# Heeling



## jho11381 (Dec 15, 2011)

What is the maximum heeling of a Catalina 22 with a swing keel before it capsizes?


----------



## nolatom (Jun 29, 2005)

According to a Googled comment, the truth of which I know not, around 95 to 100 degrees:

Google


----------



## bobperry (Apr 29, 2011)

JH:
If I were to guess I'd say 105 to 107 degrees. I think you should call Catalina to get an accurate answer. They will know.


----------



## peterchech (Sep 2, 2011)

More important may be at what angle of heel does righting moment start to drop off. On many keelboats, after about 60 degrees the righting moment quickly disappears. Fortunately, so does the effectiveness of the heeled sails, but a spinnaker not so much...


----------



## CapnBilll (Sep 9, 2006)

Unless the swing keel is locked in place once you get past 90 it will retract, thats one of the many reasons why it is better to have a fixed keel on the open ocean.

The boat may still have positive righting arm, but whatever force brought you to 90 will still be there minus the righting arm of the swing keel. Because of friction it may take a few degrees past 90 to make it retract fully, but that depends on whatever inertial forces are in play.


----------



## bobperry (Apr 29, 2011)

Peter:
Generally the loads on the rig fall of once you heel past 30 degrees. But you are correct. A spinnaker can continue to stay filled well past 30 degrees. I think it is prudent on any boat to operate it at heel angles less than 30 degrees. It's safer and faster that way.


----------



## RichH (Jul 10, 2000)

CapnBilll said:


> Unless the swing keel is locked in place once you get past 90 it will retract, thats one of the many reasons why it is better to have a fixed keel on the open ocean.
> 
> The boat may still have positive righting arm, but whatever force brought you to 90 will still be there minus the righting arm of the swing keel. Because of friction it may take a few degrees past 90 to make it retract fully, but that depends on whatever inertial forces are in play.


VERY good advice for keeping the swing keel LOCKED on a C22. Once the boat goes beyond 90° the keel 'can' self-retract, and the boat can then 'invert', eventually with the mast 'straight down in the water'. 
I did a rescue on a C22 a long time ago, with the sailor still inside the inverted hull. Needless to say the rescue was 'interesting' as the sailor was a non-swimmer and had his PFD on .... and was thoroughly 'terrified'.


----------



## peterchech (Sep 2, 2011)

RichH said:


> VERY good advice for keeping the wing keel LOCKED on a C22. Once the boat goes beyond 90° the keel 'can' self-retract, and the boat can then 'invert', eventually with the mast 'straight down in the water'.
> I did a rescue on a C22 a long time ago, with the sailor still inside the inverted hull. Needless to say the rescue was 'interesting' as the sailor was a non-swimmer and had his PFD on .... and was thoroughly 'terrified'.


Does a C-22 have positive flotation?


----------



## peterchech (Sep 2, 2011)

bobperry said:


> Peter:
> Generally the loads on the rig fall of once you heel past 30 degrees. But you are correct. A spinnaker can continue to stay filled well past 30 degrees. I think it is prudent on any boat to operate it at heel angles less than 30 degrees. It's safer and faster that way.


Not to mention if the momentum of the heeling force causes a knockdown, filling the sails with water...

Bob, I never understood why righting moment drops off before 90 degrees of heel. Shouldn't it get higher and higher up to 90 degrees? Essentially, the keel is acting as a fulcrum, with the center of buoyancy of the hull acting as the pivot point. This should mean righting moment increases up to 90 degrees, no less than that... right?


----------



## Barquito (Dec 5, 2007)

> Does a C-22 have positive flotation?


No. Keelboat sailors get in trouble on the C22 if they are not prepared to ease sheets in a puff. In strong winds the C22 behaves more like a dinghy. In a knock-down water could enter quickly through the ventilation ports on the stern quarters, unlatched lockers, and open hatch boards. OTOH, they tend to round-up quickly when heeled. So, the most likely scenario is you get hit with a sudden puff, heel quickly, fall to the cockpit floor, get up to find you are sitting pretty, head-to-wind. (don't ask me how I know)


----------



## bobperry (Apr 29, 2011)

Peter:
I don't have an easy answer for you. It all depends upon the shape of the hull and where the VCG is. If you take a wide, light and flat bottomed boat with a relatively high VCG the Rm will drop off quickly above around 60 degrees. But if you have a boat that is long , heavyish and narrow with a nice low VCG the RM will stay strong well past 60 degrees.

