Alubat , Ovni

[aitchem]

Hi all,
I would like some opinions of the Alubat Ovni Yachts.
These have swing keels, and I have been told their stability was questioned some time ago, in the yachting press, I missed it all.
They are quite nice looking and able to take to the ground.
The mainsail looks challenged sizewise.
How does a deep small keel sail as opposed to the conventional cruiser long keel.

thnks
aitch

[D'ARTOIS]

Alubat Ovni's are already for a long time on the scene. I don't think, that if they were that bad, they would still be around. No, I don't think they are that bad.
They are far from beautiful - my personal opinion, but hey have their admirers.
If you want toknow about stability,or in the case you have doubts, ask the yard to send you the necessary stability curves, necessary to fulfil the CE requirements.

According to the sailing capacities, the centreboard keel is in performance slightly inferior to the small deep keel boat or to the conventional long keeler.
Because of the higher COG the boat needs more of the internal ballast and has therefore different characteristics as being a bit cruel when the centrboard is raised.

Keep in mind that the French are quite ingenious when it comes to the production of sailing yachts although they cannot compete against the Dutch quality, the price of them might convince many sailors to choose for the French boat rather than for the Dutch.

I have been contacted long time ago by a member from Spain who was equally interested in aluminium boats and who came forward with another design from STRONGALL, also a chined hull, however looking very sturdy.

Surfing the French sites might give you more info.

[Vega]

I am not as optimistic as D'Artois about the stability numbers of those boats.
In my opinion they are alright to cruise in coastal waters but with this kind of boat, anything smaller than 45' is not adequate to oceangoing.

I have already done what D'Artois suggests, I have asked information to the manufacturers of two French 40' "deriveurs". Not from the OVNI, because as D'Artois has pointed out, they are ugly, but from two similar boats (nice boats D'Artois), the Alliage 41 and the Allures 40.

The first one is an expensive boat, kind of top of the class of French Aluminium boats (with "Garcia" that don't make boats smaller than 46'), the other one is a recent French hit in the aluminium market, and it is a nice boat with a very attractive price.

Even if I demand specifically to be informed with stability data, only the more expensive boat builder have sent what I have asked. From Allures I have received a lot of information, but nothing about stability.

These boats have all the Ballast inside the boat.
The Allures 40 has a displacement of 8.8T with 3.8T of ballast.
The Alliage 41 has a displacement of 9.9 and 3.6T of Ballast.
The Ovni 385 has a displacement of 8.5T and 2.9T of Ballast.

Those boats have a similar hull shape, and form stability should not be very different among them.

The Alliage 41 has an AVS of 114.6º and a Stix number of only 32,41. From those three, this is the one that has , with all probability, the best numbers regarding stability. These are very poor numbers for an oceangoing boat.

Concerning stability, these boats are very far away from the Dutch Atlantic 42 or from the British Southerlys (boats with a lifting keel). These boats have a substantial part of their ballast outside the boat, and deep, when the keel is down. Both have an AVS exceeding 135º, and for instance, the Southerly 115 (37’) has a substantial Stix number of 54,6.

The Southerly 115 has a displacement of 7.8T, a ballast of 3.5 T, and from that ballast 1.2T is on the keel. The boat has a draught of 2.5m. keel down.

Comparing RLs, this boat has around 0.9 GZ(m) and the Alliage less than 0.6.

I think that “Garcia” has taken the right move, not doing those babies smaller then 46’, at least if they want to advertise them as passage makers, as Ovni and Alliage do.

[lazeyjack]

Read the posts with interest
What these boats do have is stability at anchor, two chines beat the heck out of round bilges, It is not very pleasent to sit in the roly poly anchorages of the South Pacific, often there is no choice , so I was looking at one for myself
As a long time builder in al al(aluminium alloy) see gallery photos, I do not particulary find them ugly so much as functional and manly
If you want one, send me a plan, I will price it and guarantee workmanship of the highest standard, having built under Lloyds etc

[Vega]

The Allures 40 and the Alliage 41 are round bilges boats.
Only the OVNIs have chines.

http://www.alubat.com/

http://www.allures-yachting.com/site_uk/index3.htm

http://www.alliage-yachts.com/GB/home_chantier.htm

[aitchem]

Thanks for the numbers, I am not convinced about swing keels either.

