Balanced lug sail questions

[smallyachtsailor]

Hi all. I'm planning on sewing a balanced lug sail (boomed) of about 85 sq. ft. area, and have a few questions. I've sewn sails before but not a balanced lug. The boat is a little daysailer of about 14 feet, and is cat-rigged. The old sail is worn out so in the process of replacing it, I'm converting the rig from a gunter rig (which I dislike) to a balanced lug rig. I won't need new spars, and there's no significant change in CE.

First question: Are balanced lug sails better if cut flat or with a belly? If not flat, how much belly and what shape? I plan on one or two reef points in the new sail, and its not a high-aspect ratio sail.

Question 2: Its been a while since I've sewn sails. Is dacron best or are there any other options now? I'm thinking tanbark color. And what weight of sailcloth would be appropriate? Its just a (fair-weather) daysailer so I just want something that will last a while and be easy to handle. I'm not looking to spend a lot--it's just a boat that will get me out on the water while I build my dream boat.

Last Question: Can anyone recommend a place (online or in S. New England area) where I can get a decent price on sailcloth? I'll probably get a bunch because I do hope to make more sails in the near future.

Thanks!

[JimD]

I think you need Todd Bradshaw. These are questions he's answered a hundred times for us on this forum so hopefully he will again be generous with his time and expertise and come along to help you out. Have you considered a sail kit from Sailrite?

[Yeadon]

Seems like you'll need a touch of belly in it, versus it being inherently flat. And that's where my knowledge stops.

[smallyachtsailor]

Thanks Jim, I'll take a look at Sailrite, although I do derive much of my boating pleasure from doing it all myself.

I'm sure these are questions that have been asked many times before. I've been searching this forum, and elsewhere on the web for answers and will continue to try.

[Thorne]

Some very good lugsail info on Mik Storer's site. I second the idea of a kit from Sailrite. Haven't helmed a boat with a sail of this type, but all the literature and discussions seem to stress how critical it is to get (and keep) the leading edge **tight and flat**.

[Todd Bradshaw]

(1) Chinese junk sails are essentially a type of balance lug and were traditionally cut flat. Western-style, typical balanced lugs are not. Most traditional western lugs are vertically cut (though cross-cut paneling will also work fine) and shape is designed into the sail, both in terms of head and foot-round, and by broadseaming. They may or may not use luff round as an additional shaping tool, depending on size and who is building them. Typical sailmaker's luff round (cloth being forced into the middle of the sail as the luff is pulled tight and straight, creating draft) doesn't always work on lugs, especially small-ish ones. With no mast connected directly to the luff, there may not be enough force to pull the luff straight - and instead of creating draft, you just end up sailing around with a curved luff which is kind of loose and prone to flapping. For that reason, it is often a better idea to cut the luff dead straight (or even slightly hollow) and get your shape through broadseaming the upper and lower edges of the sail.



This is a partially completed lofting for a pair of balanced lugs. Ignore the outer, bigger one and let's concentrate on the inner smaller one. The curve of the head (top) side is a combination of some round added to create draft and also adding a bit of extra curve to allow for some yard bend when sailing. The foot is loose-footed (boomed, but not laced along the boom) and the curve is basically there just to give it a nice lower edge profile. The leech edge is hollowed slightly to prevent flapping. The luff is cut straight. It will also be well reinforced (five layers thick at a minimum) to take the rather high downhaul tensions that lugsails get. The red lines at the corners are where the corner patches will be, and are mostly just there to get a feel for the proportions. The two V-shaped lines at the top and bottom represent the beginnings of the broadseaming areas. Any panel seam that crosses one, will be gradually increased in overlap width from that spot to the edge of the sail. What may be a normal, 1/2" wide vertical panel seam in the middle of the sail will start to flare-out at both the top and bottom of the sail, once it gets to that spot. Formulas that tell you where to place these reference lines and how much you need to increase your seam overlaps don't really exist, so it's up to the sailmaker to have a feel for them from experience. Cross-cut lugs will also have broadseaming, though it is done in different areas to achieve similar finished shapes.

I'm really not trying to bury you in techno-mumbo-jumbo, but if you're going to design a balanced lug that works nicely, you need to know how to shape it, and that's not an easy task for somebody who has no experience doing it. This is where the Sailrite kit really starts to shine. The shape will already be designed into the sail. If you put the pieces together accurately, you can be assured that the shape will be good and the sail will work properly. You will still have plenty of work to do and will still feel like you made it yourself, but the result will almost certainly be a much better sail. It's always great to say "I did every bit of it myself" - but if it doesn't work very well, that's not so great.

(2&3) Yes, Dacron is what you want. The most economical Tanbark Dacron for an 85 sq. ft. balanced lug would be Challenge Sailcloth 54" wide Tanbark in 3.8 oz. weight. If you're planning on a lot of high-wind sailing at 85 sq. ft. you might also consider going up to the 5.53 oz. weight for more durability. Without actually measuring things, I'd estimate that you probably need 10-11 yards to build a lug that size. Retail price is probably going to be $22-$25 per yard, so it's a pretty serious investment. Toss in about $20 for seam basting tape, thread, some spur grommets or rings to hand sew, and the setters they need and pretty soon you're talking some fairly serious money. Without access to wholesale pricing (which you won't have) the materials alone will probably be in the $300-$350 range at a minimum (more if you have to buy grommet setters). That's probably getting fairly close to the kit price (where they sell you fabric at a discount along with excellent design work) so it's pretty hard to justify trying to do it all from scratch.