I have avoided writing an article on stability. It's complex. It sure is hard to explain without drawing diagrams. I would warn against making general statements regarding stability. Location of VCG is very important. I can make that general statment.


----------



## CapnBilll (Sep 9, 2006)

In a sailboat you have two opposing forces, the righting moment of the keel minus the destabilizing moment of the mast and rigging. Plus or minus the righting moment of the buoyancy of the displaced volume of the hull, usually a wineglass shape. which means that as the boat heels the volume of displaced water increases due to the flairing of the hull, but in most boats once you get the hull right on it's edge the flairing stops and the boat most resembles a triangle on the next corner. The mast is on the longest lever, and the deck is flat and displaces less water than the hull.


----------



## bobperry (Apr 29, 2011)

Peter:
For a more clear understanding of stability I suggest you get a copy of Steve Killing's excellent book YACHT DESIGN EXPLAINED.


----------



## Alden68 (Mar 21, 2007)

CapnBilll said:


> which means that as the boat heels the volume of displaced water increases


That would only be the case if the boat somehow started to weigh more. It can't displace anymore water than its own weight. An asymetrical hull will change the trim of the boat as it heels which is why many boats round up rather quickly but it cannot displace any more water then when it was sitting at the dock.


----------



## bobperry (Apr 29, 2011)

Alden:
Exactly.


----------



## CapnBilll (Sep 9, 2006)

Let me add the disclaimers bobperry did, a lot depends on how flaired the hull, what ballast ratio, ratio of length to width, to how deep keel, weight of rigging, and sails, and mast, if sails are wet, and general design of boat. That is why even simular sailboats have very different stability numbers, and capsize ratios. More stable boats are often slower boats, and have deep keels that are bad for shallow water. You have to decide what you are going to use the boat for, and buy the best one for that application.


----------



## CapnBilll (Sep 9, 2006)

Alden68 said:


> That would only be the case if the boat somehow started to weigh more. It can't displace anymore water than its own weight. An asymetrical hull will change the trim of the boat as it heels which is why many boats round up rather quickly but it cannot displace any more water then when it was sitting at the dock.


Good point, perhaps a better way of stating it is, the assymetrical shape of the displaced water changes the center of buoyancy relative to the center of gravity.


----------



## reed1v (Apr 24, 2010)

Also depends on sea conditions and momentum of heeling. The c22 can quickly turtle in sudden squalls and steep chops. Hope you can swim.


----------



## bobperry (Apr 29, 2011)

Bill:
I'm not sure that I would say "more stable boats are often slower boats". Having a fast boat depends upon good stability so you can carry more sail longer. For today's extreme monohulls canting keels are used to improve stability.

I know exactly what you are saying. But I don;t think I would say it that way. You need more caveats.


----------



## PCP (Dec 1, 2004)

CapnBilll said:


> .. That is why even simular sailboats have very different stability numbers, and capsize ratios. More stable boats are often slower boats, and have deep keels that are bad for shallow water.


Yes, modern performance really fast boats with deep draft are definitively bad for shallow waters and would have lousy capsize ratios because they have normally a moderate to big beam and are light, however they are generally more stiff boats, boats with a big stability a good AVS and a big righting moment at 90º of heel. They needed to be very stiff to carry a lot of sail.

The reason the capsize ratio is bad it is because that capsizing ratio formula is completely meaningless in what regards modern boats with deep draft and a bulbed keel simply because it does not take into consideration the draft and all the weight in a bulb and that affects greatly the boat CG.

The capsize ratio will be bad but the stability curve of a racing boat like a Farr 400 or a Pogo 40 will be very good when compared with the one from a good old sailing boat.

Regards

Paulo


----------



## nolatom (Jun 29, 2005)

bobperry said:


> Bill:
> I'm not sure that I would say "more stable boats are often slower boats". Having a fast boat depends upon good stability so you can carry more sail longer. For today's extreme monohulls canting keels are used to improve stability.
> 
> I know exactly what you are saying. But I don;t think I would say it that way. You need more caveats.


