.  

A recreation of the '82 Cabo disaster.

If I remember correctly, most of boats that did not drag ashore were using CQR and Bruce.

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52 minutes ago, Diarmuid said:

Yeah -- when the boat is lifted bodily up and falls vertically onto its side, the finer points of yaw characteristics rather fall by the way. (Tho you could say a boat with optimal broach resistance is less likely to find itself beam to a breaking wave, so the hydrodynamics are still worth considering.)

Classic wave theory has the water molecules moving in a circle. The implication of this is that on the face of a wave, "down" as measured by say a pendulum, is normal to the water surface. This continues until the wave is steep enough that the rotation can no longer be circular as the accelerations required are too great, the water slips and spills down the face - it breaks. A ballasted monohull with no mass (curious concept...) would roll so that it was always unheeled with respect to the water surface. Of course its real mass and moment of inertia in roll resists this cyclical motion - one reason why a mastless boat may roll over more easily. Once the wave breaks there are many dynamics involving the boat's characteristics in play. At least that is my understanding of it. 

Keeping the pointy end down the wave of course helps, but with large enough waves, pitchpoles have the same physics, and the greater longitudinal stability only hurts in that case. 

 

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21 minutes ago, Panope said:

I like that Idea.  

A recreation of the '82 Cabo disaster.

If I remember correctly, most of boats that did not drag ashore were using CQR and Bruce.

Ugh!  It’s becoming, like everything, an anchor thread!!! :-) :-)  :-)  Everyone needs a good one. 

 

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9 minutes ago, Jud - s/v Sputnik said:

.....

that makes me curious - how much empirical testing of procedures like that are done in climbing?  And are the 'bottom quartile' of climbers more knowledgeable with better judgement than the similar sailors?

to my uninformed eye, that particular anchor seems dependent entirely on the ice quality. Which he does not really mention/discuss (other than it should be dry so you can recover the rope).  And I personally would be reluctant to give that sort of equivalent direction to sailors because someone would try to follow it in the equivalent of obviously bad ice.

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35 minutes ago, estarzinger said:

that makes me curious - how much empirical testing of procedures like that are done in climbing?  And are the 'bottom quartile' of climbers more knowledgeable with better judgement than the similar sailors?

to my uninformed eye, that particular anchor seems dependent entirely on the ice quality. Which he does not really mention/discuss (other than it should be dry so you can recover the rope).  And I personally would be reluctant to give that sort of equivalent direction to sailors because someone would try to follow it in the equivalent of obviously bad ice.

Pretty much all ice gear falls under the category "psychological protection." Maybe it'll catch a fall, probably it won't, can give the leader a sense of comfort having something to clip a rope to. Ice climbers are a special bunch.:unsure:

Once you enter that world, you are buying into such a large carton of misery, self-abuse, risk, uncertainty, and disappointment that mere shitty gear placements are the least of your problems. Reading horror stories of climbers burrowing thru summit mushrooms in Patagonia, you're like: Well yeah, you bought the ticket my friend. ;)

IMG_0340

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5 hours ago, estarzinger said:

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

OK, so let me phrase it in a non absolute way. Designers of "proper lifting keel" boats warn you that it is unsafe to lift completely the keel except in sheltered waters so I wouldn't do it.

Like most Frenchmen, I have never ever reached the Southern seas. I also try to avoid storms, the scariest breaking waves I've seen were in 30 knots established in the Bay of Biscay where the seafloor rises suddenly from deep ocean to continental shelf and that was scary enough for me, I've run once ahead of bad weather in 35 knots of wind but that was along the Southern coast of Brittany where the sea is well mannered so although the swell was big it wasn't dangerous at all (thanks god as that was on a boat designed for inshore racing, we were young and foolish and took the kite down when got worried of burying the bow at the bottom of a wave!) so you can call me inexperienced of "proper 10m breaking waves" if you want. Nevertheless like many Frenchmen of my generation, I've learnt to race on a boat with a lifting keel (First class 8) and I know from experience that when you lift the keel the boat completely looses its stiffness and morphs in a boat which is somewhere in between a 505 and a keelboat! I will let you experiment alone offshore what it feels like but don't count on me to crew as I don't have the skills to keep the thing upright in breaking waves! Having raced said "Class 8" in heavy air, I know about the dynamics of these keels and this is why I said that raising the keel sometimes increases directional stability but lifting it completely in heavy seas would terrorise me. 

As for fin keels downwind in bad weather, most people here just get the storm jib up, as long as you keep the speed up, steer the boat, it is very unlikely that you broach. Most of these lightish offshore fin keel boats have a big NKE hydraulic autopilot with a "true wind angle" mode for a reason...

 

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6 hours ago, estarzinger said:

There is a risk of 'knock over' (eg 70-90 degrees) with almost all designs (in breaking waves). And you build your boat for the south just assuming you are going to get knocked over every couple years (at the very least least).  Empirically it seems (with a high degree of variability and noise) that the boats with board up may get knocked over more frequently but get knocked down (>90 degrees) less often than deep keel boats. 

I would think with a centerboard boat the risk of capsize would be minimized in breaking waves with the board up for the simple fact the boat would skid when hit broad side.  I don't have experience with a cruising centerboard boat in those conditions so it's just conjecture on my part.  Of the one design boats I've raced we always pulled up the centerboard when deep.  If some bite was needed when broad reaching we added maybe 1/4 board.

