WishBone Sailing Rig

High Tacker (www.damsl.com)

Oops! Forgot to attach the photos to that last post. Here:

 

High Tacker www.damsl.com

Here's another video of Rainbow Warrior III. There are some sailing scenes about one minute into it:

http://www.youtube.com/watch?v=hhuSpD81FOQ

 

You are right.

There will always be fuel and there will always be people able and willing to pay for it.

But that is not what I was discussing.

I was discussing transporting goods over water for profit.

As fuel gets more expensive, either ever larger vessels must be built to lower the gallon/ton/mile ratio, or, failing that, alternatives to straight fuel driven vessels will most likely be used.

When I say this, I'm talking about smaller vessels which must be small to get to out of the way places.

Some day, some shipper, using such a vessel is going to discover that equipping such with sails (which will be used along with the engine most of the time and used exclusively only during the most favorable conditions) will lower his costs enough to make purchasing and installing such a rig a worth while business proposition.

There are any number of reasons sail boats aren't popular these days.

Power boats are more convenient and more versatile than sailboats which are either designed to get around cans the fastest or sail across the ocean blue.

It will take an astronomical hike in fuel prices to rule out straight power boats.

Until that happens (not likely in my life time), straight power boats will continue to rule the recreational boating market.

There are just too many alternatives to chose from.

Planing, semi-planing, power multihulls, and, finally, displacement monhulls.

 

Sharpi2,

I understand your point about commercial delivery. Its just that there have been several attempts I remember in the last 30 years and they were all disastorous (I sure wish there was a spell checker on this forum, like everywhere else in digital land) failures.

A recent development in my career at an aircraft factory, is my working in a "Affordability" team. Generally it is not too hard to construct an economic model for a change, against which you can check reality and unexpected problems.

Vague predictions just don't provide any way forward. I just wish the forum focused on what could be done, with some concrete way forward - even if it ends up being wrong and has to be changed.

Brave words, but I don't have "concrete" suggestions in this case - I don't understand commercial delivery economics.

 

Please...lets not get into a discussion of sail verse power, ...and where the state of future oil supplies will be. There are other subject threads on this forum that deal with those subjects.

We are interested in alternative sailing rigs here.

Thanks, Brian

 

My appologies, I really am also interested in the sail rigs.

Actually the cruiser boat information is interesting, but I want to understand a practical way to do something similar on my Tornado catamaran (20') for day sailing. Suggestions would be appreciated.

Of course, I still want the performance. Something about having cake and eating it too.

Marc

 

Hi, upchurchmr.

IMHO, the three main reasons for failure in sail assisted ships during the last thirty years are:

1.) Fuel prices are still too low for them to be competitive. A vessel is a large assortment of compromises. More of one thing usually means less of another. A sail rig structure is bound to get in the way of cargo loading and unloading operations. There is also the issue of speed. A vessel with a 300 ft waterline can easily loaf along at 8 or 9 kts, barely breaking a sweat. Under sail, it would take an exceptional amount of wind to produce the same speed. Now, it is cheaper to go faster and ignore the wind.

2.) Attempts that I have heard of went too far in the name of purity. The only purity a working vessel is permitted is purity of purpose. That is why commercial fishing boats look so ugly. Elaborate rigs with experimental technology have no place on a vessel that must earn its keep. Better to go with something modest and relatively cheap. Like a pair of gaff sails, made as big as possible, but small enough to be out of the way when not used. An S/D of maybe 5 to 7 comes to mind. A rig that small belays any pretense of being a sailing vessel. But the twin gaffs will probably pay for themselves in a remarkably short time. Even at today's prices. Such vessels have existed before, back in the time engines weighed hundreds of pounds per horsepower and had voracious appetites for coal, circa the 1870's.

3.) The vessels with which such attempts have been made on were too large. Even 300 ft is pretty large for a sailing vessel. This is because, as the vessel gets longer, the wave train it produces gets longer too. The longert the wave train, the lower the percentage of hull speed (1.34 * the length of the waterline in feet for knots) it must attain to reach a reasonable speed. Back in the 1980's, the Maldive fishing fleet started installing engines on there lateen rigged double enders. Cy Hamlin, one of my instructors, was involved in the project. There were many problems, all of which had to be worked out in the most affordable way possible. I only bring this up because the Maldive fishermen did not dispense with their sailing rigs. They merely cut them down to a slightly more manageable size. These boats were around forty to fifty feet in length. For even the fifty footer to reach 7 kts, it has to go 75% of hull speed, where a typical cargo vessel has to go only about 50%. So, to get a reasonable speed, the Maldive fisherman has to run his engine at a higher throttle. But a sailing speed of 7 kts is possible well within most wind conditions.