I agree. I won't sail on a boat with less than six or seven caveats, they're just too tender ;-)


----------



## ChristinaM (Aug 18, 2011)

bobperry said:


> Bill:
> I'm not sure that I would say "more stable boats are often slower boats". Having a fast boat depends upon good stability so you can carry more sail longer. For today's extreme monohulls canting keels are used to improve stability.
> 
> I know exactly what you are saying. But I don;t think I would say it that way. You need more caveats.


There's initial stability required to start the boat heeling and for the first 30-ish degrees then there's absolute stability as in how far can she heel before going turtle. The two don't necessarily happen in the same boat.

Carrying a lot of sail relies on high initial stability. On a stability curve, this is the slope of the curve near 0 degrees.

Not inverting relies on high absolute stability, this is related to the angle of vanishing stability (where the curve crosses the horizontal axis) and the area under the positive area of the curve.

Check out Contessa vs Grimalkin stability curces (I don't have enough posts to post images yet). Both the Contessa and the Grimalkin have the same initial stability up to about 15 degrees but the Contessa has much higher absolute stability. It'd be very difficult to invert the Contessa and she wouldn't stay upside down.

A wide, flat modern design has high initial stability due to the width of the hull (hard to push it down into the water) but once you get it heeled significantly, there isn't much more force required to tip it to 90 or 180 degrees.


----------



## Ninefingers (Oct 15, 2009)

Alden68 said:


> That would only be the case if the boat somehow started to weigh more. It can't displace anymore water than its own weight. An asymetrical hull will change the trim of the boat as it heels which is why many boats round up rather quickly but it cannot displace any more water then when it was sitting at the dock.


I would have thought there would be some downward force created by the wind when heeled, but I guess it's just pivoting on an axis.

Here's a dumb question, which I am proud to ask, but I can't get any dumber; There was a video posted here of a canting mast sailboat. Would the displacement change as the wind increased on that boat?


----------



## peterchech (Sep 2, 2011)

bobperry said:


> Peter:
> For a more clear understanding of stability I suggest you get a copy of Steve Killing's excellent book YACHT DESIGN EXPLAINED.


http://www.amazon.com/Yacht-Design-Explained-Principles-Practice/dp/039304646X/ref=sr_1_1?ie=UTF8&qid=1323983800&sr=8-1

$270... $90 used... uke maybe _next_ christmas I'll treat myself lol...


----------



## peterchech (Sep 2, 2011)

Ninefingers said:


> I would have thought there would be some downward force created by the wind when heeled, but I guess it's just pivoting on an axis.
> 
> Here's a dumb question, which I am proud to ask, but I can't get any dumber; There was a video posted here of a canting mast sailboat. Would the displacement change as the wind increased on that boat?


No such thing as a dumb question IMHO.

The displacement of a boat is simply how many pounds of water its hull displaces when afloat. It is basically the overall weight of the boat as it sits. Salt water weighs around 64 lbs per cubic foot, so a boat that weighs 640 pounds must displace 10 cubic feet of water below the waterline in order to float. The weight of a boat does not change because it is heeled, it still must displace the same amount of water. (Always a caveat... some/most sail plans create some slight amount of downward force, and some boats employ "lifting sails" like a crab claw which can contribute some slight amount of lift, but simply heeling a boat does not change its displacement at all... unless ur in a C-22 and the crew spills out!!!  )


----------



## PCP (Dec 1, 2004)

ChristinaM said:


> *There's initial stability required to start the boat heeling and for the first 30-ish degrees then there's absolute stability as in how far can she heel before going turtle. The two don't necessarily happen in the same boat.*
> 
> Carrying a lot of sail relies on high initial stability. On a stability curve, this is the slope of the curve near 0 degrees.
> 
> ...


Christina,

Any boat has form stability and at very small hell angles that is what is responsible for almost all RM. Any monohull cruising boat relies also on ballast to lower the CG and the contribution of the ballast to create RM (if I may talk in a very simplified way) increases when the boat heels and at very great angles of heel the ballast is what counts more for creating RM.