If you need a plan to work from, either from scratch or for a kit, this is one of the nicest I've found for balanced lugs. As is, it makes a 59 sq. ft. sail. To get 85 sq. ft. you would just need to multiply all the linear dimensions (edge lengths, diagonals, etc.) by 1.199. Ignore page 1. The sail dimensions are on page 3.

http://webpages.charter.net/tbradsha...s/!CLCSKER.PDF

The finished sail looks like this:

[smallyachtsailor]

Todd,

Thanks so much for the very thorough answer--everything I asked has been answered in detail. It does appear that you've answered these questions before. I do have enough sailmaking experience to understand all of your explanation, including "guesstimating" the broadseaming and all. I enjoy a challenge--half the fun of being out on the water is sailing a boat of your own making. Even after 40-some years of designing boats the best part is still learning more. Of course the way to be successful with something new is to learn everything you can about it first. Nonetheless I'll take a look at the Sailrite kits and see what they have to offer, however it sounds like they do all the fun parts...

Thanks again all--I appreciate the time you take to answer my questions. This forum is definitely a great resource.

[JayInOz]

You're not allowed to die Todd- ever JayInOz

[smallyachtsailor]

You're not allowed to die Todd- ever JayInOz

Seriously. At least write all this down first...or have you? Is there a book?

[StevenBauer]

Seriously. At least write all this down first...or have you? Is there a book?

There is indeed a book: http://www.woodenboatstore.com/product/325-110

[Todd Bradshaw]

I'm doing the best I can to avoid that Jay (although I do still have a couple bad habits left over from the rock and roll years).

Smallyacht sailor, if you want to try a scratchbuilt one, it might be easier to cross-cut it. The broadseaming would be more typical of what you might be able to read about and get guidelines for in sailmaking books, and would actually be pretty similar to broadseaming a Marconi, or even a lateen sail. Here is a generic cross-cut balanced lug.



The luff (A) would be cut straight and reinforced well. The loose foot (B) has some round added (typically maybe 2.5"- 4" or so) to yield a nice profile. Keep the curve fairly flat at the aft end to prevent flapping. The head (C) has some round added for draft and some more added for a yard bend allowance (deepest round about 45% aft). This amount will obviously depend on your yard's characteristics, but on something in the 85 sq.ft. range, the total might be in the 3" range, with an inch of it being for making draft and 2" for spar bend allowance. (D) The leech is hollowed about 1" per 10' of leech length to prevent leech flap. (F) - these represent two short, slight broadseams in a couple of panel seams about 18" long by about a 1/8" increase in seam overlap as you get to the leech edge. They help keep the leech firm as the sail ages.

The broadseam reference line is the curved orange line. Any seam that crosses this line will begin to be broadened as you head toward the luff. A typical, 1/2" wide, medium Dacron seam would have an overlap increase of about 1/2" per every 30" of broadseam length. This is normally done in a smooth taper with a slight flare (more dramatic overlap increase) at the final, luff end (yields a rounder entry angle for the sail - more forgiving of sail trimming errors). (G) is the tack seam (intersects the edge near the tack corner). It is the most important shaping seam on the sail and will usually get an increased broadening rate that may be as much as twice the normal amount (1" overlap increase per 30" of broadseam length).

The foot panel has been split at (H). This is not because we're running out of cloth, but because we want to add a vertical broadseam there to "cup" the foot a little bit. This is both for a little bit of the old "end plate effect" (helps keep air from sneaking around the bottom of the sail and robbing us of pressure) and also to help keep our rounded foot from flapping. So this vertical seam would start at the tack seam with our normal 1/2" seam width and start broadening immediately as it heads toward the foot, with a little bit of flare at the bottom. You could also broadseam the forward end of the panel seam at the head (near "C") to cup the head a little bit, but you probably won't need to. The tops of cross-cut sails generally need little or no broadseaming, and you don't want too much shape up there, other than what the wind puts in all by itself. Despite the fact that this is a lugsail, all this broadseaming is pretty typical for any cross-cut sail and it involves less guess work than a first attempt at a traditional, vertically-cut lug would require.

I used to love building modern, fancy radials from Kevlar, mylar, Technora and other exotic fibers and miss it from time to time. One of these days I'm going to build myself a Kevlar radial lugsail, just for fun. I'll have to convince Jeff at Sailrite to plot it for me as all the panel edges, which look straight on the plan, are actually carefully calculated curves, but it would be very cool. I'll pick some generic size around 65 sq. ft. and have it plotted on heavy pattern-maker's mylar. Then I can trace the pieces and make multiple copies out of any fabric I want.

As long as I never have to spend my life making cheap, white price-point sails for a living, all is good........

[smithb9]

That radial design would look pretty cool!

Todd, are there set dimensions for a balance lug sail, or can the shape vary? For instance, is it possible to have a slightly higher aspect ratio, with a higher peak? It seems like some of the yawl rig designs are fairly high peaked, but perhaps that's just the angle of the picture and/or the shape the sail takes with some wind in it?

