Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(15 November 2014) This essay discusses rigging lugsails. The 1 December issue will be about sail area math.
THE BOOK IS OUT!
BOATBUILDING FOR BEGINNERS (AND BEYOND)is out now, written by me and edited by Garth Battista of Breakaway Books. You might find it at your bookstore. If not check it out at the....
ON LINE CATALOG OF MY PLANS...
...which can now be found at Duckworks Magazine. You order with a shopping cart set up and pay with credit cards or by Paypal. Then Duckworks sends me an email about the order and then I send the plans right from me to you.
Brian Walker's Veep14 is stretched a bit, with spray rails added. Nice boat and nice smiles.
118 E Randall,
Lebanon, IL 62254
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Rigging A Lugsail
This applies to any sort of sail rig. For proper sailing the sail rig forces need to balance around the hull forces.
Look closely at Figure1 and see that the center of the sail area is placed right above the center of the leeboard's area. For boats like mine with shallow underbodies and deep narrow boards this is the way it has to be. You can't tinker very much with this if at all.
Here is what happens. In general you can think of the force of the wind as a giant finger pushing at the sail's center. Opposing that force is a giant finger pointing the other way at the center of the leeboard. The hull tends to rotate about that deep narrow board. So if those two forces are in vertical line the boat will not try to rotate and will in general maintain its heading.
If the center of sail area is moved aft of the leeboard, the boat will rotate into the wind if left on its own. To keep the boat on course the skipper needs to tug on the tiller as shown in the top of Figure 2. This is called "weather helm". Weather helm reduces the load on the leeboard and should result in a faster boat. If the skipper falls overboard the boat should rotate into the wind and stall and with luck wait for the skipper. A light weather helm is considered to be ideal.
Now take the case of the builder who modifies the rig so that the sail area centers forward of the leeboard. This might be by changing to a rig style with a jib, or perhaps by relocating the mast forward. Now the two opposing giant fingers on sail and leeboard are not in a vertical line and the boat will want to rotate around the leeboard bow going downwind. To hold the bow on course the skipper must correct by pushing the tiller as in the bottom of Figure 2. This is called "lee helm". Lee helm will increase the reaction load on the leeboard. If the skipper falls overboard the boat will turn downwind and take off without him. Lee helm is usually not considered to be good.
So the way I like to approach it is to keep the center of the sail area directly above the aft half of the leeboard. You might find lots of variations on the rules that hope to provide proper helm feel. Try them if you wish. But keep in mind that if you build the boat and it has lee helm, you need to move the sail area aft. If you have excessive weather helm, the sail area needs to be moved forward.
NOW, BACK TO THE RIGGING DETAILS.....
TYING ON THE SAIL...
I greatly prefer individual ties through the grommets although lacing looks neat. But the individual ties allow for last ditch sail shaping. If you think you needed more round in the head of the sail for example, you could make the ties in the center of the yard tighter than those on the ends. Also, a failure of a tie or two is of little consequence where a failure of a lacing line will be total.
One important note. The ties in the corners take most of the load. They should be tied as shown in the figure in two directions.
Let's look at the sail and halyard attachment in Figure 1:
As you see, the balanced lug sail pivots around the mast. I guess all sails do. But the balanced lug has the mast running through its middle somewhere, as do other Lugsails, junk sails and lateens. While the mast may interfere somewhat with the aerodynamics of the sail, great benefit is gained in proper "balance" of the sail areas that are in front of the mast. In particular if things are properly placed, the sail will twist less than similar sails that use the mast as a leading edge. As a result the lug is a low tech sail that can be more efficient to windward than you might expect.
One trick to rigging these efficiently is to get the "balance" correct. By my experience the yard should be hoisted about 40% aft on the yard. If you hoist farther forward than that you will get harmful sail twist when sailing to windward. Hoisting too far aft can make the sail uncontrollable. I have often seen in the older literature the advice to hoist at 33% aft. That will work OK but it has been my experience that all the stretches and sags in the system conspire to pull the sail aft with respect to the mast. So if you tie the halyard to the yard at 40%, in use the sail swings aft very close to that 33% value.