A beamy boat has more form stability and a narrow boat has less, meaning that at heeling angles used to generate sail power a beamy boat relies more on form stability than on the effect of the ballast if compared with a narrow that boat relies less than the beamy boat on form stability and more in ballast.

But inferring from there that a beamy boat *" once you get it heeled significantly, there isn't much more force required to tip it to 90 ... degrees"* is not correct.

Modern boats, even very beamy ones have a bulb at the end of a significant draft. That bulb is calculated to give to the boat a good reserve stability and a good or at least reasonable AVS.

I will post a stability curve of a Pogo 40, a GZ curve in m and also a GZ stability curve of a Vaillant 40 and a Sabre 402, both in ft. I will post also the Contessa 32 GZ stability curve (in ft).

The Pogo 40 is a *VERY* beamy boat, with about 12m lenght for a 4.5m beam but you can see that the max rigt moment of the Pogo will be at about 75º of heel (and I would call that a significant heel) and that the Pogo max GZ is 58% bigger than the one from the Contessa. We can see also that even at 90º of heel the Pogo GZ is 28% bigger than the one from the Contessa. of course the Contessa is a smaller boat and even if we are talking about arms, it will make some difference.



















I am not saying that the Contessa is not a great boat with a very good stability, everybody knows that it is, just trying to show to you that the naval architects, particularly the ones that design modern boats know what they are doing and don't design unsafe boats.

It is also common knowledge that the Vaillant 40 is a great boat with a very good stability. You can see that it's stability curve is very different from the Contessa one, in fact it has more to do with the stability curves of modern boats than with old type curves like the one from the Contessa, but that will not make it less seaworthy. If the Vaillant had more ballast, the AVS would be superior and it would have less inverted stability but that would make it unnecessarily heavy and a slower and worse sailing boat.










Of course static stability is important and all boats should have a good reserve stability, a stability enough for raising them from any severe knock down, but static stability is only half the story. In what regards capsizes dynamic stability is at least as important as static stability

Regards

Paulo


----------



## bobperry (Apr 29, 2011)

Peter:
I agree. There is no such thing as a dumb question.

PCP:
Nice graphs. I wish I had those when I designed the Valiant 40. It might have made it a more succesful boat. ( mild snicker)

No, don't say that Bob. You are inches away from getting kicked off this site now.


----------



## Dean101 (Apr 26, 2011)

I'm not going to pretend that I understand more than about a quarter of what is being discussed in this thread. With that said, does the hull shape play a significant role in evaluating the stability of any given boat or is it rather minor in the scheme of things? To name an example, I've read that Cape Dory's are initially tender and in the same evaluation are considered to be very seaworthy vessels. I'm assuming that the initial tenderness is because they are described as relatively narrow but is their ultimate stability (whatever it actually is) a result of their hull shape, draft of the ballast, or possibly a combination of the two?

After looking at pictures of these long keels with a bulb on the end, it looks like it would take an act of Congress to invert them. But to my untrained eye, any type of keel that puts the weight of the ballast farther from the pivoting point would be increasingly hard to invert. Isn't that the purpose of having a swing type keel like the OP has? To place some weight deeper as well as limiting leeward movement while upwind sailing? 

Of course, I'm assuming that most swing keels have some proportionate weight to them. For all I know I may have just provided the chuckle of the day! I'l try to remember that you're all laughing with me, not at me.:laugher


----------



## bobperry (Apr 29, 2011)

Dean: 
I am not laughing at you at all. We all struggle ( at least I do) with the effort to reconcile
numbers on a graph to exactly how boats behave.

So, sit there, scratching your head trying to figure this all out and take some comfort in the fact that I have scratched a sore spot ( not a bald spot thank God) in my head trying to figure out the same stuff.

It's a good thing that we all can discuss this thing on a web site like this.


----------



## Alden68 (Mar 21, 2007)

Dean:

Don't worry...you have it figured out a lot more rationally than some people. You are absolutely right the Cape dory is a relatively narrow design shared by many of its era and philosophy. Initially tender because of limited form stability (the hull), but you hear all the time "she hardens up around 20 degrees". That is because dynamic stability, the keel, builds leverage as the boat heels and the limited resistance to heeling from the narrow hull shape is replaced by the righting moment (RM) of the keel. At low angles of heel the keel is simply hanging there, full of potential but doing very little. Wow, I just described myself. 