[Todd Bradshaw]

Shape and aspect ratios seem to vary and I have never seen any sort of specific guidelines for what works best and what doesn't work so well. I suspect that there may be an upper limit to the yard's peak angle being effective, since part of what keeps the sail stable when tacking is the tail-heavy yard pulling upward on the luff. Peaking it up too high might limit that stability and cause it to wobble, but I can't say for sure. I suppose there could also be a limit to how far upward you can stretch the middle section, since it generally has no support other than the luff tension. Unless somebody decides to build a whole bunch of lugsails to try head-to-head on similar boats though, we may never know the true answers to the questions.

Did you see the mylar radial spritsails in Lagspiller's thread the other day on Oselver racing? That's the type of thing I want to do with a lug some time. You can get down to some really light cloth weights and still have strength if you reinforce them carefully. When I did the first set of sails for my Mini-12 I used 2.2 oz. hard racing Dacron and Mylar/Kevlar/Vectran Diax that weighed about three ounces and they were bomb-proof. I designed and lofted the main out on my kitchen floor at the time, without a computer though, which was a task I'm not interested in repeating.



I had Jeff plot out the main and jib for our Speedball from a roll of Dimension Polyant Technora (about 3 oz.) and it saved me a whole lot if really tedious figuring.


They're certainly not traditional, but they're fun to build.

[smithb9]

Thanks for your input Todd.

I was planning on starting exactly this thread at some point, was glad to see that someone else was in the same boat.

Nice sails too, pretty cool to be able to see all the broadseams in that first picture.

[AJZimm]

Todd,

Let me add my thanks to for the time you take to respond and for your clear explanations. It helps me to understand what I got from my sailmaker.

[Todd Bradshaw]

Those"patch-less" corners are pretty neat, but a real pain to lay out. In most cases, radial corners are built with a batch of short, straight-sided strips of fabric which you fan out like a poker hand and sew down on top of the sail - like the jib corner in the second photo. About 20 years ago, I decided to try integrating the corner patches into the actual sail panels, rather than cutting and adding new pieces on top. Each triangular sail panel was lofted out, and then a narrow, long, tapered triangular flap of extra fabric was added along one side before they were cut out. This flap overlaps neighboring panels when the panels get assembled and the closer you get to the corner, the more these overlaps overlap other overlaps. By the time you get to the actual corner where the clew ring is and you need good reinforcement, you have a buildup that's about nine layers thick - and the transition from one layer of cloth in the middle of the sail to nine layers at the corner to reinforce the ring is really smooth. I was kind of proud of that brainstorm and the broadseamed corners look really nice, though as mentioned, the layout process was a real bear.

[smallyachtsailor]

Thanks for your input Todd.

Nice sails too, pretty cool to be able to see all the broadseams in that first picture.

Ditto.

I kind of prefer the look of the vertical seams on a lugsail, although you are correct Todd, more people are familiar with cross-cut sails, as am I. However, scratchbuilding a lugsail will make a nice winter project for me, and I want to learn more. I'm also working on a 12-foot sail/paddle canoe (50-50) that I also want to make a lugsail for, although only about 30 sq. ft. in area. So I might as well get some practice in. And if I can find more room around the house (8 or 9 boats and counting...) I hope to build a few more small sailboats--which will all need sails of some sort.

Looks like I'll need room for one more book on my bookself--thanks Todd!

[SEAN H]

Todd,
Thank you for your great input to this forum. How important to the design is the rake of the luff, which you show at seven degrees? Was that done to use the existing mast step and keep the center of effort in the right place? Would a vertical luff be okay in a new design, or would you consider a seven degree rake about normal? Thank you for any input in advance.

[esingleman]

I ordered a sail kit for my standing lug rig boat (see avitar) from Sail-rite. It was about 25% the cost of having them made. The panels are computer cut to produce a fine looking airfoil when filled. My experience is that a boat that does not use a jib sail (as I have sailed my boat many times without the jib raised) does not point as well to windward, nor does it tack as easily. Therefore any loss of speed due to sail inefficiency or poor sail trimming on a lug rig will noticeably affect these aspects of sailing. If it were me, I would go the Sail-rite route and be confident in having a nicely designed airfoil in the end that will give you maximum performance.

BTW, my sails are eleven years old now and still look great and have kept their shape, and they are made of dacron.

[Gerarddm]

Brilliant, Todd. Thanks.

[James McMullen]

. . .My experience is that a boat that does not use a jib sail (as I have sailed my boat many times without the jib raised) does not point as well to windward, nor does it tack as easily.

Esingleman, I think you should be careful extrapolating from how well your sloop-rigged boat performs when it's got only part of its sail plan in action versus a how well a boat that is balanced and optimized for use without a jib in the first place can work. Not only would ten-thousand Lazer sailors disagree with your above statement, but I do too.

I do however totally agree with you that it is a very worthwhile investment to buy a correctly lofted kit from Sailrite.

[Todd Bradshaw]

Sean, The rake isn't critical, but it will primarily do two things. First, it may aid the boat's designer at times by moving the sail's center of effort aft a bit. This will sometimes make the layout of the centerboard position, the seating arrangement, mast partners location, etc. work a bit better and give the crew a more comfortable space to operate in. The other thing it will do comes into play when the boat is heeling a bit and the sail is out to one side (like it would be when sailing a broad reach or when running downwind). As the boom swings outboard with a raked mast, its aft end will move upward a bit (gets slightly higher above the water). On a plumb mast, for example, if we centerline our boom and its aft end happens to be 30" above the water, and then we ease the sail out to one side, the boom's aft end will still be 30" above the water. With the raked mast, our boom might be 30" above the water when centered, but when eased out to the side, the aft end might be 36" or better above the water.