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On 5/13/2021 at 7:11 PM, accnick said:

Back in the mid-1970s, when my wife and I and several of our friends first lived on boats, we used to say "when the revolution comes, we are ready to get away."

I was living in NYC on 9/11. I heard about the attack within a few minutes of the first plane, friend phoned me. The first thing I did was mentally review the location of the sailboat fleets on Manhattan - no way I was getting stuck on that island! Then we went to the bank and got $10,000 cash and my wife and I carried 10 gallons of drinking water into our cave in the sky and filled both bathtubs as the authorities closed the bridges and tunnels. We waited to see if there were more attacks - anything else, we'd have grabbed a boat and left.

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On 5/13/2021 at 7:13 PM, estarzinger said:

one of our approaches to Bermuda, the night before landfall we saw a sail on the horizon (sailing 90 degrees to our course).  He called us up on the VHF and said 'do you know where you are? I'm trying to get to Bermuda but my GPS went out 2 days from Montauk'. 

One of my favorite historical factoids is that back in the days of sailing navies before Harrison made a reliable chronometer, the British Navy had standing orders not to spend more than two weeks looking for Bermuda. If they couldn't find it, carry on to the next destination in their orders! Sure you could get on the right latitude and sail back and forth, but not as easy it sounds in a square rigger.....

I also had a similar experience - enroute from Antigua to Columbia in the vicinity of the ABC islands a sail in the distance raised us on VHF and asked if we had a chart of Curacao. I didn't, but I had a Pilot with a written description of the approaches and harbor navigation and I dictated it to him over the radio.....

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1 hour ago, Panoramix said:

 Designers of "proper lifting keel" boats warn you that it is unsafe to lift completely the keel except in sheltered waters so I wouldn't do it.

Can you provide links to direct quotes of knowledgeable designers saying that?  I would love to read them, see what detail and context they provide.  I am sincerely interested in educated insight about this. 

One of my good friends sails a boat with what I think even you might consider a 'proper lifting keel'  - 2.7m draft when it is down, 39% ballast ratio.  They run with it up. And they have huge offshore experience (even more than I do).  But their hull shape is NOT the vendee/open shape - and perhaps that makes a difference idk - I would be interested in learning.  I actually would have thought the Vendee/open shape would give more initial stability so would be better rather than worse with the keel up.

 

 

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On 5/13/2021 at 7:29 PM, Jud - s/v Sputnik said:

I’ve nothing but huge respect for those who can cross oceans using a sextant (or none at all, i.e., using natural navigation).  And I think it’s a way to connect with the cycles of your environment too, which ain’t a bad thing :-)

I just use my sextant to keep my GPS honest these days....it's also fun to see how close I can get. Steadily inside 3 miles (and often inside 2) with waves under 6', with the error growing with sea state after that. 

By complete coincidence I was in Cape May NJ coastal hopping North from FL on May 17th, 1984 when Marvin Creamer sailed in, completing his circumnavigation with no instruments whatsoever - not even a compass. Amazing sailor, fun talking with him! He told us he had expected to arrive quite a few days earlier, but when he took a left to close land he found he was much further offshore than he estimated! Nailed the latitude though!! 

In that same boat as the above story in August 1983 I sailed out of Baiona, Spain heading South to Lisbon, and a few hours out of port became really ill with what turned into a full blown case of food poisoning. I was the only one on the boat who could navigate. I gave the crew a course that diverged slightly to seaward from the rhumb line to Cape Roca above Lisbon and told them on no account to sail to port of that course. Then I went below to die. When I could once again drag my carcass on deck I shot a noon sight to get latitude, and we were at Lisbon near enough, so we took a left. I studied the log and figured we were 30 miles offshore. Well, the crew had been a little overenthusiastic following instructions - we were 90 miles offshore, took us a long time to get into Lisbon!

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24 minutes ago, estarzinger said:

 

It tends to be written in the boat user manual, I couldn't find the Pogo 12.50 user manual online but I found the extract about the keel for the RM 10.50 : https://rm-asso.org/utav/fichiers/QR.pdf

It is a vertically lifting keel but the Physics are the same, it is in French but clearly says "When sailing the keel must be down" (the bit below "Avertissement"). When I was racing "Class 8" we were careful about this, "I forgot the keel" was even a classic joke to scare the skipper but we were young and facetious!

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8 hours ago, estarzinger said:

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

The big difference between the Pogo and a lift keel is where the ballast position ends up.

"Lifting" a board on doesn't move the ballast fore or aft. The 12.50 'swings' the ballast aft 3mtrs.

Pogo's standard advice is keel must be down when sailing, which makes a lot of sense selling to a generic level skill set. Quietly they will tell you running with the keel up is fine if you want to, just don't go broad reaching due to the loads this puts on the keel head.   

After hitting a whale several times bigger than the boat I'm a huge fan of the 'crumple zone' the swing keel design gives you. Now a lift keel with the same anti crash characteristics as a swing keel (and no intrusion into the cabin space) would be awesome, but the physics does my head in.

 

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16 minutes ago, Panoramix said:

 RM 10.50

Can you find a stability curve for the RM10.50?  I would be curious how it compares to a Pogo curve, which honestly does not look so terrible with the keel up - more tender certainly, but I also note shaggy's comment that it moved weight distribution aft, which I think, (again I'm not at all any expert on this aspect) would help running in strong stuff - when I was racing light boats we certainly tried to trim weight aft in those conditions..