At larger angles of heel, form and dynamic stability work together to keep the boat upright with form stability giving up the ghost well before the keel; usually around 90 degrees. As a very, very blanket general statement most keel boats have an AVS (angle of vanishing stability) greater than 110 degrees. Think about that. 45 degrees would scare the Christmas right out of you. 110 is 20 degrees past parallel!!!! In fact wind alone cannot push a well designed keel boat anywhere near its AVS. You need wave energy to do that. 

If you look at the graphs above, the area above the line (0) represents the total amount of energy required to push the boat past its AVS. The area below the line represents the amount of energy required to roll the boat back onto its feet. The boats that we mortals sail, unless we are sailing a catamaran, should have a much smaller area below the line than above. So, when that rouge wave does roll your boat off of Cape Horn you need a relatively small amount of energy (the next wave) to roll her back over.

Modern beamy race boats will require more energy to roll back over than a standard production keel boat because not only does that form stability from the wide beam work very well upside down, the wide flat decks "suck" themselves against the water due to surface tension and other factors. In fact, in the ultimate case of the negative affects of beam, a catamaran is more stable inverted than right side up!!!


----------



## PCP (Dec 1, 2004)

Alden68 said:


> ...
> 
> If you look at the graphs above, the area above the line (0) represents the total amount of energy required to push the boat past its AVS. The area below the line represents the amount of energy required to roll the boat back onto its feet. The boats that we mortals sail, unless we are sailing a catamaran, should have a much smaller area below the line than above. So, when that rouge wave does roll your boat off of Cape Horn you need a relatively small amount of energy (the next wave) to roll her back over.
> 
> Modern beamy race boats will require more energy to roll back over than a standard production keel boat because not only does that form stability from the wide beam work very well upside down, the wide flat decks "suck" themselves against the water due to surface tension and other factors. In fact, in the ultimate case of the negative affects of beam, a catamaran is more stable inverted than right side up!!!


Alden, it's close but with an important difference. The area that represents the energy required to roll the boat is not the one that is behind those curves (GZ = lenght arm curves) but the one that is behind the righting moment curves (RM) and they would give very different results.

The curves would have exactly the same AVS but the one from Pogo that looks to have much more stability than the Vailant (GZ curve) would be now not very different. That's because for obtaining a RM curve you have to multiply the GZ (arm) by the boat displacement and the Vaillant weights about the double

Regarding the inverted stability, yes, a boat that has more form stability upright will have also more form stability inverted but you are forgetting that big bulb up high in the air.

Take a look how this hugely beamy racing Open60 is capable of re-righting itself without outside help:






And if you think that with a mast it would be more dificult, well, as strange as it seems, it is more easy

Regarding those curves what really is important in what regards inverted stability is the proportion between the area under the positive part of the curve and the negative part (inverted stability). A sailboat is only capsized by breaking waves and that relation, if it is for example the 3 to 1 means that it is only needed a wave 3 times smaller than the one that has capsized the boat to put it again the right way up. That should not be difficult to get and should happen in less than 2 minutes.

Regards

Paulo


----------



## Alden68 (Mar 21, 2007)

Come on Paulo that is trickery to try and make a point....that boat has a canting keel!

Without the keel mechanism that open 60 would have sat upside down in that harbor for the rest of time!

Canting keels throw the inverted portion of the stability curve out the window. They create their own kinetic energy! Something very difficult for a Cape Dory to accomplish don't you think?


----------



## Dean101 (Apr 26, 2011)

PCP, that was an interesting video. I tried searching youtube for videos of similar tests on more conventional boats but came up empty. I must say though that it righted itself much slower than I would have thought given the fact that it had no mast, rigging and sails, or loaded weight from electronics, provisions, water, etc. 

I did watch a video where they loaded a boat for normal use, including crash dummies, and rolled it over. Even with all the unsecured provisions now piled up on the overhead, which I'm sure added to the boats inverted ballast, I could tell by the load on the crane's nylon rigging that the boat was eager to right itself. It didn't have the kind of beam that the boat in your video had either. 