As our boat heels over while sailing with the boom outboard, the amount of clearance between the boom's tail end and the surface of the water will diminish. The more you heel, the less clearance you have. At some point on some boats, you can actually get to the point where the sail's clew corner is skipping along on the surface (a Sunfish is an excellent example of this with that long lateen boom and plumb mast). When this happens, you can't ease the sail out any more - even if you want to, or even if you need to, to keep from rolling over. It just won't go out and will continue to plane along on the surface. If you can't use your weight to roll the boat back into a more upright heel angle, you may be in trouble. Raking the mast a bit will add a little more clearance between boom and water in this type of situation.

I'm sure there may also be some sort of high-tech, swept-wing theory that might come into play when we achieve mach 1 boat speed, but I'm also sure that I haven't got a clue what it might be. In most cases, balanced lugs are cut with the luff edge pretty much parallel to the mast, so if the mast is plumb, the luff will be, too and if the mast is raked, so is the sail's luff. I don't know if there is an ideal rake angle. I usually shoot for something in the 5-7 degree range, depending on what the boat's structure will allow. I suppose that too much rake might encourage an awful lot of mast bend from mainsheet tension, which in turn might hinder proper luff tension and performance, but it doesn't seem to be a problem with modest rake.

In a somewhat less critical vein, we can also consider cosmetics. On certain boats, a little bit of rake just looks better. I tell my customers that despite all the blood, sweat and tears that they put into building a beautiful boat, from 100 yards away the work I do will probably show up a lot more than the work they did. I think designers and sailmakers need to keep that in mind - because who would want to see ugly boats floating around all over the place? The modern fiberglass box-boats that litter the average marina have already pretty much got that area covered.

The lug profile that I build most often (in various sizes) is a profile that I "borrowed" from Iain Oughtred. I first saw it on a Ness Yawl and it just struck me as being the prettiest balanced lug profile that I had ever seen. It has the raked mast (and luff) and I saw no reason to mess with that as long as the boat owners I was building sails for could adapt their mast steps and partners to accomodate it. The tape loftings and the Skerry pictured in post #6 have that profile, as does the radial lug drawing. I believe the first one I built was for the Oughtred Elf built by Steven and Gavin Bauer. It just looked like the perfect sail for the job. I liked it enough, in fact, that I used Eric Michaels' photo of the boat on a CD cover. To my eye, for a traditional balanced lug that both works well and has a lovely profile, that Oughtred lug with the raked mast is very hard to beat.

[esingleman]

Esingleman, I think you should be careful extrapolating from how well your sloop-rigged boat performs when it's got only part of its sail plan in action versus a how well a boat that is balanced and optimized for use without a jib in the first place can work. Not only would ten-thousand Lazer sailors disagree with your above statement, but I do too.

Actually James, Joel White designed my boat to be used both with and without the jib sail, and sailing without the jib was an optional choice for this boat. Joel compensated for this by having an elongated hole in the seat where the mast passes through so the mast can be angled forward and locked in that position with a nice little wedge type piece. The forward angled mast moves the center of effort forward and back where it was when both main and jib are used therefore the helm response is the same.

Additionally, small yacht sailor was talking about a balanced lug rig, which is similar to my standing lug in that although very convenient to store and set up is never going to be as efficient as the high aspect ratio marconi laser sail which I guarantee points much better to windward. So my point is that with a lug rig, that is not very efficient to begin with, doesn't point as well to windward, and doesn't have jib to help it point better to windward, you probably don't want to introduce any more inefficiency by making an sail that is a close approximation to what it's supposed to look like. I didn't mean to imply that all boats will perform better with a triangular rag up front

Erick

[smallyachtsailor]

Do you think Joel White would mind if I stole that idea of an elongated mast hole and wedge to change the mast rake?

My main reason for choosing a lug rig was simplicity and a liking for traditional rigs. Besides, my boat is cat-rigged and I can neither move the mast back nor add a bowsprit easily to make room for a jib, so the jib/no jib argument for me is a moot point. If it was easy I'd probably put a jib on it. I also want to try a balanced lug so I gain some experience with it since I'll be putting one on my sailing canoe.

I have been thinking about the Sailrite kit option more, and may very well go that route the first time--it'll let me see how the lug sails are designed and put together. Then if I want I can try on my own after that, since half my interest in boats is learning design.

And I agree with Todd--Ian Oughtred's designs are inspiring...

[James McMullen]

Erick, I think that if you had added the area of the jib to the lugsail, especially in the length of the luff, you would have a more reliable comparison. I keep going on about this because I have not found Rowan to be at all deficient to windward compared to other boats of her size. . .and I must point out that I am no stranger to boats with jibs as three of the four sailboats I currently own sport headsails--one of them actually flying two at once. I do think that you can make those boats that are small enough as to not be wanting to put up with the compromises of a stayed rig work every bit as well without the complication of a jib.