Institutional vessels, such as 'Rainbow Warrior', may well lead the way. This is because they really don't have to compete with other commercial vessels, but are not pure affectations either. Operating costs must be considered. The 'Maltese Falcon' and other super yachts may well end up becoming institutional vessels.

Sorry about the continued segue, Brian. I already had my comments written before I saw yours.

 

Sharpie2

Thanks for the answer. I'm done, perhaps you could start another thread?

I'm feeling bad about what we did to Brians Thread.

But what about my Tornado?

Marc

 

High Tacker www.damsl.com

Hello upchurchmr,

Apparently you are interested in trying an A-frame rig or something similar on your Tornado 20 cat? Daysailing, you say, still high performance, but maybe something safer, easier to handle, more like a cruiser?

If you already have the gear, the beam, etc., for carrying a jib at the center between the bows, probably cheapest and easiest would be an A-frame with just a jib and a mainsail on the centerline, both on furlers, no booms, like the SMG 50 mentioned several times in this thread,

http://www.sail-the-difference.com/..._of_the_easy_to_use_smg_catamaran/smg_50plus/

and Gary Hoyt's Manta Clipper is very similar (see first 2 photos below) although it has a boom on the mainsail.

Or, if you want to play around with a lot of different sail configurations, check out my Catbird Suite at

www.damsl.com

But I would suggest the PYRAMID RIG

It might LOOK more complicated, but another rig that I've experimented with is what I call the Pyramid Rig. It amounts to 3 windsurfer rigs pinned together at the top to form a 3-legged pyramid. All 3 masts rotate 360 degrees. Wishbone booms maintain sail shape on all points of sail. If you get in trouble, you just let the sheets go, and everything weathercocks. You can leave her sitting on the beach with all sails up, or at a dock or a jetty or tethered behind your big boat.

Construction is easy. 3 aluminum tubes of 1 inch circular section, attached to the boat, on hinges if you like so that the rig can be lowered easily, and a bolt at the top through the 3 tube ends all in a row with the jib tube in the middle between the 2 side mast tubes. Every couple of feet along these tubes there is a plastic bushing-type of bearing made of the same kind of stuff that you make prop shaft stern tubes of. These tubes are inner masts and then there is an outer sleeve for each of them and the outer sleeves are 2-inch luff spar sections that slide on over the plastic bearings. So then you have rotating masts which are very strong and can take a lot of bending from the wishbone booms and still rotate around those plastic bearings. The booms are hinged onto pins on the outer mast sleeves.

See the photos below. That tiny jib was ridiculous and I later got a big jib that filled up the foretriangle between the jib mast and the two side masts. I had the little jib made before deciding to go with 1 jib mast in the center instead of 2 jib masts, 1 to each bow. That would have made a 4-legged pyramid. This little cat was actually built as a powercat meant to be driven by an outboard or two, and so it's narrow in comparison to sailing cats, hence a small jib if it had to swing between 2 masts at the bows.

I don't have photos of the big jib, but it was made of dacron. The plastic sails were on the advice of the sailmaker, because a lot of windsurfers had plastic sails. But that was a mistake and I much prefer cloth sails for a number of reasons, not the least of which is that stupid birds will accidentally collide, beak first of course, with see-through sails. Who wants leaky sails?! And they are a pain in the *** to hoist up the groove of the luff spar and to take down, because they have to be rolled up, not folded at all. Dacron will take a lot of punishment.

If I did this rig again, I think I would go with the 4-legged version on a beamier cat, but shouldn't get too long-winded about that here.

You can imagine the advantages of such a rig. You can make it as tall as you want for performance. Yes, there is of course a weight consideration, although I think it could be built of much smaller and thus lighter sections than what I used. I don't think it would be all that much heavier than the conventional rig on a Tornado. And the weight is balanced by the smaller, or re-directed, heeling moment that you get from slanted sails in such a biplane rig, that is, the 2 side masts form a biplane, one side of which is pushing the windward hull down, and the other side is lifting the leeward hull. And since the sails can rotate, you just let them go when heeling gets critical, and they just weathercock. With the wishbone booms, they don't flog like with a conventional boom.