The Southerly 135 would be ideal if it wasn't plastic.
The Ovni 455cc would be desirable with a proper keel.
The Alliage 48cc looks very nice, never heard of them, but looks expensive.

I'll just keep looking.

[Milan]

There are more factors to consider talking about seaworthiness then just stability angles. "Deriveurs" are actually very popular type in France for ocean voyaging. Lots of these boats are built over the years, some by well-known yards, and others almost unknown. Many of them sailed far and wide, oftenly in high latitudes. Their ultimate stability is lower but they heave some other characteristics that compensate for that. In heavy weather, boat with all inside ballast and centerboard or daggerboard, lifts the board completely out of the water. That moves center of lateral plan aft, making running very easy and eliminates danger from broaching. Also, if hit by the wave from the side, boat just skids to a side and tends to turn away from the wave. in same conditions boat with a deep keel sort of - trips over the keel, heeling much more and maybe even capsizeing.

Aesthetics - well, beauty is in the eye of beholder. Personally, I quite like that form follows the function looks of Ovni's.

Few links - Jimmy Cornell's voyages on the Ovni 43, and META built boat who visited Antarctic among the other places…

http://www.noonsite.com/aventura/aventura3.html
http://www.metapassion.fr.fm/
http://www.justmueller.com/boats/
http://www.dujardin-icofrance.com/
http://caroffduflos.free.fr/

[D'ARTOIS]

Milan, is it possible that you contact me? I have to ask you something.

[lazeyjack]

Originally Posted by aitchem

Thanks for the numbers, I am not convinced about swing keels either.

The Southerly 135 would be ideal if it wasn't plastic.
The Ovni 455cc would be desirable with a proper keel.
The Alliage 48cc looks very nice, never heard of them, but looks expensive.

I'll just keep looking.

Can i ask why you dont have one drawn up exactly to your requirements?

[Vega]

Originally Posted by aitchem

Thanks for the numbers, I am not convinced about swing keels either.

Don't get me wrong. I only don't like swing keels that have no ballast.
As Milan pointed out a swing keel or a retractable one will have other advantages besides reducing draft.
There are several aluminium boats that have these keels and have also good initial and final stability.
Some examples:

http://www.atlanticyachts.nl/
http://www.berckemeyer-yacht.de/yachts/bristol_39.html#
http://www.berckemeyer-yacht.de/yachts/cape_45.html
In Dick Zaal site, look under Design/ studies for “Adrenaline” and under Design/aluminium for Coronet 41’ and Coronet 44.
http://www.dickzaalyachtdesign.nl/

Originally Posted by Milan

There are more factors to consider talking about seaworthiness then just stability angles. Their ultimate stability is lower but they heave some other characteristics that compensate for that. In heavy weather, boat with all inside ballast and centerboard or daggerboard, lifts the board completely out of the water. That moves center of lateral plan aft, making running very easy and eliminates danger from broaching. Also, if hit by the wave from the side, boat just skids to a side and tends to turn away m the wave. in same conditions boat with a deep keel sort of - trips over the keel, heeling much more and maybe even capsizeing.

Of course you are right, but it is not only final stability that is poor. Initial stability is also poor. These boats only sail well following the wind. They lack initial stability to carry enough sail against the wind.
They have also a strong negative stability ( A41': more than 0.3 GZ(m)) and when capsized they will stay capsized for a long time (beamy boat with a high center of gravity) . As any small boat can be capsized easily, giving the right conditions, this type of boat (Swing unballasted keel) will not fulfill my criteria for a passage maker.

[Milan]

D'artois, you are of course very welcome, I already sent a mail to you.