Perhaps it has something to do with the low, square aspect of the Joel White rig? The rigs of proven lugger performers like Roxane, Romilly, Ran Tan, and (dare I say) Rowan are all much higher aspect with long, clean luffs. Of course the downside of this is a higher CG and longer spars to stow which may not have fit in with the design goals of your Joel White design.

[esingleman]

Well James, you are certainly entitled to your opinion and you experience with Rowan. However Isn't Rowan a Caledonia Yawl? If so, your mizzen would aid in windward performance I believe (never sailed a yawl myself). However, technically speaking, an air foil creates most of it's lift from the leading edge, making high aspect ratio sails like marconi rigs more efficient. I also remember reading the channeling affect of high velocity air passing between the jib and mainsail causes an increase in pressure drop also increasing the sails, lift. Therefore, I believe if I built a Caledonia hull with a stayed sloop rig of the same sail area as yours, I would beat you to the windward mark. In actuality I see this demonstrated every year at the Herreshoff Regatta where the Marconi rigged 12 1/2s always beat the gaff rigged boats to windward by so much, that they can't even catch up on the downwind leg where the gaffers have the advantage.

[IanHowick]

Todd, have you seen the cut of this balanced lusail on a Goat Island Skiff?

By Doyle Ploch, St Pete, Florida

Radial cut from the clew only, what do you think?

[Todd Bradshaw]

That's pretty neat. The only thing that I would wonder about would be having cloth panels which strike the luff on a bias at a whole bunch of differing angles, and how well that will hold up over time as the cloth stretches. The panel that intersects the throat at the luff will have about twice the amount of stretch that the foot panel will. We also get some bias stretch going on with a vertical or cross-cut, because in either case, the cloth weave hits the luff at an angle - but at least the thread lines for all the panels will be running the same direction and the stretch factor will be uniform along the entire luff. Having all those radial panel seams striking the luff would be pretty handy for shaping the entry angle though.

My main attraction to a radial would be to be able to run the warp yarns right up and down both the luff and leech for maximum stretch resistance and shape control, and then to see what, if any, performance improvement it might make (as well as how much excess cloth weight I could eliminate). You would pretty much have to use some sort of tri-radial or star-cut layout to accomplish that, which runs your assembly labor time up a fair amount.

I do like this idea though, of occasionally updating old traditional sail types with an infusion of modern technology. It's certainly not cosmetically "right" on every boat, but if being strictly traditional isn't a major focus of the effort, it brings in some interesting possibilities and in some cases, maybe a performance upgrade.

[smithb9]

Perhaps it has something to do with the low, square aspect of the Joel White rig? The rigs of proven lugger performers like Roxane, Romilly, Ran Tan, and (dare I say) Rowan are all much higher aspect with long, clean luffs. Of course the downside of this is a higher CG and longer spars to stow which may not have fit in with the design goals of your Joel White design.

James, this is something I've wondered about as well, partially because I like the aesthetics of the higher aspect lug rig better I think.

Looking at Iain's designs, it seems that the JII/Artic Tern is the only one that shows a high(er) aspect lug, where as the others (caledonia, ness, etc) seem to be more traditional shaped lower aspect. Does Rowan have the Artic Tern/JII rig, or is your sailplan something that you came up with on your own? Looking at the Artic Tern/JII, it seems that the luff is approx. equal length as the head with a high peak, compared to the CY where the peak is not as high, with luff approx 2/3L of head length.

[davlafont]

First, let me add my gratitude to Todd whose patient explanations and sharing of what might be considered valuable intellectual property is truly a public service. I'm close to launching my GIS with the Lug of my own making and I'm very grateful for Todd's postigs on the topic.

... I do have enough sailmaking experience to understand all of your explanation, including "guesstimating" the broadseaming and all. I enjoy a challenge--half the fun of being out on the water is sailing a boat of your own making...

Sounds like you might want to take a spin with the open-source freeware application SailCut: http://www.sailcut.com/Sailcut_CAD

I'll be the first to echo Todd's advice from other threads that using a computer to design your sail without a plotter to print out the full-size patterns is a little silly (I'm paraphrasing) when all you have to do is apply the fundamentals to your own lofting floor with string/tape/etc. I'll also be the first to admit that I don't always follow sound advice no matter how wise.

If you've settled on the dimensions you want (the GIS's lug is fairly high aspect compared to most), you can plug the details into SailCut and see the results in rotatable 3D, solid and wire-form. I enjoyed the tinkering enough to recommend you at least play with it.

[davlafont]

Todd, have you seen the cut of this balanced lusail on a Goat Island Skiff?

By Doyle Ploch, St Pete, Florida

Radial cut from the clew only, what do you think?

Ian, I'm glad you asked. I've been curious how others might react to what I think is the coolest GIS sail yet. But cool doesn't necessarily equate to smart. (But man, that thing looks sweet!)

[davlafont]

I do like this idea though, of occasionally updating old traditional sail types with an infusion of modern technology. It's certainly not cosmetically "right" on every boat, but if being strictly traditional isn't a major focus of the effort, it brings in some interesting possibilities and in some cases, maybe a performance upgrade.

