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Old 18-09-2009, 18:45   #1
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Anyone Ever Sail a Cat with an Aerorig?

Interesting system and wonder how they sail.
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Old 18-09-2009, 21:56   #2
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There's a Hirondale in our marina with an Aerorig. The owner has quite a bit of sailing experience as he circumnavigated in a Prout some years ago. It took him a while to learn the rig but now swears by it.
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Old 20-09-2009, 00:16   #3
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Interesting system and wonder how they sail.
like any other catamaran of same hull design, physics does not change, the problem sits in your head, once understood the principle that you are ALWAYS close hauled unless running, there is no more problem.

much easier handling of sails, no danger of jibbing when BOTH sails are up. more weight aloft and in the hull (bearing), more elasticity, hence a 5m boom swings quite a lot, but in gereral a much easier rig for a small crew. for speed adjustment freaks not so good as there is not much to adjust. had one for 9 years on my 47ft cat ;-)

If I'd choose easy sail handling today I'd might go for a bi-rig (one unstayed mast in each hull, no jib)
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Old 20-09-2009, 07:39   #4
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I wanted to see what this rig might look like and came accross this very interesting article which anyone interested in CATs might enjoy reading...but it did have a section on this type of rig...


Choosing the right offshore, live-aboard catamaran.


"A catamaran places huge loads on the hull. Much larger than is placed on a monohull because of the tremendous inherent stability. With a monohull, for instance, when a puff hits, the hull leans over relieving some of the loads. With a catamaran, all of the loads are not only transferred to the hull, they come as a shock load with an enormous initial impact.
Whatís great about the normal cat rig, is that you have a wide angle for the shrouds which translate much of the forces to the strongest part of the hull directly. Now you are sharing the loads on the cross beam and the hull.
With the aero-rig, everything is transferred to the area of the cross beam, and in a catamaran, you donít have the height between the bottom of the hull and deck as you do in a monohull to distribute the cantilever loads. Bottom line? A catamaran is a poor candidate for the Aero rig and as the size gets larger, the loads go up exponentially so this applies in spades.
Secondly, Iíve personally been witness to side by side comparisons and the Aero rig simply does not have the same performance or versatility as a conventional rig. Yes you can get most manufacturers to install it if you insistócheck to see if theyíll still offer the same structural warranty though?"
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Old 20-09-2009, 09:45   #5
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Originally Posted by capcook View Post
I wanted to see what this rig might look like and came accross this very interesting article which anyone interested in CATs might enjoy reading...but it did have a section on this type of rig...


Choosing the right offshore, live-aboard catamaran.


"A catamaran places huge loads on the hull. Much larger than is placed on a monohull because of the tremendous inherent stability. With a monohull, for instance, when a puff hits, the hull leans over relieving some of the loads. With a catamaran, all of the loads are not only transferred to the hull, they come as a shock load with an enormous initial impact.
Whatís great about the normal cat rig, is that you have a wide angle for the shrouds which translate much of the forces to the strongest part of the hull directly. Now you are sharing the loads on the cross beam and the hull.
With the aero-rig, everything is transferred to the area of the cross beam, and in a catamaran, you donít have the height between the bottom of the hull and deck as you do in a monohull to distribute the cantilever loads. Bottom line? A catamaran is a poor candidate for the Aero rig and as the size gets larger, the loads go up exponentially so this applies in spades.
Secondly, Iíve personally been witness to side by side comparisons and the Aero rig simply does not have the same performance or versatility as a conventional rig. Yes you can get most manufacturers to install it if you insistócheck to see if theyíll still offer the same structural warranty though?"

The writer of this article and the others there sells cats. Obviously not one with aero-rigs, even though that is not the correct name. Aero-rig was a UK company that folded after building numerous rigs that were way too heavy (expensive carbon). The correct name is probably a Ballestron rig.

The required mast "bury" can be anything you wish to design for, sure it's easier to do in a deep hull, but there are several cats with Ballestron rigs.

Performance wise, for the same size rig, they offer better performance on all points of sail, smallest advantage is hard on the wind, as you go towards a reach they improve the advantage. Off the wind you get no blanketing.

So the writer suggesting that these rigs are not versatile and don't perform doesn't know what he is talking about.

There was a side by side test done on a couple of smaller cats in the UK about 15 years ago, and as far as I remember, the Ballestron rig offered the same performance with about 30% less sail area.

Anyone have a copy of that aricle??

Alan
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Old 20-09-2009, 12:55   #6
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More intricate structurally thus probably more expensive to build. What the benefit?

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Old 20-09-2009, 14:02   #7
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More intricate structurally thus probably more expensive to build. What the benefit?

b.
The primary benefit is ease of sail handling. There is a Shuttleworth designed catamaran being built here locally that has an Aerorig.





John Shuttleworth AeroRig 52
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Old 20-09-2009, 16:49   #8
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Well, you still have the main sheet and the jib sheet? So where is this ease of handling? No kicker. ok, but most cats do not have kickers anyway. Not quite see this ease thing.

How do you control the mast? You cannot leave it free-wheelin', can you? How does the mast-control mechanism add to the ease of handling.

I like it as an idea, but can't see any benefits. Actually looks like much more prone to failure than the normal thing.

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Old 20-09-2009, 17:10   #9
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Well, you still have the main sheet and the jib sheet? So where is this ease of handling? No kicker. ok, but most cats do not have kickers anyway. Not quite see this ease thing.

How do you control the mast? You cannot leave it free-wheelin', can you? How does the mast-control mechanism add to the ease of handling.

I like it as an idea, but can't see any benefits. Actually looks like much more prone to failure than the normal thing.

b.