(You see the designer has little choice of mast placement once the sail has been chosen. The leeboard can only go at the hulls widest beam. The sail area must center right above it. The mast must cross the yard at a certain point. )
We need to rig the halyard so the sail stays near that 40% position by binding it somehow to the mast. This is especially important while reefed or while in rough water that will force the yard to pump back and forth on the mast. I know of three suggestions.
First for small simple boats that won't be reefed the best solution is to run the halyard through a simple hole in the top of the mast, tie it to the 40% position on the yard, and hoist solidly to the top of the mast. There must be a small amount of slack at the masthead of course to allow the yard to swing but that will appear automatically when you tension the sail with the tack line.
Second you can try the tightening noose system shown in Figure 3. Here the halyard runs in a loose loop around the mast before going to the masthead. It will stay loose until the yard is hauled up all the way. Then additional tension in the halyard constricts the noose (until it hits the stopper knot) and secures the yard to the mast. You will need rollers on the noose to keep the halyard from binding on the mast. I have a feeling that this is the most reliable system.
Third method works well with round and slippery masts. A loose slippery ring is simply dropped over the halyard and mast. I use this system on my Piccup Pram using a section of large PVC pipe as a ring.
THE TACK LINE....
Figure 5 shows the tack arrangement I prefer. As with the yard, the boom must be secured to the mast to prevent pumping in rough water. The actual location of the tack on the yard is not too important. In fact if it were at the very front of the boom you would have a standing lug. The standing lug is probably easier to rig and reef than the balanced lug but in my experience lacks the great manners of the balanced lug in sailing downwind.
The boom has a small cleat on it with a lanyard that wraps around the mast to locate the boom fore and aft. That loop should be fairly loose to allow easy up and down motion of the boom. This loop needs to be set up before the yard is hoisted to prevent the sail from blowing around and making a spectacular and dangerous kite during hoisting.
The actual tack line I prefer is a simple line that runs from the mast step over the boom and down to a cleat at the step. So with the boom loop attached, the yard is hoisted, then the tack line is passed over the boom, pulled very very tight, and cleated. In effect you have now a two to one tackle. All sail tensioning is done with the short and handy tack line and not with the halyard. On my Piccup I run the tack line through a cam cleat to allow for quick adjustment although I don't consider that to be as secure as the good old jamb cleat. In my opinion the tack should always secure to the hull and not to the mast. Securing the tack to the hull will secure the entire mast and rig to the hull in event of a capsize.
Here is some advice about how much to tension the tack line. It varies with wind strength. Look at the sail as you do it. See Figure 6. As you tension the sail with the force of the wind in the sail, stress folds called girts will appear in the sail. If the girt runs from throat to clew you need more tension. If the girt runs from head to tack you either have it right or can reduce the tension. A perfect setting will have no girts. Usually at the initial setup I put in a good girt from peak to tack. Then I watch it while sailing to see if that girt disappears. Then when convenient I trim as required. Remember that changing sailing conditions will change the tension requirements.
Nothing fancy needed here. Almost anything will work. Because the sail is balance already to a great degree the sheet forces are less than with other sail types. Because the tack is pulling down in the middle of the boom, the boom has less tendency to lift so downward pull of the sheet on the boom is of less importance. The location and lead directions of the sheet are of little importance also. It's another advantage of the balanced boom. By the was, if the boom is omitted to make the sail boomless, the sheet location is very critical and its needs change all the time. I think the boom is a great invention! The boom on a balanced lug can be quite light and still work.
Watch the leading edge of the sail for luffing, as with about any sail. You should be able to tack through about 100 degrees effectively, although if you are really interested in getting somewhere you might sail it more freely, say up to 120 degrees between tacks, especially if the wind is unsteady. While reaching or running a balanced lug sail, even a cheap polytarp one, will keep up with any conventional sail.
Also it should be mentioned that one of the most effective ways to trim the boat, helm-wise, is to rake the mast as required to move the sail are fore or aft. You can see that a small amount of rake will move the mast head quite a bit and the entire sail will go with the masthead. Old time boats had adjustable mast steps or partners. On my designs you can usually shim the mast partner on the bulkhead. It's one place where tinkering pays off. Making a mast a bit longer than shown on the plans is also almost always a good idea as it allows for this tinkering not to mention real life stretch of the rigging.