I also noted that the boat in your video was of a much lighter displacement than the one I watched. The cruising boat just seemed to pivot around an axis as it rolled with very little upwards movement. Your test boat seemed to have to lift well over half the beam of the boat out of the water before it passed the 90 degree position. That would be a definite help in keeping water out of the cabin.

I'm beginning to think that beam and the resistance it has to heeling might be a double-edged sword.


----------



## CapnBilll (Sep 9, 2006)

Dean101 said:


> I'm beginning to think that beam and the resistance it has to heeling might be a double-edged sword.


I'm thinking you might be right.

Let's look at the "ultimate safe hull shape". A sphere like a giant hamster ball with a large weight 1/2 of it's displacement bolted to the bottom...Initial stability = 0, ultimate stability = 100. Such a boat would not be very comfortable uke, (or sailable), as it would roll constantly, BUT...if inverted it would right itself instantly with no external force. Kinda like a submarine hull at the surface.

Go to the other extreme and you have a catamaran, high initial stability that drops rapidly with heel, goes to zero at 80-90 degrees.

somewhere in between these extremes are all monohull sailboats.

Blue water cruisers tend toward one end with narrow hulls, and deep heavily ballasted keels for stability, and racing boats tend to the other end with wide hulls and shallow, less ballasted keels so they can carry more sail with less overall weight.

In life everything is a compromise.


----------



## PCP (Dec 1, 2004)

Dean101 said:


> PCP, that was an interesting video. I tried searching youtube for videos of similar tests on more conventional boats but came up empty. I must say though that it righted itself much slower than I would have thought given the fact that it had no mast, rigging and sails, or loaded weight from electronics, provisions, water, etc.
> ...


You don't find it because there are any. Production boats are not subjected to this experience and if they were none of them would be able to right itself up in flat water, neither the contessa 32. They need waves to be able to right itself up.

This is an Open 60 solo racing boat and they have the more demanding exigences in safety of all sailingboats. They have to pass successively this prof. If you google video rollover Open 60 you are going to see several videos. They manage to do that canting the keel and changing the water ballast.

If they have not changed the rules to make them even safer, they have to had at least an AVS of 125º on the least favorable configuration that is, the keel canting to the wrong side and the wrong water ballast full, I mean that, more the capability to righting itself alone. That's huge and the requirements are so tough that older Open 60's cannot comply.

In what regards modern production I would say that 95% of the boats has an AVS between 105º and 135º being the more common between 115º and 125º.

The AVS is not the only important factor. As important is the force that the boat is making to right itself up at 90º and also very important, as I had already said is this:

*"Regarding those curves what really is important in what regards inverted stability is the proportion between the area under the positive part of the curve and the negative part (inverted stability). A sailboat is only capsized by breaking waves and that relation, if it is for example the 3 to 1 means that it is only needed a wave 3 times smaller than the one that has capsized the boat to put it again the right way up. That should not be difficult to get and should happen in less than 2 minutes".*

The European community RCD introduced minimum requirements on boat stability that includes a minimum AVS for each category and as practically all boats over 30ft are Class 1 (offshore) that means that you can trust in a minimum stability that is in accordance with the numbers I had given.

Regarding old boats, many have good stability and good AVS but some, especially old cruiser-racers can have really poor AVS, some with less than 100º. Some old boats can also have an acceptable or good AVS but can have considerable less righting moment at 90º comparing with a modern boat.

Generally weight for weight, modern boats have an overall better stability meaning that area behind the RM curve that represents the needed area to capsize them is bigger, but of course older designed boats tend also to be more heavy and that can compensate in stability the better GZ curve of modern designed sailboats.

Regards

Paulo


----------



## PCP (Dec 1, 2004)

CapnBilll said:


> ...
> somewhere in between these extremes are all monohull sailboats.
> 
> Blue water cruisers tend toward one end with narrow hulls, and deep heavily ballasted keels for stability, and racing boats tend to the other end with wide hulls and shallow, less ballasted keels so they can carry more sail with less overall weight.
> ...


Well, narrow hulls today are a rarity even in modern blue water boats and what was some 20 years ago considerate beamy is now a moderate beam. And there are many good bluewater cruisers with a beamy hull, boats that have taken inspiration on those solo racers that are designed to be very stable and easy sailed for a solo sailor.