I would be quite interested if you can find any discussion which included a 'designers comments', say in an interview with an experienced sailor. That would likely be more insightful than a warning in a user manual, which often have a huge legal CYA component to them. I can well imagine the lawyers wanting this to say 'put the damn keel down when you are sailing', and that that might or might not represent best practice in the edge case (downwind in big waves) which most used dont get themselves into. 

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46 minutes ago, shaggybaxter said:

. Quietly they will tell you running with the keel up is fine if you want to, just don't go broad reaching due to the loads this puts on the keel head.   

we really need you to get your boat back and do a series of test runs in the gulf stream with 50 NEly :blink:

We can get DDW to instrument up the boat so we get good big data comparisons of yaw and roll.

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This is sort of on my list of things to do. One side benefit of (at least the Raymarine) modern autopilot is the flux gate compass sensor has been replaced by a 9 axis MEMs sensor, and all of the effort needed to develop artificial horizon software was long ago sunk by the drone and cell phone folks. So roll, yaw, pitch, and heading are available at a very high frequency on the NMEA 2K bus. As well rudder angle. There are now cheap devices that record this continuously. My boat is clearly not an UL lifting keel, but it should be easy for someone to collect the data. Go out in the next F8 with your Pogo, run for awhile keel down, then keel up. You could compare roll and raw excursions against rudder angles and probably learn something. 

For the ultimate question, we would need 100 volunteers in 100 Pogos, half with keel up and half down, running in extreme conditions and see how many in each reference class die. But that is an experiment unlikely to get funding. 

I'm a little curious about the structural integrity of keel up operation. Not familiar with the details of the keel  mechanism, but for some that I am familiar with, keel up would not be great. For that matter on some keel down isn't good either, but that is a separate keel integrity discussion. 

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1 hour ago, estarzinger said:

Can you find a stability curve for the RM10.50?  I would be curious how it compares to a Pogo curve, which honestly does not look so terrible with the keel up - more tender certainly, but I also note shaggy's comment that it moved weight distribution aft, which I think, (again I'm not at all any expert on this aspect) would help running in strong stuff - when I was racing light boats we certainly tried to trim weight aft in those conditions..

I would be quite interested if you can find any discussion which included a 'designers comments', say in an interview with an experienced sailor. That would likely be more insightful than a warning in a user manual, which often have a huge legal CYA component to them. I can well imagine the lawyers wanting this to say 'put the damn keel down when you are sailing', and that that might or might not represent best practice in the edge case (downwind in big waves) which most used dont get themselves into. 

I remember seeing it written in Voiles et Voiliers in an artcle comparing shallow draft options where architects were interviewed but I would need to spend a lot of time to find it. I tried briefly to Google it earlier without success.

May be we are collectively wrong but here it is common knowledge.

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7 hours ago, DDW said:

The dynamics of breaking waves calls into question the notion of "tripping" on the keel. I think the Southhampton studies illuminated this. Simplistically, the boat is turned over by a water surface that remains still and parallel to the waterline in the boat's frame of reference. Tripping while broaching has different dynamics.

Yes the whole tripping on the keel is just a meme that perpetuates. It's an urban myth that circulates with no basis in fact.  It's more accurate to say that boats trip over their deck edge, not their keels.

It's not the wave orbital that inverts the boat it's the breaking wave jet. The orbital is not a significant factor.

The boats that were noted by various researchers as completely immune to capsize at one end on the design spectrum were narrow, very heavy and with a massive keel area. The ratio of immersed profile area to topside area is also significant in inversion dynamics.

There's a lot of data and research online now by a variety of researchers with access to facitlies with wave tanks. In the UK, various at Southhampton, Japan (Osaka uni, Nomoto), Netherlands (deKat), and Australia (Renilson). 

 

 

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32 minutes ago, MikeJohns said:

 

.......The boats that were noted by various researchers as completely immune to capsize at one end on the design spectrum were narrow, very heavy and with a massive keel area. The ratio of immersed profile area to topside area is also significant in inversion dynamics........

 

 

 

Just to clarify, are we talking hulls like the old pilot cutters and "plank on edge" cutters?

Lore as it that they could stand to ANY weather.  Maybe true? 

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A lot of this recent discussion is, I humbly admit, going over (well, has already gone :-) ) over my head.

Maybe I need to dig into “Oceanography and Seamanship” (which might more properly be titled “Physical Oceanography and Seamanship”, since it deals with that particular branch of oceanography as applied to seamanship, and not the other two branches, chemical and biological oceanography).

I got the book a while ago and never started it.  Written by a prof at Scripps Institute of Oceanography, who’s been to sea in everything from ships to small boats - the book ranges from understanding global ocean circulation and wave action on shorelines, to yacht design and stability characteristics, etc.

Looks like a serious but interesting read - interesting for sailors because it’s applied (physical) oceanography.  I’ll report back when I’m done and hopefully add something to this discussion on stability.....or not... :-)   (This second edition was issued after the Fastnet Race disaster, so incorporates some observations from that.)

 

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34 minutes ago, Jud - s/v Sputnik said:

 Dorm . . . . 