This describes much of Michael Storer's approach to design. A nod to traditional aesthetics while keeping pace with modern technologies and techniques. He'll specify modern no-stretch line and use it to form a simple cow-hitch for example. But, Storer is also very keen to observe what works and what doesn't over time, an almost evolutionary approach to solutions. The GIS community needs Simon to put more time and nautical miles on that partial radial lug so we can see how she fares in the long run.

[IanHowick]

That's pretty neat. The only thing that I would wonder about would be having cloth panels which strike the luff on a bias at a whole bunch of differing angles, and how well that will hold up over time as the cloth stretches. The panel that intersects the throat at the luff will have about twice the amount of stretch that the foot panel will....

Thanks, Todd for your thoughts. I had thought similarly, wondered about the varying bias angles at the luff as you crank up downhaul tension, but it sure seems to set nicely.

One thing I noticed on my cross cut GIS lug, is with three sets of reef points, there are four sets of tack reinforcements along the luff, with the throat reinforcement as well, all these reinforcement patches overlap each other and mean there are a lot of layers of cloth all the way up the luff. Some integration of the original tack, reef tacks, and throat reinforcement and the necessary luff edge reinforcement on a lugsail would be worth thinking about.

I do like this idea though, of occasionally updating old traditional sail types with an infusion of modern technology. It's certainly not cosmetically "right" on every boat, but if being strictly traditional isn't a major focus of the effort, it brings in some interesting possibilities and in some cases, maybe a performance upgrade.

[smallyachtsailor]

First, let me add my gratitude to Todd whose patient explanations and sharing of what might be considered valuable intellectual property is truly a public service. I'm close to launching my GIS with the Lug of my own making and I'm very grateful for Todd's postigs on the topic.

Sounds like you might want to take a spin with the open-source freeware application SailCut: http://www.sailcut.com/Sailcut_CAD

I'll be the first to echo Todd's advice from other threads that using a computer to design your sail without a plotter to print out the full-size patterns is a little silly (I'm paraphrasing) when all you have to do is apply the fundamentals to your own lofting floor with string/tape/etc. I'll also be the first to admit that I don't always follow sound advice no matter how wise.

If you've settled on the dimensions you want (the GIS's lug is fairly high aspect compared to most), you can plug the details into SailCut and see the results in rotatable 3D, solid and wire-form. I enjoyed the tinkering enough to recommend you at least play with it.

Yes thanks for pointing that out. I've played around with Sailcut before, although I do not possess a huge plotter so its mainly an academic exercise.

I just ordered a copy of Todd's canoe rig book, looking forward to looking through it--although that can be dangerous. I should get this project finished before I add to my long list of boats I'd like to build.

[davlafont]

...although I do not possess a huge plotter so its mainly an academic exercise.

Not completely academic. It can be done by hand. I laid my sailcloth out on two nice sheets of 3/4" ply (excess from another project) with the edge of the cloth right at the edge of the panels. Using a drywall t-square and other metric rulers I plotted out the X and Y coordinates available from Sailcut. I'll repeat that it's not necessarily the preferred method, but in my case it suited my conditions. I have no space to loft out the full 105 sq ft GIS lug. But I had room in my basement to cut one panel at a time. Relying on the computer to develop the broad seam made it possible for me to sew my own sail at all.

[smallyachtsailor]

Not completely academic. It can be done by hand. I laid my sailcloth out on two nice sheets of 3/4" ply (excess from another project) with the edge of the cloth right at the edge of the panels. Using a drywall t-square and other metric rulers I plotted out the X and Y coordinates available from Sailcut. I'll repeat that it's not necessarily the preferred method, but in my case it suited my conditions. I have no space to loft out the full 105 sq ft GIS lug. But I had room in my basement to cut one panel at a time. Relying on the computer to develop the broad seam made it possible for me to sew my own sail at all.

Heh. Probably at the same time you were writing your response, I was pondering how I could use Sailcut's output myself, without a plotter. You've settled it. I'll use Sailcut and follow your path--since it's always safer to walk in someone's footprints through a minefield--presuming they don't end in a big hole...

I love it when a plan comes together. The cats are gonna love 'helping' me with this sail... Thanks Dave!

[Todd Bradshaw]

Back when I was dumber, I built a few sails, both computer-plotted radials and traditional cuts, that were bigger than the room I built them in. It was kind of strange to not even be able to see the sail until it was done and spread out on the lawn, but it worked. The plotted radials were fairly easy, building the radial sections and then finally joining all the sections together. The traditional ones were drawn out using the same 1990 basic Apple drawing program and first generation PowerMac that I still draw everything on, and then the panel measurements were taken on the screen and transferred to the roll of cloth with a measuring tape with no full-sized lofting done. For an occasional sail or two, it can be done, but it's pretty tedious and awfully time consuming to do as a business.

[brucemoffatt]

I hope nobody minds me bumping this thread. I got a quote for a balance lug sail today, around 100 sq ft, loose footed (for a Scamp). After looking at the boat plans and questioning how I might be intending to use the boat the sail designer proposed that it should be made with vertical panels. I remembered there was this thread and sure enough Todd suggests similar in general terms early on ^^ up there.

So my question is, what benefits might vertical panels add to a sail like this? I guess even from a novice like me I can see there's the situation of not stretching seams over time, but I don't really understand even after reading Todd's posts above how you would get an airfoil shaped lug sail with vertical panels. I assume vertical panels means parallel to the leach rather than luff.

