Anyone Ever Sail a Cat with an Aerorig?

[TaoJones]

Originally Posted by rob denney

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.

Actually, it's an even greater increase than that! Increasing efficiency from 70% to 95% represents an almost 36% increase in performance (25 is 35.7% of 70.)

TaoJones

[barnakiel]

Originally Posted by Tropic Cat

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.

I mean the whole rig - the mast, boom and the sails, and not in the general context, but as meant in the specific context - "one line control'. Have not sailed, not many of them around. Have seen one broken though - Richards Bay, RSA. On a cat (a small, not offshore, cat). I do not think they look funny, to me, they look cool. I hope the explanations remove the 'struggle' and 'flat' factor somewhat ;-) b.

[Nordic cat]

Barnakiel, why do you think this rig will be less efficient than a traditional bermudan rig?

You talk about point loading, how many tons of mast compression would a medium sized cat (40-50 ft) have to handle? 3 to 5 tons maybe?

The Ballestron rig for such a boat will weigh maybe 200-300 kgs max, so less than 10%. So your crossbeams can be lighter as well.

These rigs can be improved slightly by using a wing shaped mast that rotates a bit relative to the boom, then you will be as least as efficient as the best bermudan rigs hard on the wind, that for this rig means nearly all points of sail.

There are 70 and 80 foot boats that have been using this kind of rig for 15 years and more.

Why don't we see more of these? Looks, and conservative thinking that is prevalent amongst the large majority of sailors

Been on a plane recently? Did you notice that they use unstayed foils, in aluminium, not even carbon!!!


Alan

[barnakiel]

Neither VOR, VG, Minis, Open 40, AC nor any radical modern class (Moth, skiffs, etc) use this rig. They are not limited by cost. If it were faster, they would have used it in racing. Because racing is all about speed.

I do not see how this rig can be efficient reaching - the jib travels to the windward of the main and keeps the slot narrow (too narrow). I believe to some extent this can be made up for (actually perhaps even bettered out) by managing the rig's angle, so that the pull is directed with more forward vector (converting some heel into forward pull).

Broad reaching and downwind, the rig is limited by by the limited size of the jib. I believe this rig would have to be huge to match a classic rig with a kite, downwind.

The issue of compression forces versus breaking forces is better left to engineers - in any case since they use the classic rig rather than the aero in 99.9% of the designs, it seems that it is easier to manage (engineer for) compression. This particular rig has no give and its stiffness combined with the inherit stiffness of the cat's hull characteristics may further worsen the situation.

I disagree with the statement that this rig is nearly always hard on the wind. Perhaps on a racing cat this would be the case, however on a cruising cat or a mono this rig will work exactly like its classic counterpart. Thus, the advantage of being always hard on is not feasible.

The pseudo-argument on plane vs. boat construction cannot not be addressed other than by pointing to the fact that water is somewhat denser than air and airplanes seem not to be anchored in this denser enviro by having a foil (a.k.a. keel or daggerboard) seriously limiting the hull's freedom of movement and so creating huge forces on the hull-rigg joints.

I also disagree (again) with the aesthetics issue - to me this rig looks great, I simply do not see it as the better/best rig around.

b.

[rob denney]

G'day,

My comments follow yours, but I strongly suggest you sail one before you decide against them.

Originally Posted by barnakiel

barnakiel: Neither VOR, VG, Minis, Open 40, AC nor any radical modern class (Moth, skiffs, etc) use this rig. They are not limited by cost. If it were faster, they would have used it in racing. Because racing is all about speed.

Rob: Stayed rigs are rule driven (mainly sail area, but also mast height) and have hundreds of years and millions of dollars of research into them. Check out Wylie cats in San Francisco for an example of an unstayed rig that is quick. The proa in the video is also pretty quick, I don't know of any other videos of a cruising boat costing less than half a million bucks with similar accommodation sailing at windspeed in 15 knots of breeze under plain sails. The ballestron rig is a cruisers rig. It outperforms other cruising rigs. It does not outperform a racing rig sailed by experts. One of a few racing boats to use an unstyayed rig was Kyote 2. It was banned after it won it's first race.

barnakiel: I do not see how this rig can be efficient reaching - the jib travels to the windward of the main and keeps the slot narrow (too narrow). I believe to some extent this can be made up for (actually perhaps even bettered out) by managing the rig's angle, so that the pull is directed with more forward vector (converting some heel into forward pull).

Rob: Reaching, they are superb. The jib works without being barber hauled down or out and is easily adjusted to every puff if required. The heeling force acting straight ahead instead of sideways is a large advantage. In the boat on boat tests I have read (Sigma 36 and Hirondelle catamaran, plus some wind tunnel tests at Southampton), reaching (and ease of handling) were the ballestron's relative strong points.

barnakiel: Broad reaching and downwind, the rig is limited by by the limited size of the jib. I believe this rig would have to be huge to match a classic rig with a kite, downwind.