Dorn is interesting

as is the Wolfson Unit (and other) tank testing.

Such 'theoretical' stuff needs to confirmed in the 'real world'.

In this case - we seem to have two different schools of 'real world' experience with lifting keels - from the South, and what Panoramix describes as 'common knowledge' in France.  That does not make either necessarily wrong - I would guess they represent quite different sets of designs and quite different common conditions.

As to keel tripping . . . as I said above, the more important/primary issue to me seems to be directional stability on steep wave faces.  I guess I think that is clear.  But I personally would not be comfortable writing 'tripping as a secondary/contributing cause' off as a complete myth - perhaps, but it seems too facile for a complicated hydrodynamic situation.

My understanding of the " narrow, very heavy and with a massive keel area" was that they did not stay inverted; NOT that they were immune to knockdown.  In fact, I believe the conclusion was definitive that ALL designed can be rolled.

Jud - I actually dont know - is your boat a lift keel? If so, what sort of design for the keel and housing?

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2 hours ago, DDW said:

I'm a little curious about the structural integrity of keel up operation. Not familiar with the details of the keel  mechanism, but for some that I am familiar with, keel up would not be great. For that matter on some keel down isn't good either, but that is a separate keel integrity discussion. 

Yep, my dislike about keel up mode under sail as it seems illogical from a forces point of view. My keel head is only a single bolt through an eralyte bearing, so the mating of the keel box and head have to be structural, ie: it must 'fix' the keel in place.

In the perfect world, if I was sailing keel up I'd want the same structural integrity from the keel /keel box, and that, I assume, would be a tall order when supporting the resultant forces from a couple of ton near horizontal in the water.  

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Apologies for the thread drift, this is a really good thread. 

 

      

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1 hour ago, estarzinger said:

As to keel tripping . . . as I said above, the more important/primary issue to me seems to be directional stability on steep wave faces.  I guess I think that is clear.  But I personally would not be comfortable writing 'tripping as a secondary/contributing cause' off as a complete myth - perhaps, but it seems too facile for a complicated hydrodynamic situation.

As far as I know, it's been common lore for 50+ years(?) that bluewater multihulls, when sailing downwind or in rough seas from unfavorable directions, will raise their main (forward, deepest) daggerboard(s) to improve directional stability.  It has no effect on their righting moment since they have no ballast.

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1 hour ago, ProaSailor said:

As far as I know, it's been common lore for 50+ years(?) that bluewater multihulls, when sailing downwind or in rough seas from unfavorable directions, will raise their main (forward, deepest) daggerboard(s) to improve directional stability.  It has no effect on their righting moment since they have no ballast.

My experience with my 40' cat with daggerboards and no stub keels was that, under power with the boards up, there was noticeably less directional stability (i.e. the helmsman or autopilot worked much harder to maintain a stable course... even in flat water).  Consequently, I always ran with about half boards when under power or running downwind.

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2 hours ago, Panope said:

Just to clarify, are we talking hulls like the old pilot cutters and "plank on edge" cutters?

Lore as it that they could stand to ANY weather.  Maybe true? 

 

The Bristol channel pilot cutters particularly, noted historically and by more modern researchers as being a capable and seaworthy craft. They needed a turn of speed but still able to hold station in rough weather. Variations on the full keel such as cutting away the forefoot were tried but weren't popular with the operators.

The type was easily handled  and had an extreme operational requirement;  able to face the full force of an Atlantic gale and could be hove-to on station in all weather while awaiting an incoming ship and getting the pilot on board. 

None was ever noted to have been lost to the sea, only to collision usually being run down by a ship they were hove-to waiting for !

Also Andy Claughton of Wolfston in his "Investigation of stability of sailing yachts"  and his other "yachts in breaking waves" noted with repeated tests that the full keel models surfed with excellent directional control in large breaking waves. They also showed no tendency to invert in breaking waves that well exceeded the beam, waves that inverted every fin keel models tested, usually with a height close to the crafts beam .

It dispelles "keel tripping" as a factor.

In the 98 Sydney Hobart coroners inquest Andy Claughton was an expert witness. He upseat a few people with his comments that people had been told often enough specifically what makes a boat un-seaworthy and that they just don't seem to get it !  

 

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4 hours ago, MikeJohns said:

It's not the wave orbital that inverts the boat it's the breaking wave jet. The orbital is not a significant factor.

Of course the orbital would not invert the boat, but it will heel it some amount - and in a modern hull form that could be quite a bit - making it more vulnerable to the jet. Very hard to separate the two factors, as the orbital is always present, so "not a significant factor" is a difficult thing to demonstrate. 

There are so many differences between a BC cutter and a modern hull form, it would be hard to single out one as the cause of any difference in characteristics. Among them the beam is narrow compared to length and roll moment of inertia, so wave height compared to beam may lack something as a metric to compare. Another might be keel depth which might be double on the modern hull form. 

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3 hours ago, estarzinger said:

Jud - I actually dont know - is your boat a lift keel? If so, what sort of design for the keel and housing?

No, not a lift keel.  (Fortunately - as convenient as those maybe, seems like a potentially big maintenance problem). Big fat fin keel.  (With features both desirable —holds lots of fuel; supports boat standing up, with drying legs— and undesirable: it’s not exactly a modern foil shape with lots of lift :-) )

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7 hours ago, estarzinger said:

In this case - we seem to have two different schools of 'real world' experience with lifting keels - from the South, and what Panoramix describes as 'common knowledge' in France.  That does not make either necessarily wrong - I would guess they represent quite different sets of designs and quite different common conditions.

