WishBone Sailing Rig

[ChiefOren]

Thoughts on the A-Frame

As I am building a 50 George Buehler sailboat, I plan to incorporate the A-Frame concept with the Aft-Mast configuration. In this way, I can eliminate altogether the Main Sail, and instead incorporate 2 Gibs that will do the work. I may in the future add a mizzen, but at first I will try without. I am very interested in others that have tried the A-frame, and would also like to know what others think of the Aft-Mast.
Thanks for the update.

 

[gar37bic]

To much time on the computer not enough time sailing.
Daniel

That is a strange boat - if nothing else, it seems to take 'windage' to new highs.

 

[gar37bic]

As I am building a 50 George Buehler sailboat, I plan to incorporate the A-Frame concept with the Aft-Mast configuration. In this way, I can eliminate altogether the Main Sail, and instead incorporate 2 Gibs that will do the work. I may in the future add a mizzen, but at first I will try without. I am very interested in others that have tried the A-frame, and would also like to know what others think of the Aft-Mast.
Thanks for the update.

Chief, I suggest you take a look at some of the pictures and specs of my boat - I've posted the link above but here is a link to the pictures: http://www.sail-works.com/KOLIKA/html/picture_gallery.html

Here's a good picture of the rig. One thing I don't understand is why he left the bottom of the mainsail so high. It looks to me like I could get the foot of that sail another 'foot' or two longer/lower, improving the sail efficiency. But the builder did put some hardware at the front of the wheelhouse that sticks up a foot or so, so maybe that's why.

 

[ChiefOren]

I have seen this, and was very impressed. The difference though, is I wish to rake the mast forward as per the Aft-mast configuration, and use three stays, which will be used as two gibs and a permanent Storm Sail. I could then in the future also incorporate a ketch, but for starters, I could do without. Thank you for the link to your site. I had it on one of my earlier computers, but it went out with the hard disk that I had to replace. Could you give us some of your thoughts on the A-Frame, and how it worked out?

 

[gar37bic]

Solid Backstays are dangerous. They can snap, and you cannot redily fix them. It is far better to have lines that can strech a bit and aleviate the stress on the masts. Remember, the masts are working with the wind, and if they are too rigid, the fatigue of the metal struts is much greater. I'm sure George agrees here. I plan to have an A-frame aft-mast rigging, and the back-stays are going to be hefty galvanized lines. Better to go big on lines, but avoid rods. At least with the lines, they don't usually fail at once, but you can see one or two strands that snap, and you have an indication of what's to come. But if the rod, or brace breaks, the intire rigging will go, without notice.
Good luck with your project.

I am reminded of an analysis by Navy scientitsts that I read long ago, about the chinese junks. One of the big differences that was noted was that where USN ships were built strong and stiff to resist the forces of nature, the junks were flexible and stretchy. This made them possibly less efficient, but more adaptable to extreme conditions - like a palm tree vs. a big oak.

 

[gar37bic]

I have seen this, and was very impressed. The difference though, is I wish to rake the mast forward as per the Aft-mast configuration, and use three stays, which will be used as two gibs and a permanent Storm Sail. I could then in the future also incorporate a ketch, but for starters, I could do without. Thank you for the link to your site. I had it on one of my earlier computers, but it went out with the hard disk that I had to replace. Could you give us some of your thoughts on the A-Frame, and how it worked out?

If you're talking to me, I am no expert, and haven't even sailed my boat yet - I'm still fixing it! So I can't say anything from my own point of view. But the original builder was happier with the overall results than even he anticipated.

I did post a couple of items about the aerodynamics in post #150 a little while ago - you may not have seen it. But I will say that the masts indeed are very light - I think about 200 lbs. each even with the hardware. They have an airfoil shape with an internal cross-membrane - the cross section looks like a figure 8.

I'm unfamiliar with the aft-mast thing you are talking about. How does that work? Is it akin to 'suicide doors' on the old cars?

 

[gar37bic]

I should mention that the masts are over 52 feet long.

 

[ChiefOren]

To start, you could look at www.runningtideyachts.com to view the Aft-mast configuration. The Idea is to rake the mast forward about 10% and connect to it two Jibs, eliminating the Main Mast and Boom. I thought, gee, nice, but wouldn't it be more reliable with an A-Frame? So by combining the A-Frame in an Aft-Mast configuration should actually bring a lot of benefits.

 

[ChiefOren]

Also, with the Aft-mast rigging, the sails would not overlap the masts like what we see in the above picture that you sent. This would allow for closer hauling of the sails, maybe even using sail tracks on the deck for sharper tracking.