I have time to learn a bit more so if everyone isn't exhausted by the discussion to date, any comments?

Bruce

[Todd Bradshaw]

A vertically cut balanced lug gets an airfoil shape the same way a cross-cut balanced lugsail would, by broadseaming the panel seams - only in different places, since the seams will be in different places. Cross-cutting is at its best on sails with luff round and with most of their broadseaming along the seams striking the luff. The fact that the luff is attached to the mast forces the extra fabric of the round into the sail and the broadseams help to position the excess fabric into the proper place to make draft. On a balanced lug, building in luff round is often not very effective. There is no mast to force the round into a straight line and force draft-creating fabric into the sail. Plus, the luff should be heavily reinforced to handle high downhaul tension and that area is rather stiff. On even small lugs, the luffs I build are at least five layers thick everywhere. Chances are that rather than being able to pull luff round straight and create draft, what you'll actually get is a curved luff that just flaps or tends to wobble back and forth. Not good. So on a cross-cut balanced lug, your prime broadseam areas (seams striking the luff) may not be on an edge where they can do much good. If you have some foot round, you may not have enough (or any) seams striking the foot to properly shape the foot of the sail. In that case, you have to split the foot panel (below the tack seam) into multiple sections and install some vertical broadseams to give it shape. Otherwise, your foot round will just be a flap hanging down, and it will actually flap in use.

The vertically-cut balanced lug can be cut with either a straight luff or even a slightly hollowed luff if it's a long one - a luff that will pull straight and stay straight and more firm and stable in use with decent downhaul tension. Broadseaming is then done on the multiple seams striking the head and foot edges, giving the sail its shape without needing to monkey around with the luff or with luff round. It just works better and the airfoil shape is just as good or better.

Historically, vertically cut sails (in general) fell out of favor when somebody figured out that cross-cutting presented a smoother, less-wash-boardy surface for the wind to flow over, which was faster. That was in the days of cotton sails though, and the panel seams (french-feld, four layers, double stitched) were four times less stretchy than the fabric right next to the seam. This is what caused the wash-board effect. With modern, low-stretch resin-stabilized Dacron, this is not the case, and you don't generally see much fabric stretch going on at all, so on something like a lug or spritsail you can use a vertical cut without paying that particular penalty.

The ideal "best" lugsails would probably be radial-cuts using warp-oriented fabrics, but they would be rather untraditional and I don't know whether anybody has worked up the software to plot them. You could use lighter cloth in those areas where stresses were less for less weight aloft, heavier cloth in high-stress areas, and aim the yarns in the directions that the stresses in particular areas were coming from.

[Wooden Boat Fittings]

Todd (and anyone else) -- what do you see as the advantages of a balanced lug over a standing lug (which is far and away my preference)?

Mike

[wtarzia]

I thought the main issues between balanced and standing are (1) to vang or not to vang by using the sail alone (balanced luig's vanging properties; but you can vang a standing lug if wanted of course -- a simplicity vs.complexity issue?), and (2) how much can the sailor tolerate looking at that forward-of-mast sail area aback on the "bad tack" of the balanced lug? (I have seen and felt little difference here on my standing lug cat-ketch: i.e., the various tensions in the system seemed to have prevented any significant leading-edge-aback-the-mast on my small standing lugs; however, the LE of my mizzen lug sometimes vibrated annoyingly no matter how hard I hauled the downhaul. The LE has some round to it; maybe too much? These two lugs are the Wooden Boat Store 54 and 37 sf.).

And related to the previous post: (I hope I have not asked this before, but I've asked many questions over the years....), would the sail cut as Todd recommended above be not-good if the same sail were used as a standing lug?

Personal Background to the question -- I have a balanced lug from a Payson-Bolger Windsprint (~114 sq. ft). I've used it both as a balanced and as a standing lug a couple of times. And yes, this is because, though people tell me I won't tell the difference between the bad and good tack on the balanced lug with the LE aback, I imagined I did, and tolerating the ugliness of a nearly two foot panel of sail aback was driving me crazy. So I tried the sail as a standing lug too. No, in my two or three trials I saw no performance difference though I was wondering about additional sail-twist when I shifted to the standing lug (lost vanging effect of the BL); however, I had not much noticed bad twist problems with lugs. --Wade

[Todd Bradshaw]

Todd (and anyone else) -- what do you see as the advantages of a balanced lug over a standing lug (which is far and away my preference)?

In many ways, I actually see the standing lug as having the adantage over the balanced lug. It can be used boomless, boomed or with a pole for downwind only. It is a more direct path from something very solid (the mast or gooseneck area) where the tack is fixed, to the forward end of the yard, which makes it a bit easier to generate really good luff tension. It also has more adjustability of upper sail twist. People tend to think that sail twist is a bad thing. It can be when excessive, but being able to induce twist when you want it can also be a very good thing. It is essentially your first reef, as you let the top of the sail twist to leeward, spilling excess wind, dumping excess power and reducing heeling force just by using the mainsheet. It will also act like a shock absorber when sudden gusts strike. The balanced lug tends to be more "fixed". You may get a bit of twist, but you can't induce a similar amount and you have less ability to fine tune it. With just about any sail, if you aren't getting maybe seven to ten degrees of twist up top, your sail is probably overtrimmed, because the wind up high tends to be faster, which tends to shift the aparent wind up there a bit. If you happen to be one of those people who is seriously interested in tweaking your sails for maximum performance, the standing lug may be more interesting for you to sail. On the other hand, sailing the balanced lug is probably a bit less complex and can still give excellent performance.