Here is the decriptive commentary of a gentleman who has sailed with the aerorig shorthanded during a circumnavigation with his wife and young kids. He's sailed with the rig for approx 30,000 naut miles and describes the rigs function, and his experience with it, as follows:

Quote:
The mast is totally unstayed and is mounted in two bearings - one in the bottom of the hull and one in the deck. These allow the mast - and therefore the whole rig -- to rotate freely. The jib is completely self - tacking on a traveller mounted on the mast.

As long as more sail is set behind the mast than in front of it, the Aerorig will weathercock into wind if left to its own devices. The whole rig can therefore be controlled and the sail angle set by restricting the angle of rotation using a single mainsheet.

This is amazingly easy to manage and trim compared with a conventional rig. Furthermore, the mainsheet loading is only about one third of that on an equivalent stayed rig because the rotational force of the jib offsets that of the mainsail - hence a "balanced" rig.

Shorthanded passage making is so easy, the low sheet loads are so much safer with children on board, an Aerorig has no standing rigging to maintain, the visibility and space on deck are improved, sailing on a dead run is no longer a dangerous nightmare, jibing an Aerorig is a breeze, & short tacking to windward up a narrow channel is effortless.
Aerorig-unstayed-mast-unstayed-rig-shorthanded-performance-ocean-sailing-yacht
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Old 20-09-2009, 18:37   #10
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Thaks Aussie...

I think I now understand the advantages... that is a hell of a mast isn't it... wonder what that thing must weigh ??? But it is being used on a Mono which I could see would have MUCH more strength than a CAT given you could hold it fast in the Keel and again well up around the saloon ceiling... not that much leverage available on a CAT...
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Old 20-09-2009, 20:20   #11
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Well, you still have the main sheet and the jib sheet? So where is this ease of handling? No kicker. ok, but most cats do not have kickers anyway. Not quite see this ease thing.

How do you control the mast? You cannot leave it free-wheelin', can you? How does the mast-control mechanism add to the ease of handling.

I like it as an idea, but can't see any benefits. Actually looks like much more prone to failure than the normal thing.

b.
You did not get the point
There is not much need to adjust main and jibb, the jib is on a rail, selftacking, you NEVER touch it as you always turn the rig.

Remember, the boom is elongated to carry the jib AND mainsail. there is no mainsheet in the old sense, unless you adjust for the belly in the sail, you do not touch the mainsail either, what you might call "mainsheet" here really comes to its name, the main sheet turns the entire rig (main AND jib)

The combined sails are always set close to the wind.That means, you always have a better air flow from the jib to the main on the aero rig.

No kicker as forestay (front end of boom) and dirk (to apply tension to the forestay) balance the boom anyway, once set, nothing to adjust


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Old 21-09-2009, 05:39   #12
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Interesting system and wonder how they sail.
I have not sailed one on a cat, but they are the standard rig on harryproas, which I design and build. There is a video of one in action at This is a 50'ter with the same righting moment and hence loads as a 40' cat. At the time it was built it weighed and cost about the same as a pro built alloy mast with stainless rigging. There is a thread on this list somewhere comparing the two. We also built and installed a ballestron rig on an overweight 38' open bridegdeck cat. The 50' mast had 30" between the top and bottom bearings and has now been sailing for 4 years without problems.

The advantages are:
Almost zero maintenance and nothing to wear out. No chafe.

The ability to completely stop the boat and to hoist, lower and reef sails on any point of sail and in any breeeze with the boat stopped if required..

Automatic depowering in a gust as the mast bends.

No need to mess about with poling out headsails or dropping mainsasils downwind.

Lower centre of gravity, so less pitching.

Able to use a much taller mast without increasing the rigging loads , and with only minimal weight increase.

As for efficiency, Richard Woods (cat designer) said: the rig works to 95% efficiency all the time. A conventional rig may work to 100% if you're an expert, but only 70% if you're not. For most "set it and forget it"cruisers this is a 25% increase in performance, which rates far higher than any other single thing you can do to your boat.

regards,

rob
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Old 21-09-2009, 09:50   #13
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I like it as an idea, but can't see any benefits. Actually looks like much more prone to failure than the normal thing.

b.
It's a rotating mast. Cleaner entry angles for the mast/mainsail, no blanketing on a run, easier to handle and no downside, except for the price.

These rigs are better on just about all points of sail. I'd argue they could possible point better as well. Perhaps you have to be out on a cat that has one before you can appreciate them.
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Old 21-09-2009, 10:52   #14
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Well...

Aerodynamically, on most points of sail, this rig is LESS efficient = potentially slower.
Technically, it is more point stress loaded = easier to break.

I think the benefits are only to a lazy sailor who wants to control a big boat with single line. (Do tie the preventer though - unless you want to crash jibe - will the rig take it ?)

I like it, I like all things that push the limits - some of them break, but all of them add to our understanding of what works and what does not (sometimes 'does not YET' - it all varies with the materials we have available to build the boats, the sails and the rigs!).

Hugs,
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Old 21-09-2009, 11:34   #15
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Well...

Aerodynamically, on most points of sail, this rig is LESS efficient = potentially slower.
Technically, it is more point stress loaded = easier to break.

Hugs,
b.
I'm struggling to understand how you can make a flat statement that a rotating mast can be thought of as less efficient than a fixed mast???? May I ask, what textbook might that be in?

I'm fairly certain you've never sailed a cat with this type of rig and think you should come on down here and sail one before you take your comments further. They sure do look funny but are great rigs. The reason all boats don't have one is aesthetics and economics, not performance.
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