Why are these sytems not more popular? (long post)

[KellysEye]

Aerorig. Good friends of ours had one and eventually changed it to to a traditional Bermudan rig, keeping the same mast with a stainless strap to attach the gooseneck (this is tricky and they used an aeronautical engineer to design it). I think it was lack of sail plan flexibiity but the fact there are so few says it all really..

We have a Twistle rig - fantastic piece of kit. The beauty of it is you have an infinite number of sail(s) sizes and much easier to fly than a spinnaker (which we also have). Somebody said you can only sail it downwind. That's total nonsense - pull in on one sheet, ease the other and you can sail at least thirty degrees of the wind.

Not come across anyone with a Dutchmman system.

 

[Tranona]

Perhaps you are looking in the wrong place. The majority of production boats are now built with furling mainsails. May not be true in all markets, but biggest volume is warm weather and charter markets where furling sails are almost universal.

That is the problem with new rig developments - they have to capture the new boat market as retrofitting is usually not economic. But think back 15 years when furling mains were an oddity, but had clear benefits for a big chunk of the market, so investment in R&D and production facilities turned them into mainstream products very quickly.

 

[Kelpie]

If I understand the concept correctly, is a 'Dutchman' just a series of vertical lines from topping lift to boom? If you were lucky enough to have a topping lift that ran clear of the sail leech, presumably you could fabricate this very easily, using the reefing point eyes to carry short loops of cord to keep the sail in place.

 

[Sybarite]

The vertical lines actually thread through eyelets in the sail so that it automatically flakes to both sides of the boom.

John

 

[Woodlouse]

The vertical lines actually thread through eyelets in the sail so that it automatically flakes to both sides of the boom.

John

Sounds like it could have several potential problems for people who like to do a lot of tweaking with the sail shape.

 

[ccscott49]

Twistle or twissle (after the childrens program twizzle) as some folk say is a good system and one which I designed my forward rig around, I have the poles and all ness, just need another yankee making, but cost has limited that at the moment!!

 

[snowleopard]

Aerorig.....the fact there are so few says it all really..

Illustrates my point exactly.

An interesting bit of history - the principle of the Aero rig was invented in the 1930s and fitted to a Bembridge Redwing. It was banned by theclass asociation because it was consistently faster than the rest of the fleet!

 

[ianabc]

Twistle rig....

I believe that the twistle rig for downwind sailing with twin jibs, dual poles and a universal joint was developed by a British engineer in the late 1950's or early 1960's?


Using 1/2 inch or 5/8 stainless steel rigging toggles with nylon washers between the stainless parts might make a useful universal joint, at least there would be no machining involved just welding the toggles to pipe to fit inside the chosen dual aluminium poles.

 

[Neil_Y]

and as the sail slides up and down, the lines wear through the eyelets and then the sail.
The vertical lines are also rubbing against the sail cloth in the same place all the time.

I used it on a Santa Cruz 70' which helped control the huge main when two handed, but for long term cruising I think there are too many wear issues.

Any opportunity for chaf (is that how it's spelt?) is bad,

 

[KellysEye]

>just need another yankee making, but cost has limited that at the moment!!

Since you are not racing perfect sail shape is not a major issue. A cheap second hand sail would suffice.

 

[Bosun Higgs]

The sailing performance is as good as a conventional rig to windward but LOADS better on a reach or running.

There is absolutely no technical reason why the rig should be any better on a reach sail size for sail size.

 

[ccscott49]

>just need another yankee making, but cost has limited that at the moment!!

Since you are not racing perfect sail shape is not a major issue. A cheap second hand sail would suffice.

Trouble is, all the second hand sails I have seen, are genoas and the leech is too long, I need a much higher clewed yankee, otherwise, I reckon the system would be unbalanced although I could give it a try, I have a spare genoa (I was given), with a luff tape for my furlex.
If you look at my avatar, you will see my yankee.

 

[beserksail]

aerorig power is hard to tame, that's what happens when an aerorig boat loses her steering

Roberto, sure I saw this boat on the Guardiana last summer.