CABIN SAILBOAT, 25' X 6', 900 POUNDS EMPTY
About 15 years ago I built a Payson Canoe and used it for several years before selling it. I replaced it about 10 years ago with my Toto double paddle canoe. Toto has the same multichine cross section as the Payson Canoe but I tried for a long lean bow which would be better in rough water and more foregiving of bow down trim. I still have that Toto, unchanged in any way since new, and still use it all summer. Amanda Johnson demonstrates:
The Toto shape worked so well that I used it in other designs like Roar2 and RB42. I tried it also in a sailing boat, the 20' Frolic2 (the original Frolic was narrower, more of a rowboat than a sailboat). Frolic2 was unballasted with a small cuddy and I hoped it would be a good daysailer and one man camping boat.
Bill Moffitt had built my Woobo design and funded a 20% enlargement of Frolic2 that would have a cabin, water ballast, and a yawl rig for cruising near the Gulf Coast.
The 20% enlargement idea went very well except that I had to deepen the hull more than that to give some serious headroom in the cabin, but it doesn't have standing headroom. Great empasis was placed on ease of use and rigging. The main mast is short and stepped in a tabernacle. There is a draining anchor well in the bow, a small storage segment under the front deck. The mast tabernacle is bolted to the bulkhead that forms the front of the sleeping cabin. There is a utility room aft of the sleeping room. Water ballast tanks are under the bunks and in the sides of the utility room floor, about 600 pounds of ballast as I recall. Aft of the cabin is the self draining raised cockpit with storage volume under the deck. Finally there is a self draining motor well across the stern. Construction is taped seam plywood.
Bill couldn't start his Caprice right away but Chuck Leinweber of Duckworksmagazine gave it a try. He has the room and tools and smarts to tackle a project like this with no hesitation. There weren't many changes from the plans that I know of, the main one being adding a conventional footwell to the aft deck which is designed to have a hatch type of foot well as with the Bolger Micro.
Chuck trailered his Caprice up from Texas to our Midwest Messabout this June and I had a chance to go over it, sail it for a couple of hours, and watch it sail from other boats. Wonderful!
Chuck tells me it takes less than 15 minutes to rig the boat to as you see here. As shown the boat has its ballast so you see it beaches very well indeed. I asked about the ballast. He can flood the tanks without power, just open the access plate, reach in and pull the fill plug and let the water rush in. Since the tops of the tanks are about even with the normal waterline he has to move his weight around to keep the tank depressed long enough to completely fill. Then you reach into the filled tank, replace the plug in the bottom, and then replace the access plate in the top. There are two tanks to fill.
Are the ballast tanks worth the building effort? On a multichine hull like this the tops of the tanks form flats that give places for bunks and storage so that is good. When full the boat should have a very good range of stabiltiy. Chuck's boat has never been in rough going as I'm writing this so the effect of the ballast remains to be proven. It has been capsized in a practice but the ballast tanks were empty and the boat was empty with no crew, etc.. But the ballast is a success from the standpoint that Chuck is able to tow his Caprice behind a four cylinder pickup truck. My idea was to pull the boat up the ramp and drain the tanks afterward by simply pulling the drains plugs. But Chuck has found it best by far to empty the tanks before recovering the boat at the ramp. So he uses a bilge pump in each tank to pump them empty. I'd be worried about water ballast tanks on a wooden boat from a rot standpoint and would be careful to open all the plugs and access panels when the boat is stored.
(I should add that I think an empty Caprice will weigh about 900 pounds based on the plywood sheet count (eight sheets of 1/4", nine sheets of 3/8" , five sheets of 1/2" and one sheet of 3/4"). But any boat like this can hold an awful lot of gear and junk.)