Vega,

Initial stability is mainly form stability. At least for the first 15 - 20 degrees of heel. The weight of the keel begins really to work after that, with higher heel angles. As the beam is major form stability factor and "deriveurs" have a lot of it. they shouldn't have trouble caring sail in moderate conditions. In the stronger winds they have to reef earlier then deep keeled boats but there is a room for improvement of their performances for more ambitious. Water ballast tanks in their sides would improve sail caring a lot. They would also benefit a lot from the modern sail plan with a fully battened, highly roached main sail, which would provide a lot of sail area with a relatively low center of effort.

As for chances to turn upright after capsize, negative stability depends a lot from the shape of the deck and everything above. Strongly built but light, (aluminum), watertight deckhouse could considerably improve righting chances, but main thing for these boats is that because of described skid factor and breach - proefness they don't capsize.

Being as they are, they seem to have proven their practicality and safety for long distance voyaging with reasonable performances. Meffre's voyages with photos among the ice blocks seems pretty convincing to me.

Lifting ballasted keels seems to offer a lot, but I'm worried about price, complexities and long term potential maintenance headaches which huge lamps of lead attached to a thin, movable plates, could provide. I'm curios what happen when such keel hits a rock at speed. In contrast with that, all ballast inside and daggerboard looks so simple and cheap, practically foolproof. Combined with a thick hull shell as in Metapassion they give a peace of mind and confidence to visit some rough places.

In the end, I must say I'm not some kind of deriveurs - crusader who fanatically propagate his favorite boat. I like many different kinds of boats, trying to keep an open mind. But in general, I do like to sail fast, I prefer simplicity and have special soft spot for lean, narrow boats.

If I ever win a lottery, I would go for something like attached photos. Lottery wining chances being what they are, I'll continue, (slow), designing work on my fast, simple, leen, cheap, steel gaff schooner which I mentioned before.

Milan

[Vega]

Originally Posted by Milan

Initial stability is mainly form stability. At least for the first 15 - 20 degrees of heel. The weight of the keel begins really to work after that, with higher heel angles. As the beam is major form stability factor and "deriveurs" have a lot of it. they shouldn't have trouble caring sail in moderate conditions. In the stronger winds they have to reef earlier then deep keeled boats …

Milan

Initial stability of a boat is in direct connection with the sail area that a boat can carry.

Lets look at the initial stability (RM) of 3 different boats at 10º, 20º and 30º of heel. The boats, the Alliage 41, the Malo 41 and the Hanse 411, have aprox. the same LWL. The Malo 41 weighs aprox. the same as the Alliage 41 and the Hanse is 1.6T less heavy than the Alliage ( unfair for the Hanse).

Alliage: 10º -21KN ; 20º-39KN; 30º-50kn. Malo: 10º-28KN; 20º-49KN; 30º-69KN.
Hanse: 10º-28KN; 20º-48KN; 30º-60KN.

The standard sail (for sailing against the wind) for these boats are Alliage- 90m2, Hanse-92, Malo-99m2.

As you can see, the RM values of the Alliage are a lot lower than the values of the other two boats The Malo will out perform very clearly the Alliage and the Hanse (with better values and 1.6 tons less) will disappear rapidly in the horizon.

About final stability, Max RM (the total force needed to capsize the boat) is 69KN for the Alliage (not as bad as I had thought) against 95KN for the Malo. The Hanse has also a max. RM of 69KN.

I do not consider the Hanse 411 a passage maker, even if it has an AVS a lot better than the Alliage and will not (contrary to the Alliage) stay capsized for a long time. The Hanse is not advertised as a passagemaker,but the Alliage and the other French Deriveurs, with worse stability data are advertised as such.

Originally Posted by Milan

these boats ….. don't capsize.