 

[TTS]

Sounds a bit like this tilting rig concept from Chris White:
http://www.wingo.com/chriswhite/tiltrig.html

Actually I can not see the benefit of moving the tack, nor luff of the main (Wait a minute, I take that back. There could be some benefits, but it complicates things even more).

If anything the Aero-Rig was pretty efficient at keeping a constant relationship between the jib and main.

I know that htis is an old thread, but my question about this is, does anyone know what the platform that this rig is on? IE, hulls and are they planing hulls?

 

[brian eiland]

Any updates to report?

I have some interested parties who persist to ask questions about this designer and his reasonings.

I've recently been contacted by a gentleman who claims to have some blueprints of the taller rigged vessel. He refers to her as 'Nimrod'. We show a photo with the name 'Relentless'.

Possible he will be able to shed some other light on the designer and his work?

Meantime he referenced me to some other photos:
http://www.nahiku33.com/mw.html

 

[Kojii]

Relentless nee Nimrod

It was Nimrod. The photos shown were taken at Railway Marina, where we are now moored on Puget Sound.
As in my other posting (other thread) Nimrod/Relentless is now at John Wayne Marina and has had it's keel removed (it did not go willingly), mast shortened, power plant upgraded, and a doghouse stuck on the stern. It is not the same boat. Still has a get home bipod rig only.
I have the DWGs for the boat also. Since the boat had long since been sold by the original owners before it got to Railway, I doubt any new light will be shedding, but I'm just a skeptic...
Orca remains intact.

 

[brian eiland]

I have reviewed a lot of the observations and precepts/opinions and most everyone is "correct". Paradoxically, the boat sails well mainly because the hull is a racing hull. So this will never be a popular boat. Slack bilges, close quarters below, and tight deck space - but what a beauty in the slings....
The wishbone legs are bowed (cleverly), and require pre-loading, if you will, by the shrouds at the mid-arc to keep them from springing (they are afterall bows of carbon/kevlar/plastic). The wires do the trick as designed. As such the bowlegs of this mast act as shroudmasts with the wires performing the role of the string on a bow, only this string is attached in the mid-arc.
Shortening sail does result in lee helm but not a lot. I have not yet been able to get it to heave to. Still working on it. Fore reaches fine.
Tension loading is "extreme" I suppose. I have bent the upper mast back a few inches to get high tension of the forestay. Replaced some turnbuckles on aft stays but they were not badly worn. Rig is heavier than I would have liked, but necessarily so for strength. Still not much different from standard Marconi with same sail area and probably a little less weight depending or reefing of the Marconi reefing system. This is all anecdotal from my yard experiments, mainly involving my back, which has been a reliable tool thus far.
Aero-hydrodynamically speaking, the thing works well. I did hang it in the yard but the scale was broken...
Very comfortable ride to wind and on a reach she goes. Ran into the harbor last week with 20 knots of wind doing 8 knots without much fuss. Keeping the staysail boom down is a problem. I like sharpieII's ideas and observations.
Many of the observations of the individuals are right on and I appreciate the spirit of the discussion, unlike so many forums on the web, this one seems to keep it neat and respectful. I appreciate that more the older I get.
This will not likely ever be a "popular" rig for many reasons but primarily because it requires a very lean hull to take advantage. Most people just want real estate below and on deck. I do feel safer on it than on the vintage open 60 however. I know this one will come back up...

Just ran across this photo on my computer and thought it fit this description pretty well. I don't think it has been posted?...and I'm sure Kojii must have sent it to me.

 

[Kojii]

Hove to

Just wanted to add that a few days later we did heave to under staysail only. The boom made itself very useful. Very comfortable ride, well-balanced. Attached another shot from a blustery day some years ago in Oregon.

 

[brian eiland]

A-Frame Rig on 'Catbird Suite'

Somehow I missed ever seeing or knowing of this vessel, but here is a gentleman who is not affraid to experiement. Just happened across this vessel this afternoon. Perhaps we'll encourage the owner to add some comments to this forum.

http://www.damsl.com/

"The rig is my idea (tested on a smaller catamaran) with engineering and construction specifications by Malcolm Tennant and Anthony Stanton of New Zealand design team Malcolm Tennant Multihull Design (tennantdesign.co.nz), who designed the boat. Dave Pope, who was a member of the Tennant team, did the original construction drawings of this boat and has contributed a lot to development of the new rig. Dave now has his own design firm and is based in Whangarei (dpd.co.nz).

The rig was completed in December, 2006. It works very well, is quite efficient upwind, is especially good reaching and running, and is easy to handle because all sails furl and there are other advantages as well........."

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