It's very safe downwind, because you let the sails rotate beyond 90 degrees to the wind, so that they are always taking the wind on the proper leading edges and there is no danger of jibing. And do you have trouble reefing your big conventional main downwind, or getting it down? This rig eliminates all that bother. You just let the sheet go, and the sail weathercocks and there's no shrouds in the way.

Anyhow, have a look at the pics below. Note that in some, I was experimenting by using one of the mainsails as a bigger jib, before I got a big cloth jib, and in that makeshift arrangement, the forward end of the boom, where it is attached to the mast, was not high enough, hence the sail shape is not right. Also, the cloth jib was much bigger, its boom much longer.

Note that when the little cat was tethered behind the big cat, with no wind, all the sails fall toward the center, but when the wind got up, they would just weather cock. So I just detached the sheets and left her with sails up. As I said, the plastic sails were a pain in the *** to get on and off.

I sometimes wish I'd done this rig on Catbird Suite, but it would have been much more expensive than the A-frame, because I would have wanted to do it of carbon fiber. Also, the A-frame leaves lots of room for experimentation.

Note that this pyramid rig is very strong. There is very little compression on those masts. And, unlike the vertical bipole rigs on a few cats, which do not have the masts connected at the top, there is no big complication of strength and rotating gear at the base in the pyramid rig, because there is no big bending load at the base, indeed, the masts can be mounted on simple hinges for lowering. Note, too, that there is no great tension involved either, as in conventional rigs, so no need for chain plates.

There is some bending load on the masts from the wishbone booms. It's amazing how much bending the masts can take when there is very little compression. And when bent, they can still rotate when you tighten the sheets, albeit with a little groaning from the plastic bearings. Of course, when you slack the sheet, the bending load is relieved and the mast rotates without complaining. All in all, there is no danger with these booms. They're over your head and there's nothing else for them to bash. But you can dispense with booms if you want, and just not use the leeward mainsail when reaching. Just like with the A-frame, you can sheet down to the boat.

Oops, I somehow managed to delete the first two photos, of Gary Hoyt's Manta Clipper, will attach them to next post.

 

High Tacker www.damsl.com

Here are the pics of Gary Hoyt's Manta Clipper, which may actually have been mentioned and shown already on this thread, sorry if this is repetitious.

 

Actually the 'Manta' subject came up several times before. This gentleman even offered that he had some old brochure material....but he never posted it to my knowledge
http://www.boatdesign.net/forums/boat-design/wishbone-sailing-rig-1999-2.html#post26593

Thanks for those pics...don't find them that often.

 

High Tacker,

How much sail area did you carry on Lagoon Hopper? What was the mast height? What was the boat length? Did you have a back stay to the peak of the 3 masts?

I assume that when you were on a broad reach the leeward main was badly shadowed and developing no power. It also seems that hard into the wind the jib would shadow the leeward main. Please comment.

You might not be aware, but there was a Pyramid rig discussed by AYRS in the 70's, but it had a central mast with 2 jibs that rotated around the mast. In that case nothing was shadowed until you went directly down wind. I never hear of a real report of the practical aspects.

Marc

 

High Tacker www.damsl.com

Hello upchurchmr,

This pyramid rig was very quickly put together and tried, because I had already pretty well decided to go with the A-frame for the big boat, with all furling and boomless sails. But I wanted to give the pyramid a try, and I'd like to see somebody carry on with it.

Sorry I don't remember the exact numbers you asked for, but a lot has gone in and out of my old noggin since then. Am pretty sure that the aluminum tubes used for the inner masts came in 5 meter lengths, so the side masts would be exactly that, with the heads of the sails about a foot below the peak and the foot of the sail about 3 ft off the deck, or enough for sitting head room. The jib mast is longer, so some tube was added to the 5-meter length.

By rough estimate, the rig is just over 15 ft. tall and mainsail area would be considerably less than 40 sq. ft., maybe closer to 30. Sorry, was dealing in sq. meters then and don't remember that either. The jib we finally got was somewhat bigger than the mainsails. Boat length is 14 ft, and as I remember, beam was less than half that. The boat, with rig, is still sitting on the beach in New Zealand, with weeds growing up, through, around and over it, so it ain't goin' nowhere, and I'll be back there in November, and the sails are stowed away there. If you're really interested in exact numbers, I'll get them for you then. But you would want a much taller rig anyhow. This one was very conservative.