 

[Sybarite]

The film on the web site shows how they go about avoiding chafe; first the eyelets have a large rim (about an inch wide it seems) and so the lines would rub against this rather than the sail cloth. Secondly there are flaps attaching the lines to the boom; these are tensionned when you want to bring the sail down. Thirdly the lines appear to be quite light. They don't take any strain when sailing nor when the sails are down. the aforementionned flaps fold down when the sail is lowered, thus releasing the tension. On this type of set up, it's difficult to see where chafe can happen.

If on the otherhand small eyelets are used and the vertical lines are kept under tension then I agree that would not work as far as chafe is concerned.

John

 

[ff_nick]

There is absolutely no technical reason why the rig should be any better on a reach sail size for sail size.

Aerorig maintains more consistent leech tension on jib = less twist. Slot remains constant.

 

[Neil_Y]

I agree with the theory and the design, but in ptactice that is what I saw.

Even loose thin lines constantly moving in the same place relative to the sail will be touching it at some point and over time thinner lines will probably wear more.

The grommets in the sail will be good when new, but again in practice you ave to lok at what will wear and what damage will result. Perhaps this guy had his set up badly or used it badly bit that also happens.

It's one of those nice ideas that has issues in practice, more so on a boat that is doing a lot of sailing. Maybe a normal use marine based 500nm a year boat will be OK for many years, this was on a cruising boat where we doing 10,000nm a year.

 

[snowleopard]

There is absolutely no technical reason why the rig should be any better on a reach sail size for sail size.

I guess from your comment that you don't understand how the rig works.

A sail is at its most efficient when there is laminar flow over it, in the close-hauled position, i.e. with an angle of attack of around 20°. When bearing away on a conventional rig, that applies to the mainsail up to the point where the sail touches the shrouds. After that it begins to stall. A headsail becomes less efficient as the sheets are eased and the slot effect is lost. Ultimately the headsail loses drive as it is blanketed by the main.

With the aero rig, the whole rig rotates to maintain the most efficient angle of attack. On a broad reach the boom is eased out up to 135° from the centreline. The slot effect is maintained throughout the range from close hauled to around 150° off the wind. The foresail is never blanketed by the main. On a dead run the boom is set square across the boat so that both sails re drawing.

The picture below shows the rig on a beam reach. The effect of the slot can clearly be seen.

Quote from the OP: "An independent test was performed by the Woolfson Institute using two Bénéteau 42.7's, one rigged conventionally (93 m²), and one with an Aerorig (78m²). The latter developed more power on all points of sailing - from 10 – 30% more."

 

[snowleopard]

Never sailed an aerorig, but the thing that always occurred to me about them was the lack of flexibility over what sails were set, it seemed to be almost impossible to fly the jib without the main. Not sure I'd want to give that up.

You have to change your approach. As you say, sailing with jib only is not an option because the rig will weathercock. The correct technique is to furl the jib as the first sail reduction before starting to reef the main. In strong winds a deep-reefed main works very well. Remember that you can de-power on any point of sailing by letting go the sheet because there are no shrouds to limit the travel of the boom.

 

[KellysEye]

>Trouble is, all the second hand sails I have seen, are genoas and the leech is too long, I need a much higher clewed yankee

Ah. I wonder if a sailmaker would do a deal to chop a genoa down to a Yankee, it's quite easy. Reasons to argue that with the sailmaker - cheap sail, quiet period of year. Good luck if you try.

 

[ccscott49]

>Trouble is, all the second hand sails I have seen, are genoas and the leech is too long, I need a much higher clewed yankee

Ah. I wonder if a sailmaker would do a deal to chop a genoa down to a Yankee, it's quite easy. Reasons to argue that with the sailmaker - cheap sail, quiet period of year. Good luck if you try.

I'll try that, but not in Barcelona, anybody there is bloody eyewateringly expensive.
Thanks, I didnt know it could be done.
I could I suppose contact Southern sails in Poole, who made my sails and get a quote for another yankee, if they still have the measurements and the computer model etc.