Don't get me wrong, with a centreboard, I would lift it as people who owns centreboard boats do... I am aware of the interest of minimising "foil area" in big weather, it is just that when it is a matter of choosing between righting moment and "less foil in the water", I choose righting moment.

The concept of adapting the centre board to the conditions is also present here, a 1980s boat that still sells at high prices pushed the concept far and is well liked :

5dd34c5039819f3668f5c1ac.jpg

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8 hours ago, MikeJohns said:

Also Andy Claughton of Wolfston ....  showed no tendency to invert in breaking waves 

I

Really, (as I said above) you are rather overstating that - they concluded that all the designs could be rolled  - here is a scan of the key section of the summary . . . 

roll.jpg.86326807450b9d8cd1cb19dcdccd845a.jpg

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10 hours ago, MikeJohns said:

Also Andy Claughton of Wolfston in his "Investigation of stability of sailing yachts"  and his other "yachts in breaking waves" noted with repeated tests that the full keel models surfed with excellent directional control in large breaking waves. They also showed no tendency to invert in breaking waves that well exceeded the beam,

So - I've owned such a boat (see 1982 picture below) and it was 10 tons of an utter pig to sail for 3,000 miles. I never had her in breaking waves, but I clearly recall that dead downwind in rough weather, the waves overtaking the boat pushed the rudder around and made the tiller a menace - you couldn't really hold it against the water pressure, and the boat became progressively harder to steer. 

And (I think for the second time in this thread) I'd point out the 1957 experience of Miles & Beryl Smeeton in their 46' full keel ketch Tzu Hang who pitchpoled the boat twice in two successive attempts to round Cape Horn, only succeeding on their third 1968 try (shakes head....). Here is a link to an article about it:

https://dragdevicedb.com/drogues-on-monohulls/dm-1-monohull-bermuda-ketch

Also worth noting that on their first try they had with them John Guzzwell, who amateur built a 20' Laurent Giles yawl and leaving Canada in 1955 sailed it singlehanded around the world in stages over four years.

These folks along with Humphrey Barton (1950 Atlantic crossing in a Laurent Giles Vertue 25), the Hiscocks (first trip around in 1952 in an engineless 30' Laurent Giles sloop), and a handful of others are some of the real pioneers of small boat ocean cruising back when people doubted it was possible - they tend to be forgotten behind the more publicized younger sailors who stood on their shoulders. 1382670370_Vaigerbow.thumb.jpeg.e7566f2976b38c6b4b95323d0d9bbafd.jpeg2051177774_Vaigerstern.thumb.jpeg.c8af4bfdd5bdce53ed9acb23c78941c8.jpeg

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Please forgive the diversion. I can certainly see how a following wave would yank that rudder around like a barn door in a hurricane. I wonder if a semi balanced spade would fare better? 
 

OK, I’ll shut up now. Great thread BTW.

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13 hours ago, ProaSailor said:

As far as I know, it's been common lore for 50+ years(?) that bluewater multihulls, when sailing downwind or in rough seas from unfavorable directions, will raise their main (forward, deepest) daggerboard(s) to improve directional stability.  It has no effect on their righting moment since they have no ballast.

We've found our Atlantic 57 steers better with a little daggerboard down off the wind. 

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12 hours ago, MikeJohns said:

Also Andy Claughton of Wolfston in his "Investigation of stability of sailing yachts"  and his other "yachts in breaking waves" noted with repeated tests that the full keel models surfed with excellent directional control in large breaking waves. They also showed no tendency to invert in breaking waves that well exceeded the beam, waves that inverted every fin keel models tested, usually with a height close to the crafts beam .

One more full keel story. My first real offshore trip was on an amateur built engineless steel Thomas Colvin 48' Pinky Gaff Schooner called Papillon. I joined the owners in the Fall of 1979 in Southwest Harbor, ME to sail to Cape Henry. We sailed out into a 3-day SW'ly blow (hey, I wasn't the captain, but I did see and not like the forecast and went on anyway....).

When it got too rough to make headway we hove to with a reefed foresail on a starboard tack. As the wind built we furled the foresail, hove to under bare poles - but really we were more lying ahull at that point. At the height of the storm there was so much water falling on the boat that it was basically 2-3 feet underwater for about five or six hours, never clearing the decks. If we'd blown a hatch off we'd have been fighting for our lives - 1 point for steel. Throughout the experience I always felt like the boat was managing OK, the motion while violent made sense to me - except for about two hours at the utter peak when it seemed to me the boat was starting to struggle a little to stay rightside up in the bigger waves/heavier water.

The weather subsided, the captain shot a few sun sights - we'd missed Cape Sable by 30 miles, and we were 150 miles closer to Bermuda than Cape Henry. Like 1/4 of the way across the North Atlantic! Everything that had been lashed on deck (there was a lot of stuff!) was gone except the tender.

So we headed for Bermuda. When we got there, turns out the steel pipe masts were too heavy, the boat just fell over close hauled, and we couldn't make progress upwind at all to enter the harbor. We attracted attention with a signal mirror to shore, and the Coasties came out and towed us in.