There are two backstays, to the stern of each hull, or, rather to the corners of that stainless frame, which then has posts in the same lines to the sterns. The mainsails are sheeted to that frame. The jib mast is stepped on just a 1-inch aluminum tube across the bows and I thought that backstays were necessary to prevent too much downloading on that. So the side masts take a bit of compression, but not much because the sails are all on masts, not wires.

You're right about the jib blanketing the leeward mainsail when hard on the wind. We were able to go to about 35 degrees apparent, with the jib sheeted right to the base of the leeward main mast, in other words, just to the leading edge of the leeward mainsail, so they were sort of acting as one sail. But it was possible to go quite a bit closer to the wind by pulling the jib in tighter, but that de-powered the leeward main. I forgot to mention it, and the post was already getting long-winded, but one way to solve that, or at least improve it, is to have the two side masts closer together. The mains would then be narrower, but you could make the rig taller, have very high aspect ratio mains. Note on the SMG 50 that the masts are stepped apparently on the inboard gunwales of the hulls. But I don't know the beam of your boat. Actually, there's so little compression on the pyramid masts that they could be stepped anywhere on deck, on the bridgedeck, where ever.

This pyramid rig may appear to be heavier than the A-frames, but I don't think that has to be so. There is not nearly as much compression loading, almost negligible in comparison. And the tube within a tube structure, with bearings between the two tubes, is very strong. The outer tube is reinforcing the inner tube. There is a very precise formula for calculating how close together the bearings should be in terms of compression. I've forgotten the formula, but if you don't know it, a good designer could do the calculations for you, or you could look it up. But I think you could go a lot taller with the same diameter and wall thickness of tubes. Compression can be carried around a curve, the trick is just to have those bushing type bearings as close together as necessary. And with the wishbone booms, the masts WILL be bent. How much you can bend the masts is the question. We did add some short sleeves onto which the booms are hinged, to spread that rather than have point loading. You might want to spread the boom load even more.

Another way to deal with the jib and leeward main relationship would be to have a curved track at the base of the jib mast, so that the tack of the jib could swing to leeward, say, almost to the leeward bow. I had thought of doing that, but after deciding to go with the A-frame, I never got around to trying it. If you read some of my long-winded explanation at
www.damsl.com, you'll see what I mean by advantages in moving tacks of sails around.

What I had in mind for a track was to take a length of that 1-inch aluminum tube and bend it to the arc that the base of the jib mast would transcribe in swinging from one bow to the other. The jib mast could be stepped to a ring that would slide along that tube, with a stop at each end of the arc.

Then the tacks of the jib and the leeward main would be more or less in line, fore and aft, and you could get little a slot effect between them, although they would not overlap, of course. I think more important than that, the jib, as well as the leeward main, would be canted into the wind, so that the leeward side of the boat, especially the bow, would get some lift, help keep her from tripping over the leeward bow.

Also, for downwind, you could pull the tack of the jib to one bow or the other, so that the jib would fill the gap between the mains, which you would wing out on either side.

There's actually less interference than you would think between the two mains, except for a small range beginning with the wind just forward of the beam. Once the wind is abaft the beam, everything seems OK, although I found it difficult to judge sometimes with those thick plastic sails. I think what's needed is experimentation using very light cloth sails.

 

High Tacker www.damsl.com

upchurchmr,

I think I know of that other pyramid rig you mentioned, or, rather, one that I know of, also called "pyramid" had 2 jibs (or triangular mainsails) which formed opposite sides of a 4-sided pyramid, so the 2 sails formed a biplane canted together at the top in the same way the mainsails on my pyramid do when they are sheeted so that they are parallel to each other, as when pointing. Yes, on that rig, the sails were always parallel to each other, the mast in the center rotated and the sails rotated with it, then one sail would blanket the other when the boat was headed downwind. A friend of mine, a Brit in New Zealand, Neville Skit (not sure of spelling, so long ago) did that rig on a cat, the Golden Kophai, in the 80s. It had some practical advantages. The pyramid was in the center of the boat and he had a big genoa that he would move from one bow to the other, with a wire between the bows as traveler. My girlfriend and I sailed around Fiji with Neville and his wife Sheila on that boat for a couple weeks, in the early 90s, and then again for about a week down the east coast of New Zealand's North Island.

 

High Tacker,

Thanks for all the information. It should be enough, just knowing the height of the masts gives me a good understanding, along with the length of the boat. My goal would be to put more sail up than the normal Tornado, on a shorter mast height. The old classic Tornado was limited to 235 sq ft. on a 31' mast. Of course it doesn't really work if one of the mains is blanketed.

Thanks,

Marc