Caprice has the tabernacle setup that I first saw on Karl James' sharpie. The mainsail is 190 square feet, balanced lug. The mast is fairly short, stowing within the length of the boat when lowered. Chuck demonstrated putting up the mast, maybe a 15 second operation. I've been drawing these for a while on different boats but this is the first one I know of to get built and used. I'm greatly relieved that is all works so well. Before you decide to tack a tabernacle like this onto your boat, be advised that the tabernacle posts go clear to the hull bottom with big bolts all around a beefy bulkhead.
I thought Caprice sailed very well in the light winds we had that weekend. Tacked very smoothly through 90 to 100 degrees which is all you can ever get with a low tech rig. Very smooth and quiet compared to the sharpies I'm used to. It didn't seem at all sensitive to fore-aft trim. In the light winds it went 5 knots on the GPS which is certainly fast for the conditions.
Well, all in all I thought Caprice was everything I was hoping for.. Plans are $45.
Some of you may know that in addition to the one buck catalog which now contains 20 "done" boats, I offer another catalog of 20 unbuilt prototypes. The buck catalog has on its last page a list and brief description of the boats currently in the Catalog of Prototypes. That catalog also contains some articles that I wrote for Messing About In Boats and Boatbuilder magazines. The Catalog of Prototypes costs $3. The both together amount to 50 pages for $4, an offer you may have seen in Woodenboat ads. Payment must be in US funds. The banks here won't accept anything else. (I've got a little stash of foreign currency that I can admire but not spend.) I'm way too small for credit cards.
I think David Hahn's Out West Picara is the winner of the Picara race. Shown here on its first sail except there was no wind. Hopefully more later. (Not sure if a polytarp sail is suitable for a boat this heavy.
Here is a Musicbox2 out West.
This is Ted Arkey's Jukebox2 down in Sydney. Shown with the "ketchooner" rig, featuring his own polytarp sails, that is shown on the plans. Should have a sailing report soon.
And the Vole in New York is Garth Battista's of www.breakawaybooks.com, printer of my book and Max's old outboard book and many other fine sports books. Beautiful job! Garth is using a small lug rig for sail, not the sharpie sprit sail shown on the plans, so I will continue to carry the design as a prototype boat. But he has used it extensively on his Bahamas trip towed behind his Cormorant. Sort of like having a compact car towed behind an RV.
And a Deansbox seen in Texas:
Another prototype Twister is well along:
And the first D'arcy Bryn is to the point the builder can sit and relax in it and imagine boating. You can follow the builder's progress at http://moffitt1.wordpress.com/ ....
The first Jukebox3 is on the (cold) water. The mast is a bit too short - always make your mast too long. A bit more testing will be nice...
AN INDEX OF PAST ISSUES
THE WAY BACK ISSUES RETURN!
MANY THANKS TO CANADIAN READER GAETAN JETTE WHO NOT ONLY SAVED THEM FROM THE 1997 BEGINNING BUT ALSO PUT TOGETHER AN EXCELLENT INDEX PAGE TO SORT THEM OUT....
THE WAY BACK ISSUES
1dec13, Stretched Stability, Ladybug
15dec13, Trailering, Sportdory
1jan14, Cartopping, OliveOyl
15jan14, Width/Stability, HC Skiff
1feb14, Hiking, Shanteuse
15feb14, Dory Stability, IMB
1mar14, Scram Capsize, Scrampram
15mar14, Bulkhead Bevels, Frolic2
1apr14, Capsize Lessons, RiverRunner
15apr14, AF3 Capsize, Sneakerbox
1may14, Paper Capsize, Blobster
15may14, Prismatic Coefficient, Roar2
1Jun14, Roar2 Repair, Piragua
15jun14, Rend Lake 2014, Toto
1jul14, Mast Tabernacles, Musicbox3
15jul14, Sandell Tabernacle, Mikesboat
1aug14, Taped Seams, Cormorant
15aug14, Plywood Butt Joints, Paulsboat
1sep14, Rowing 1, Vireo
15sep14, Rowing 2, Philsboat
1oct14, Guessing Weight, Larsboat
15oct14, SailOK2014, Jonsboat
1nov14, Chine Runners, Piccup Pram
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
JB Builds AF4
JB Builds Sportdory
Puddle Duck Website
Brian builds Roar2
Herb builds AF3
Herb builds RB42
Barry Builds Toto
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