Milan

You are kidding…right?

http://i19.photobucket.com/albums/b152/vega1954/ss.jpg

Originally Posted by Milan

Lifting ballasted keels seems to offer a lot, but I'm worried about price, complexities and long term potential maintenance headaches which huge lamps of lead attached to a thin, movable plates, could provide. I'm curios what happen when such keel hits a rock at speed. In contrast with that, all ballast inside and daggerboard looks so simple and cheap, practically foolproof. Combined with a thick hull shell as in Metapassion they give a peace of mind and confidence to visit some rough places.

…..I prefer simplicity and have special soft spot for lean, narrow boats.

Milan

Yes, I agree with you in all points. But ballasted swinging keels are also simple, don’t have problems when hitting the ground, and are used in Southerlies for more than 20 years without complaints. They are also used in the Atlantic (Dick Zaal) with excellent results regarding initial and final stability.

[danera]

I've sailed around 15k miles on a Ovni 43, from Antarctica to Alaska. Their AVS is low compared to more traditional designs but that doesn't necessarily stop them being suitable passagemakers. If you are biased against them and other deriveurs, then maybe it isn't worth having the debate, but for many people they make good, seaworthy cruising boats.

For me the offshore part of any voyage is by far the safest: far more boats are lost running aground than being capsized in storms. I would rather be on an Ovni that sails well, has a smallish, easily handled rig & strong hull construction. They don't have blistering performance, you have to be careful not to stall the flat centreplate by pinching, but downwind in the trades with the board up they are one of easiest (= least tiring) boats I've ever sailed on. And that's how most cruising sailors like it.

Ivan

[Vega]

Originally Posted by danera

If you are biased against them and other deriveurs, then maybe it isn't worth having the debate, but for many people they make good, seaworthy cruising boats.

For me the offshore part of any voyage is by far the safest: far more boats are lost running aground than being capsized in storms. I would rather be on an Ovni that sails well, has a smallish, easily handled rig & strong hull construction. They don't have blistering performance, you have to be careful not to stall the flat centreplate by pinching, but downwind in the trades with the board up they are one of easiest (= least tiring) boats I've ever sailed on. And that's how most cruising sailors like it.
Ivan

Why do you say I am biased? Nothing that you have said contradicts what I have said. I have even said that these boats are good cruising boats, for sailors for whom speed is not important.

I have said that these boats were good running with the wind and poor when going against the wind. I have explained why, analyzing and providing data that show the differences in stability (initial and final) between these boats and similar fixed keel boats.

Am I biased only because I don’t share with you the opinion that this kind of boat (when smaller than 45’) has all the conditions required by a Passage maker?

Am I biased when I express the opinion (shared by many) that any small boat can be capsized in a severe storm, and that therefore any small boat that is suited for passagemaking should have a self rightening ability in less than a minute?

It is known that for doing that a boat should have an AVS of at least 125º (some discussion about it, but the number is between 125 and 135).

Am I biased when I say that any small boat with an AVS between 100º and 115º (typical AVS of the French Deriveurs), should not (in my opinion) qualify as Passagemakers?

Originally Posted by danera

I've sailed around 15k miles on a Ovni 43, from Antarctica to Alaska. Their AVS is low compared to more traditional designs but that doesn't necessarily stop them being suitable passagemakers.

Ivan

I sail a Bavaria 36. A countryman that I know has recently toured around the world in one. An English friend has crossed the Atlantic in another several times.
These facts don’t make these boats (in my opinion) passagemakers.

Botom line about being biased about Deriveurs: I have already said that I like Southerlies and Atlantics very much. These are Deriveurs that have the same advantages of the French ones (at least Atlantic that is also an aluminium boat) and none of the disadvantages. Those have all the criteria to (in my opinion) be considered not only passagemakers but also sailing boats with good sailing performance in all points of sail.

[danera]

You stated that you don't 'like' unballasted swing keels which I interpreted as a bias against centreboards. I didn't mean it as a criticism, but I guess we have differing opinions on what a 'passagemaker' should be. As an aside, the only boat I've sailed on that had been capsized was an Ocean 60, all 30 tons of it in the mediterranean.

Regards,

Ivan