Rob: It could be much larger than a stayed rig. The boat with the spinnaker has had to drop his jib to allow the spi to fly. The actual sail area flying is not that different. Many cruisers drop their main when they raise the spinnaker making ot even smaller. The ease of use difference is enormous. I have flown a spi on a ballestron. Works well.

barnakiel: The issue of compression forces versus breaking forces is better left to engineers - in any case since they use the classic rig rather than the aero in 99.9% of the designs, it seems that it is easier to manage (engineer for) compression. This particular rig has no give and its stiffness combined with the inherit stiffness of the cat's hull characteristics may further worsen the situation.

Rob: See my previous post about loads and costs. Unstayed rigs have enormous "give". It is one of their safety features. An stayed rig has up to 100 individual parts, any one of which can fail and the mast falls down. An unstayed rig has none. Designing an unstayed rig and the structure to support it is simple, compared to a stayed rig. Our engineer charges $1,000 for the unstayed, from $3-10,000 for the stayed, depending on how racy you want it to be. Most designers just copy other boats' rigs. Hence their popularity from their point of view.

barnakiel: I disagree with the statement that this rig is nearly always hard on the wind. Perhaps on a racing cat this would be the case, however on a cruising cat or a mono this rig will work exactly like its classic counterpart. Thus, the advantage of being always hard on is not feasible.

Rob: I think that what was meant was that the rig can be rotated so it sees the breeze at 35-40 degrees (until it is running square), rather than that the boat is going fast enough to move the apparent forward.

barnakiel: The pseudo-argument on plane vs. boat construction cannot not be addressed other than by pointing to the fact that water is somewhat denser than air and airplanes seem not to be anchored in this denser enviro by having a foil (a.k.a. keel or daggerboard) seriously limiting the hull's freedom of movement and so creating huge forces on the hull-rigg joints.

Rob: Does your boat have a stayed keel or rudder? Ever thought why?

barnakiel: I also disagree (again) with the aesthetics issue - to me this rig looks great, I simply do not see it as the better/best rig around.

Rob: It isn't if you are in the sail, mast or rigging business which is where most rigging advice comes from. It is also not the best if you have a hot shot crew that likes to spend all day tweaking strings. It certainly isn't if you are a typical conservative boat owner, more worried about looks and resale value than ease of sailing, safety and cruising speed. Where do you live? I may be able to get you a ride on one.

[barnakiel]

OK then, I will try to get a ride if I come across any of them. I met them only twice by now - once on a Spray mono in Pacific Panama, once on a smaller cat (broken up) in Richards Bay, RSA. I have read a couple of things on the rig too, but they were all written by people who were designers / builders of this stuff - and as you noted yourself - what else than praise can we hear from the seller of a specific product. The only unbiased thing I found was a passage in Marchaj's book.

If you can direct me to any online, independent and unbiased tests / reviews of this rig I will be grateful.

I like some of what this rig offers - like being able to ease the sheet and just spill the wind off the sails in a puffy downwind situation - impossible with all the many stays of the regular rig.

As I said I do like the looks, but I do not buy the horse by the looks. So if the rig works as well as it looks who knows what I can put on my future boats.

b.

[rob denney]

I meant to put this in my other thread. The downside of the ballestron is the difficulty in getting a tight forestay, which compromises heavy air windward performance. Runners help, but are extra mucking about. Upwind in a breeze, I tend to remove the jib and just sail under main.

Unstayed round masts are also more windage than a stayed mast, although once you add the spreaders and wires of the stayed rig, it is a lot closer.

Both tests were in English magazines, so try Practical Boat Owner, Yachting World and Yachting Monthly. Carbospars paid for the Soton wind tunnel tests as far as I know, so you will probably discount them. This would be a mistake, in my opinion. While I (and Carbospars) praise the rigs, it is supported with reasons that you can and should analyse. If you discount the reasons due to percieved bias, you are dooming yourself to maximum effort sailing and expensive maintainence of your standard rig.

Any more details about the busted rig in SA would be appreciated. I heard about an unstayed bi rig (Schionning Radical Bay) breaking it's mast there, but not an aerorig.

Tao, thanks for the correction. Richard's fondness for exageration and hyperbole already cause the case to be overstated, I did not want to make it any worse. In reality, if the difference is 20% of actual speed for the average cruiser I would be surprised. The benefits of the ballestron are all about ease of use and lack of maintenance, the improved performance is a bonus.

regards,

Rob

[blubaju]

Originally Posted by barnakiel

If you can direct me to any online, independent and unbiased tests / reviews of this rig I will be grateful.

I like some of what this rig offers - like being able to ease the sheet and just spill the wind off the sails in a puffy downwind situation - impossible with all the many stays of the regular rig.