Some examples of well known modern bluewater boats with a moderate beam that 20 years ago would be considered beamy:

The new Halberg-Rassy 412: Hull lenght 12.61m, Beam 4.11m

The X yacht XC 42 : Hull lenght 12.81m, Beam 4.11m

The Oyster 46: Hull lenght 13.94, Beam 4.41m

Some examples of well known modern bluewater beamy boats:

Cigale 14 : Hull lenght 15.99m, Beam 4.79m

RM 1350 : Hull lenght 13.46m, Beam 4.50m

Pogo 50 : LOA 15.25, Beam 5.16m

There are also some other brands like passport that continue to make what has called medium beamed boats and that I would call by today parameters narrow cruising boats but I don't think that it is correct to say that *" Blue water cruisers tend toward ... narrow hulls"*. It is quite the opposite, today those are a minority on the actual trend.

You say also that *"racing boats tend to the other end with wide hulls and shallow, less ballasted keels"* and there seems to have some confusion here. I guess you did not wanted to say shallow, because it is just the opposite, all racing boats have deep keels (substantially more deep than cruising boats) and if the handicap rules don't penalize them too much, they all have lead bulbs.

Racing offshore boats have normally a high B/D ratio and the ballast effect is potentiated by their big draft and bulbed keels. I don't think it make sense to say that they tend to be beamy. There are many types of offshore racing boats, all of them have a huge stability and only on the ones that are conceived to go solo on downwind races you are going to find a clear trend on beamy boats (that have also a good B/D ratio if compared with cruising boats). The Pogo stability curve that I have posted is typical of one of those boats and you can see that the boat has a good reserve stability and a good AVS.

Even regarding solo boats, or boats that are used to solo race in varied wind conditions you are going to see that they are not beamy boats, if compared with modern cruisers. For Instance the A 35 or the Benetau Figaro.

In what regards offshore racing with a crew the boats are less beamy than modern cruisers of the same size, for instance the mew J 111, the Santa Cruz 37, the Farr 400 ot the ker designed racing boats have all a moderate beam and some of those boats come near to 50% of B/D and has I said that ballast is potentiated by a deep fin keel with almost all ballast deep down in a bulb.

Racing boats are very stiff boats with a huge stability. The only reason for them to be other way were handicap rules that have originated in the past some pretty bad boats. Not anymore.

Regards

Paulo


----------



## peterchech (Sep 2, 2011)

As discussed on another thread, this is all great theory but the truth is no matter how much inverted stability your boat has, if the hatches/lockers aren't shut and waterproof then you will ship enough water in a knockdown/capsize that the stability curve will be thrown out the window. Google J-24 sinking and you will find many instances in which unsecured cockpit lockers resulted in sinkings after a mere knockdown for just this reason.

I understand that modern offshore boats, esp single handers, are often modified (or built custom) with a tupperware philosophy. They are completely sealed when the hatches are shut. Positive flotation is also a good idea, used by the serious offshore folks when possible.


----------



## PCP (Dec 1, 2004)

peterchech said:


> As discussed on another thread, this is all great theory but the truth is no matter how much inverted stability your boat has, if the hatches/lockers aren't shut and waterproof then you will ship enough water in a knockdown/capsize that the stability curve will be thrown out the window. Google J-24 sinking and you will find many instances in which unsecured cockpit lockers resulted in sinkings after a mere knockdown for just this reason.
> 
> I understand that modern offshore boats, esp single handers, are often modified (or built custom) with a tupperware philosophy. They are completely sealed when the hatches are shut. Positive flotation is also a good idea, used by the serious offshore folks when possible.


You are right. Another important angle that was not mentioned and that is regulated regarding a minimum by the RCD is the down-flooding angle that ideally should be bigger than the AVS angle. Normally beamy boats if well designed have better down-flooding angles or at least is more easy for a designer to obtain a very good one on a beamy boat.

Some stability curves show the down-flooding angle.

Regards

Paulo

Edit- I saw those photos and I don't know what happened but on a light boat like the J24 the weight of the crew has a lot of importance. If they keep making weight on the wrong side of the boat probably it is not going to right itself up.