How much wind/wave? Really I've no idea. By FAR the roughest sustained weather in my subsequent 70K+ miles of sailing. As a swag I'd say we saw lots of 50 knots/20' sustained, at least some 60 knots/25' sustained and definitely gusts to 70+ and some much much bigger waves mixed in. We basically left the boat completely to herself, and she managed.

In 2011 the owner/builder's son put her on the beach at Fire Island, though I understand she was subsequently salvaged and refitted.Donna_Boat_Color.jpeg.5ba0489dfb8b4bf981ff314f0d5e5ba7.jpeg

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1 hour ago, CapDave said:

We've found our Atlantic 57 steers better with a little daggerboard down off the wind. 

I'm not surprised.  Raising a long (9 feet draft) daggerboard to match rudder draft reduces draft and wetted surface substantially.  The significant feature is that very little mass moves in the daggerboard, which could be done on monohulls too, but is a given on multihulls.

Heavy Weather Strategies When Sailing a Catamaran
https://www.sailmagazine.com/multihulls/heavy-weather-strategies-when-sailing-a-catamaran
PETER JOHNSTONE - UPDATED:MAR 27, 2019 - ORIGINAL:JUL 30, 2014

Quote

On a performance cat, you can raise both boards and experience perhaps the greatest days of your sailing life. Speed is your friend. A modern performance cat’s bows will rise as she gains speed, and there are no downsides to going faster. The closer you sail to the wave train’s speed, the smoother the ride becomes, and the less chance you have of experiencing a large wave impact. The sail selection can be a deeply reefed mainsail or a jib sheeted to the outboard rail. Even in 50-60 knots of wind, the ride will be smooth and comfortable as you sail at 15-25 knots. Always check helm balance to keep the rudders and pilots lightly loaded.

 

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1 hour ago, ProaSailor said:

I'm not surprised.  Raising a long (9 feet draft) daggerboard to match rudder draft reduces draft and wetted surface substantially.  The significant feature is that very little mass moves in the daggerboard, which could be done on monohulls too, but is a given on multihulls.

Heavy Weather Strategies When Sailing a Catamaran
https://www.sailmagazine.com/multihulls/heavy-weather-strategies-when-sailing-a-catamaran
PETER JOHNSTONE - UPDATED:MAR 27, 2019 - ORIGINAL:JUL 30, 2014

 

The roughest weather we've seen on the A57 was off Cape Cod on our very first trip with the boat enroute from GA to Halifax in June '19. Double reefed main, double reefed genoa, 100 AWA, 25-30 AWS with higher gusts, waves maybe 12' and building. Boards were up, we were sailing high teens to low twenties, peaking at 23. Bows were high, deck was dry, helm was finger tip pressure with complete immediately responsive control, ride was on rails. We put the autopilot on and enjoyed the ride for a few hours until conditions moderated. With more experience on the boat now I'd have the staysail up instead of the reefed genoa, and I'd try a little daggerboard.

My last boat (Oyster 61) was not much fun in those conditions - the helm forces on the unbalanced barn door rudder behind the skeg were extraordinary, and humans/autopilots struggled. The fix was to put the main away and sail more slowly with headsails only. But I swore it would be the last boat I ever owned without at least a partially balanced rudder. Sorry Holman & Pye!

To PJ's "Park Your Cat" strategy - we have experimented with heaving to with just a close sheeted staysail with boom amidships and helm tied to round up. The boat and the sail both sit very quietly, slowly forereaching which we could tune with traveller position. I might try his version with the Main sheeted tight and traveller downwind, but I wonder if the boat won't develop more headway and do more of an S shaped course and periodically luff the sail??

 

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19 hours ago, Jud - s/v Sputnik said:

A lot of this recent discussion is, I humbly admit, going over (well, has already gone :-) ) over my head.

Maybe I need to dig into “Oceanography and Seamanship” (which might more properly be titled “Physical Oceanography and Seamanship”, since it deals with that particular branch of oceanography as applied to seamanship, and not the other two branches, chemical and biological oceanography).

I got the book a while ago and never started it.  Written by a prof at Scripps Institute of Oceanography, who’s been to sea in everything from ships to small boats - the book ranges from understanding global ocean circulation and wave action on shorelines, to yacht design and stability characteristics, etc.

Looks like a serious but interesting read - interesting for sailors because it’s applied (physical) oceanography.  I’ll report back when I’m done and hopefully add something to this discussion on stability.....or not... :-)   (This second edition was issued after the Fastnet Race disaster, so incorporates some observations from that.)

 

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Marvellous book - the findings regarding anchoring showing why pure chain makes no sense opened my eyes!

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32 minutes ago, CapDave said:

the helm forces

 

I have not understood why hull/steering balance and helm forces are (seemingly) not near the top of designer priorities. Nor why it is so rarely specifically called out in boat reviews and discussions.  It really is a super critical aspect of design.  And if you were thinking of buying a new boat, or getting a custom one done, it is very hard for the customer to get a good assessment of what the helm is going to be like.  (yea, take a sister ship out sailing, but how often are you given a chance to do that in hard enough breeze and waves to really see the helm loaded).

Next to the actual real world merits of various sail cloth, it is one of the things most hidden from the sailors until after they purchase. No-one seems to have incentive to be honest about it all.