As I said I do like the looks, but I do not buy the horse by the looks. So if the rig works as well as it looks who knows what I can put on my future boats.

b.

I had one for nine years and it was fine
I will not have one on my new cat and I worry.

My cat designer put a huge roach on our mainsail, becoming standard nowadays on cats, no way to do this with the aero or your mast will be far to heavy. As Rob pointed out, some designs have a problem tensioning the forestay, that can be corrected with the "dirk", giving you a strong triangle boom-forestay-"dirk" with the mast as center.

For the average sailor the aero is the easiest rig, you release the mainsheet and jib and main together are out of pressure. Jibbing is easy as the wind pressure on the jib counters the one on the main, the boom comes over in a controled manner, no need to be scared from an accidental jibe.

It is not a rig for a racer who wants to adjust and control sailshape all the time, mast hight is lost as the top triangle of the sail does not contribute to force compared with the square tops in fashion now. And that is the reason why I choose the bermudian rig, my mast would have grown far to high for the same sail area - I am sure I will miss the easy sailing of the aero.

[barnakiel]

Originally Posted by blubaju

... For the average sailor the aero is the easiest rig ...

Agree it looks very easy to sail. I would pick the cat rig even above it (like seen in a Laser, OK Dinghy or Finn class) and Freedom cat ketches as well as some Hereshoff (excuse the heresy of spelling) cat boats serve as working examples.

And the power derived from the old but now gaining field wide top keeps the rig shorter. I love it.

Actually, the Freedom 35 or so cat ketch would be my pick for an easy boat, if not for my reservation to their hull shape (and entailed ocean going limitations).

b.

[wingssail]

Originally Posted by blubaju

It is not a rig for a racer who wants to adjust and control sailshape all the time,

It is also not the best if you have a hot shot crew that likes to spend all day tweaking strings.

This is silly. You guys have written purportedly this to be a negative for Aero-Rig, (the hotshot crews who want to tweak all day won't like it) but actually you believe that that this will be interpreted as a positive since it means, by implication, that normal rigs require constant tweaking, and as further discouragement for a normal rig, if you have one you might need, or have to put up with, a hotshot crew on the boat who is bent on tweaking all day.

And who, in their right mind, would buy any rig for the purpose of satisfying some hotshot who might want to come on board and tweak it all day? (Answer: Nobody)

But anyhow, it isn't even true that a normal rig requires or encourages tweaking all day, or even often. We have a very conventional rig, we set our sails, trim them, set the wind vane, then go onto our watch schedule. We don't tweak anything all day. (if the wind changes, yes, we make changes to the sheets. So would the Aero-rig owner)

Stop using that red herring.

[Training Wheels]

I think he stopped using the herring 9 years ago!

[cyan]

Originally Posted by Training Wheels

I think he stopped using the herring 9 years ago!

Herrings stink up time machines.

[Greg4cocokai]

Here’s a pretty one near me in Mexico

[owly]

There seem to be a lot of folks that can't imagine how an unstayed mast could work on a catamaran... as if somehow the loads would be greater than with a stayed rig.... Obviously this is anything but the truth. The result is that one sees biplane rigs with unstayed rigs, but almost no single masts. The biplane means more weight and more parts. It also means the mast step is below waterline instead of above it.... which means about 4'-5' more mast for a given air draft.


The Ballestron rig is a very heavy rig, and complex with it's rotating mast. The rig that appeals to me is the Aerojunk, designed by Paul McKay. The Aerojunk instead of having separate panels separated by battens in pockets as with a "real" junk rig, uses light weight battens which form a cage. The main and foresail both fly inside this cage. The sails are flat fabric, and they derive their camber from the cage. It is possible to change this camber easily, but not while the sail is up. The cage shifts from one tack to the other so the turbulent slipstream of the mast does not impinge on the airflow across the sail.


Like the Ballestron rig, one sheet controls the works, and there is an unstayed mast. Unlike the Ballesron rig, there is no sail track. Unlike the Ballestron rig, the fore and main sails reef together, and they reef effortlessly and without any fancy furling or reefing gear, stacking neatly with no need to tie in reefs..... reefing is simply a matter of letting go some halyard. The sails are tied to each batten. Pete Hill's Oryx currently flies a biplane rig based on this design, but not quite adhering to it. You can find photos of the original version here: http://www.voiles-alternatives.com/d.../aerojunk1.jpg


and here: http://www.junkrigassociation.org/re...9/IMG_0227.jpg


You can find a PDF describing it here:
https://www.google.com/url?sa=t&rct=...RYAun3D-vFkcGS


And of course Google will fill in the blanks......

[wingssail]

Originally Posted by owly

and here: http://www.junkrigassociation.org/re...9/IMG_0227.jpg

Simple it's not, and it doesn't look too rugged to me either.

I am constantly amazed at the extent people go to try to invent something which works better and more efficiently and a standard sloop rig on a stayed mast.