You can see this J 24 that with the crew on the wrong place (I don't understand why the guys didn't crawl to the right side of the boat) is able to right itself up. The only guy that is doing something is the skipper that ends up in a funny position, again, with nobody helping. What a crew


----------



## Alden68 (Mar 21, 2007)

They are absolutely theoretical as you have pointed out. No graph in the world matters when your copy of Chapmans flies off the shelf and stoves in your head. But they are excellent comparison tools for people looking to take their boats places where they could encounter conditions that will push the design of the boat. 

Darwinism aside you just have to assume that no one is going to round the horn with the companionway and main hatch open! A sunny day racing a J boat is a different story.

Paulo:

That is amazing that the open 60 has to have an AVS of 125 with the keel on the wrong side and the water ballast on the wrong side. That is amazing!


----------



## PCP (Dec 1, 2004)

Alden68 said:


> ..
> 
> That is amazing that the open 60 has to have an AVS of 125 with the keel on the wrong side and the water ballast on the wrong side. That is amazing!


Yes they are amazing boats but sometimes they capsize...when they lose the bulb That's a problem that they did not have solved yet and it has also to do with the speed: It is very different to hit a whale at 7k or at 20K (and at 7K the whale probably will have time to escape).

Anyway, just to give you an idea of the stability of those boats, last Vendee Globe one of the guys lost the keel on a collision near Brasil, didn't give up and brought the boat home and to the finish line on the North of France sailing without a keel, doing at times 10K, using only water ballast tanks, and remember he was alone.

Regards

Paulo


----------



## peterchech (Sep 2, 2011)

PCP said:


> Yes they are amazing boats but sometimes they capsize...when they lose the bulb That's a problem that they did not have solved yet and it has also to do with the speed: It is very different to hit a whale at 7k or at 20K (and at 7K the whale probably will have time to escape).
> 
> Anyway, just to give you an idea of the stability of those boats, last Vendee Globe one of the guys lost the keel on a collision near Brasil, didn't give up and brought the boat home and to the finish line on the North of France sailing without a keel, doing at times 10K, using only water ballast tanks, and remember he was alone.
> 
> ...


wow... what was that guy's name I need to google his picture and put it in the wikipedia definition of "balls" 

The whale didn't escape when hit at 20 knots?

have whale carcasses actually been found after collisions?


----------



## PCP (Dec 1, 2004)

Yes, that was an incredible feat of seamanship. They try to convince him to give up but Marc tell them it would not be different to sail a dinghy and that he was good at that.

Not only he made 1000nm without a keel as it made them as fast as he could given the circumstances and managed to keep his 3th place. A hell of a sailor among other legendary sailors that you can find at the Vendee.

Marc Guillemot finishes third in the Vende Globe - Yachts and Yachting Online

Regards

Paulo


----------



## Barquito (Dec 5, 2007)

> No graph in the world matters when your copy of Chapmans flies off the shelf and stoves in your head.


That is the most rational description of seaworthiness I have seen.:laugher


----------



## [email protected] (Dec 15, 2011)

I've been near vertical in the cockpit in our C-22 and it righted itself. I've also seen one put the tip of the mast in the water and come back up, if that helps. When the air kicks up, we put spring clips (like on a dog leash) on the cockpit hatches to make sure they stay closed, and put the companionway boards in and close the main hatch, in order to minimize taking water into the cabin.
If a swing keel C-22 goes turtle, most likely the 550 lb keel will come down very hard and fast causing serious damage to the boat. The locking device is a friction lock consisting of a large bolt tightened against the side of the keel. It might slow down the drop, but I doubt that it would prevent the keel from hitting the hull.
Most C-22's do not have positive floatation, but for some period of time it was an option because our 1975 model C-22 does have positive foam floatation. It is in the storage compartment under the v-berth (not the anchor locker), under the cockpit floor, and under the starboard bunk/storage area aft of the cabin.
Virtually all of the C-22's that are seriously raced do not have the floatation, and those that did took as much out as they could to reduce weight.


----------



## Dean101 (Apr 26, 2011)

Ahhhh.... Compromises, compromises....

I haven't yet seen a list of those that work for everyone.


----------