Wade, there usually isn't an awful lot of difference in the way the two types are cut. Whether the balanced lug could be rigged as a standing lug sort of depends on its particular profile shape, but in many cases all it would do is peak up the yard and the tail end of the boom a bit more than normal. The luff coming back at you or wobbling back and forth on a lug is almost always either a matter of inadequate luff tension or luff round that can't be pulled straight (if you ask me, it shouldn't be used in the first place on lugsails for that reason).

[Bill Perkins]

Todd ;I intended to ask you the same question ; and I also thank you for your generous posts over the years .

I'm going to try a lugsail on my Ducker ,and am leaning toward the standing lug .I've got a small spritsail that's very handy ,but I want to set more sail .It will have to reef and/or come down quickly though .

I want to try the option of the balance reef .The weight of the yard is going to be significant on my tender boat and I like the idea of stabilizing the yard and lowering it right down with the deepest reef.

I've been reading Conor O'Brian's "Seaboats, oars and sails "; a good old oar and sail book available from The Press at Toad Hall. O'Brian details the balance reef as rigged on the Loch Fyne skiff in the West of Scotland when he was writing .I 'll have no jib and I'll use a boom but the rig has 2 bits of gear I want to try : a jackstay and a reefing halyard .The last bit need not be touched when making the normal reefs.

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The main halyard is loosed to bring the heel of the yard down to the tack of the sail where it’s lashed like the other balance reefs shown ,but tightening the down haul or reef halyard then fixes the yard more rigidly in place .It looks like the reefing halyard ,though still untouched ,helps control the yard during lowering . When the yard needs to come completely down ,the reefing halyard is slacked off ,lowering the yard under good control .

O’Brian preferred the mast head sheave on smallish standing lugsails set for and aft . When faced with a long tack on the “off” side he then had the option of luffing the sail and simply forcing the heel of the yard down and around to the lee side of the mast .

Anyway ; I’m going to try it all. O’Brian has lots to say about other small boat rigs as well. I recommend the book to the sail and oar crowd.

[wtarzia]

An interesting reefing method. I guess it sets a little like a fully reefed Gunter rig, except that the reefing halyard seems like an improvement over the Gunter method? -- Wade

[James McMullen]

Conor O'Brian is awesome, and when it comes to sail and oar boats there's really nothing new under the sun. . .except for maybe epoxy, dacron sailcloth, low-stretch spectra, dyneema or double-braided polyester ropes, delrin, WLPU paint, carbon fiber, CNC machining, the modern sciences of Hydrodynamics and Aerodynamics, stainless steel, Monel, titanium, nylon. . . . .
Just like MacGregor or Slocum, Conor is still worth a good read, though.

I prefer the balance lug for its all-around qualities and ease of handling for a single-handed sail and oar boat. If I were in a larger, wider, and ballasted boat then I might be tempted more by the standing lug or a dipping lug, or with screwing around with the complications of headsails, but the user-friendliness and especially the lightning-quick, on-the-water setting, striking and reefing of the balance lug is unparalleled. And a modern, computer-lofted Dacron, vertically-cut lug sail is a beautiful, beautiful thing when it's tweaked right. Even though it's really not, it looks all olde-fashionedy, so it's even more salt in their wounds when you beat a modern cruising sloop sailing to windward in your lapstrake open rowboat. I love that!

[Jamie Orr]

The latest Watercraft Magazine shows a Chebacco on the cover, unusual in that its rigged with a lugsail. It's called Lizzy Bend aand is owned by Jan Doddema in Holland. I have a couple of pictures from Jan showing Lizzy Bend under sail with the lug (I'll post these once I've gone back and read Thorne's instructions!) Interestingly, Jan has had the sail recut to gaff, mostly because of the difficulty of controlling it, especially when lowering.

Cheers,

Jamie

[James McMullen]

Well I'd certainly agree that for a large boat with auxiliary power that doesn't set or strike its mast underweigh, a gaff rig with topping lift, gaff and boom jaws or goosenecks, and sail lacing or hoops would certainly controll its sail more predictably. These things don't always scale up or down all that well; what's appropriate for a small boat ain't necessarily what's right for a bigger one and vice versa.

[Wooden Boat Fittings]

Thanks guys. That confirms me in my order of preference for lug sails -- standing, gunter, balanced, and dipping a long last.

Mike

[Todd Bradshaw]

And a modern, computer-lofted Dacron, vertically-cut lug sail is a beautiful, beautiful thing when it's tweaked right.

Who needs a computer? You just need a real sailmaker.

[Yeadon]

The latest Watercraft Magazine shows a Chebacco on the cover, unusual in that its rigged with a lugsail. It's called Lizzy Bend aand is owned by Jan Doddema in Holland. I have a couple of pictures from Jan showing Lizzy Bend under sail with the lug (I'll post these once I've gone back and read Thorne's instructions!) Interestingly, Jan has had the sail recut to gaff, mostly because of the difficulty of controlling it, especially when lowering.

Cheers,

Jamie

Looking forward to seeing your photos.