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15 hours ago, Jud - s/v Sputnik said:

: it’s not exactly a modern foil shape with lots of lift :-) )

I raced (as bow and helm over various seasons) an  Aage Nelson design, originally designed with a 'cca' centerboard (eg a stubby fin with board that folded up into it).  For racing rule reasons (IMS) the owner pinned up the board for racing - it was way faster without the board than the IMS vpp thought.  But what surprised me was it was actually quite fast upwind boat for boat (putting the whole rating thing aside) with just the stubby keel.  One of my vivid sailing memories was helming in the block island race, upwind, and sailing right by boats which 'should have been' faster.  I was sort of 'on trial' that race to see if I was any good because they saw me as a cruising sailor who probably did not know how to go fast.  And the owner and core crew were watching this and saying WTF :) I had just spent 4 years full time offshore sailing a boat with a very similar keel which in fact gave me a shit ton of relevant helm experience - but even so I could never take full credit for that performance - the crew was great at trimming, the sails and bottom were in perfect shape, and the owner knew how to play the currents.  But it astonished me that the boat with that 'crippled' keel could even do it at all - I took away that foil design/performance was not soundbite simple.

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1 hour ago, CapDave said:

The roughest weather we've seen on the A57 was off Cape Cod on our very first trip with the boat enroute from GA to Halifax in June '19. Double reefed main, double reefed genoa, 100 AWA, 25-30 AWS with higher gusts, waves maybe 12' and building. Boards were up, we were sailing high teens to low twenties, peaking at 23. Bows were high, deck was dry, helm was finger tip pressure with complete immediately responsive control, ride was on rails. We put the autopilot on and enjoyed the ride for a few hours until conditions moderated. With more experience on the boat now I'd have the staysail up instead of the reefed genoa, and I'd try a little daggerboard.

Ya mon!  I can picture that so clearly... 

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1 hour ago, Knut Grotzki said:

pure chain makes no sense

Haven't read it, don't know his argument. But we broke our windlass 3 weeks ago and DHL is camping on the replacement in transit for 2 weeks now. So we've been using our backup which is all rope with a short chain leader. Forcibly reminded me of two great advantages of all chain - first, it's "no touch", which matters once you get over about 30-35 feet, hate getting my hands involved with the ground tackle. Second, it's "no chafe", which doesn't really matter around Antigua where we're anchoring on sand, but we're headed for Maine June 1, and I'm not so happy about anchoring on those bottoms with 15' of chain before the rope - so I hope DHL pulls their act together!!

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1 hour ago, estarzinger said:

I have not understood why hull/steering balance and helm forces are (seemingly) not near the top of designer priorities. Nor why it is so rarely specifically called out in boat reviews and discussions.  It really is a super critical aspect of design.  And if you were thinking of buying a new boat, or getting a custom one done, it is very hard for the customer to get a good assessment of what the helm is going to be like. 

Mine was a case in point. Custom design, when looking at the profile one of the first things I said was "the rudder does not have enough balance". It had about 10 or 12%. I was told I wasn't the NA with 30 years experience, I was paying for his expertise, and I should build it like he drew it and I'd be happy. I did build it that way but I was not happy. The boat had good control and balance, but required a lot of steering force sometimes. When I got it back to the builder where it was convenient, we deskinned the rudder and I redrew the profile with about 18% balance. Now the boat is fingertip light, a pleasure to helm anytime, and of course uses noticeably less power on the autopilot (which it is 98% of the time). 

There was a thread on it awhile back when I did it, one thing I remember from that thread is that many people conflate hull/rig balance and helm force. They are independent, though bad balance will illuminate high helm force because of the standing helm required. 

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10 hours ago, estarzinger said:

Really, (as I said above) you are rather overstating that - they concluded that all the designs could be rolled  - here is a scan of the key section of the summary . . . 

roll.jpg.86326807450b9d8cd1cb19dcdccd845a.jpg

 

Ok lets keep it simple and run with the discernible trends. (I'm sure you know all of this but for the thread).

The main point I'd really like to illustrate is that entrained mass and damping from a full keel were noteworthy in reducing the roll angle, not significant in causing it.

And again, a boat "Trips on it's deck edge" not significanty on it's keel. All boats can be knocked down.  Whether that progresses into a full loss of stability (inversion) depends on quite a lot of factors.

But simplistically, like the simple factors Andy was adressing to the S-H coroner :

Lower beam, larger keel area, heavier displacement, large roll inertia  and higher static LPS are all beneficial factors in seaworthiness.

 

 

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8 hours ago, CapDave said:

So - I've owned such a boat (see 1982 picture below) and it was 10 tons of an utter pig to sail

 

I've never liked heavy double enders either and I know the type. Look up Bristol channel pilot cutters for the other type mentioned.

As for Tzu Hang: Heavy weather technique has been a learning process,  prior experience was rare in small boats in the Southern ocean.  There will always be the 1/1000 wave lottery but you can stack the odds in your favor.

Now in a monohull we are supposed to surf the waves taking the wave on the stern quarter, and we preferably keep the boat moving well with a competent helmsman.   If that can't be done we don't lie ahull in survival seas only ever heave to. Smeeton didn't know any of this, nor did he have reliable weather forcasts.

 Your colvin pictured doesn't actually have much keel area at all !  Just a large lateral plane area. Always happy it was someone else not me that time !

A very seaworthy class was the British steel challenge boats. Moving well on from older trad designs.

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3 hours ago, MikeJohns said:

 

Ok lets keep it simple...

But simplistically...

 

too simple for a complex subject and in all likelihood thus misses quite important interactions.

Just to present an edge case - Large very lightweight multi-hulls with minimal keel area are actually quite 'seaworthy'.  And to present a dead center case - even right with-in the wolfson test they added (like doubled) keel area to the baseline fin keel models and it made "no discernable difference" to results.  The wolfsom report in fact specifically called out interactions between factor for the positive narrow/full results.

As a further 'complication', the wolfson results dont include any steering input, while in the real world we have steering, and generally there can be a meaningful difference in steering responsiveness between full keels and fin keels, which effects 'seaworthiness' in complex ways.

And I think it is too simple to answer the question I posed which started this - should the pogo run with keel up or down.  It is (essentially) the same area and same mass either way, just in a vertical or horizontal orientation - in one orientation you have better directional control and bow up trim, in the other orientation you have higher righting moment.  There are complex trade-offs and interactions involved in making that choice. In some seastates you might well want to do one thing and in another do the other thing (or even a setting in between)

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1 hour ago, MikeJohns said:

 Your colvin pictured doesn't actually have much keel area at all !  Just a large lateral plane area. Always happy it was someone else not me that time !

Tom's pinky schooner design is a long shoal draft keel. I have a full set of plans to build one, as does everyone with a copy of Tom's book, because he used it as his example of how to build a boat. Said it incorporated a lot of different things that were useful to illustrate.

So yeah, nothing like a fin keel of any description.

I have a copy of pix of that boat embedded in the beach and being excavated & dragged off for a rebuild. Got to love a steel hull to survive that. The rig was still up too.

I have steel tube masts FWIW. And galvanised steel wire standing rigging but probably if/when it comes time to replace it I'll go to Dyneema.

FKT

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4 hours ago, estarzinger said:

too simple for a complex subject and in all likelihood thus misses quite important interactions.

Just to present an edge case - Large very lightweight multi-hulls with minimal keel area are actually quite 'seaworthy'.  And to present a dead center case - even right with-in the wolfson test they added (like doubled) keel area to the baseline fin keel models and it made "no discernable difference" to results.  The wolfsom report in fact specifically called out interactions between factor for the positive narrow/full results.

As a further 'complication', the wolfson results dont include any steering input, while in the real world we have steering, and generally there can be a meaningful difference in steering responsiveness between full keels and fin keels, which effects 'seaworthiness' in complex ways.

And I think it is too simple to answer the question I posed which started this - should the pogo run with keel up or down.  It is (essentially) the same area and same mass either way, just in a vertical or horizontal orientation - in one orientation you have better directional control and bow up trim, in the other orientation you have higher righting moment.  There are complex trade-offs and interactions involved in making that choice. In some seastates you might well want to do one thing and in another do the other thing (or even a setting in between)

You need to look at Andy's papers rather than just the commercial Wolfston report. He used full wireless remote steering and ran the models at a variety of angles to the breaker. They were underway and under full steering control when hit.

I know it's a complex subject, I keep stating that myself.  But in defense of the science behind predictions of coupled motions are well understood and described. Computer generated models are now very useful and are used extensively and validated.

The Pogo is a very light beamy boat.According to research beam is the most specific risk factor in inversion.  The Righting moment curve shows for the keel up is 100 degrees for whatever load state the designer chose and since that's unspecified you can presume it's significantly lower for sailing trim.

Keel down will  increase RM increase LPS and increase Roll gyradius, so why would you even consider keel up ?

 

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On 5/15/2021 at 7:58 PM, MikeJohns said:

Yes the whole tripping on the keel is just a meme that perpetuates. It's an urban myth that circulates with no basis in fact.  It's more accurate to say that boats trip over their deck edge, not their keels.

It's not the wave orbital that inverts the boat it's the breaking wave jet. The orbital is not a significant factor.

The boats that were noted by various researchers as completely immune to capsize at one end on the design spectrum were narrow, very heavy and with a massive keel area. The ratio of immersed profile area to topside area is also significant in inversion dynamics.

There's a lot of data and research online now by a variety of researchers with access to facitlies with wave tanks. In the UK, various at Southhampton, Japan (Osaka uni, Nomoto), Netherlands (deKat), and Australia (Renilson). 

 

 

The idea that a boat with centerboard up will skitter to leeward and frustrate the force of a breaking wave goes back a long way, at least to Commodore Monroe and the original Presto. Phil Bolger quoted it a couple times, but he also pointed out that there is a limit. He wrote "Look at a toy boat in surf."

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6 hours ago, MikeJohns said:

Keel down will  increase RM increase LPS and increase Roll gyradius, so why would you even consider keel up ?

 

because it increases steering directional control and bow up trim.  Both of which have some value.

look - just for argument purposes would you take .01% extra righting moment or AVS but be willing to give up 75% directional control?  Ofc you would not.  It is a trade-off and at some values in some sea states the trade-off is worth making in one direction and as some other values is worth going the other way.

I ask the question because very experienced people I know sail ballasted-board swing keel boats that way (running keel up), and I was curious what the empirical wisdom was for the pogo - which is certainly a different design than the boats I refer to but shares a lot of traits.  I 'think' the answer is we here don't know.

 

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