Jim Michalak's Boat Designs
1024 Merrill St, Lebanon, IL 62254
A page of boat designs and essays.
(15 July 2023) We rig a lugsail. The 1 August issue is about "horse power".
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.
ALSO...In addition to the Duckworks downloads I also now have access to a large format inkjet printer which is making very nice full sized prints on paper. So I can return to what I started 30 years ago, you order direct from me by snail mail using the address above only with cash or check in US funds with the prices shown on this website, and I mail you full sized 2'x 3' paper prints. The price includes first class mail to US and Canada.
A very pretty new Piccup Pram awaits its sail rig, shown at St. Andrews Bay on the Florida panhandle. Finely built by Geoffrey Adams.
1024 Merrill St,
Lebanon, IL 62254
Send $1 for info on 20 boats.
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 way, 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 area 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.
FROLIC2, CUDDY MULTI SKIFF, 20' X 5', 400 POUNDS EMPTY
The photos show the prototype Frolic2 built by Larry Martin of Coos Bay, Oregon. Larry built the boat quite quickly this past winter including sewing the sail to the instructions given in the plans. He reported sailing it for the first time on a ripping day with an occasional 2' wave. I always advise testing a new boat in mild weather, especially a new design, but Larry got away with it. Looking at his photos, the neat work, and simple efficient rigging suggests to me that Larry has been sailing small boats a long time.
Frolic2 has a small cabin, probably only for one to sleep in because the multichines that make the boat good in rough water also rob you of floor space. To say it another way, the nice big floor space of a flat bottomed sharpie is what pounds in rough water and makes you uncomfortable. But Frolic2 has a 6' long cockpit so someone could sleep there too. There is bench seating. The cabin top has a slot top down the center and you can stroll right through the cabin standing upright in good weather and out the front bulkhead to the beach. The mast is offset to one side so you will need not have to step around it. Phil Bolger showed us how to do this about 15 years ago and it works. But Larry went conventional with his boat, mounting the mast on centerline and decking in the front of the cabin. On a slot top cabin you use a simple snap on tarp to cover the slot in rain or cold or bugs.
Frolic2 was designed for rough water, long and lean, especially in the bow, and with multiple chines. She's really a takeoff of my Toto canoe in shape. Larry omitted the motor well you see in the lines, and the oarlocks too (The wind must blow just right all the time in Oregon?) but I intended this to be a multi skiff sort of boat with rowing and motoring abilities. You can't row a boat of this size in any wind or waves but in a calm you can travel far if you have patience. I didn't fool around with a gadget motor mount - I put the motor well right in the middle and offset the rudder instead of the other way around. This worked out very well on the high powered Petesboat. We'll see how it goes on a narrow boat because the second prototype is getting the blueprint well as you see in the photo below of the Colorado Frolic2 still being built. You need little power on a boat like this, 2 or 3 hp is more than enough.
The lug rig is for quick easy stowing, rowing, and towing. (The blueprint sail is actually the same size and shape as that of a Bolger Windsprint, a boat which weighs maybe a third as much as Frolic2 and is much narrower. But I think the Windsprint might be over sparred for its size and weight.) Larry reports the rig is about right for the boat, sailing fine with a reef in and three adults on a windy day. The lug sail can be closer winded reefed than when full, perhaps because the sail is then shorter and the yard better controlled (less sail twist). For that matter a sharpie sprit sail the same size as the lug might be smarter in rough water conditions if you can live with the long mast. Switching rigs won't be hard. The mast can be relocated almost anywhere in the slot top without altering the hull to any degree. You just need extra partner and step fittings.
Update, 2006. Jeff Blunk's Colorado Frolic2 eventually found its way to Illinois and then to our Rend Lake Messabout in the hands of Richard Harris. We had a chance to try it out and I was quite pleased. It was fast and powerful. At one point with three men on board, with Max at the tiller, I went forward to tweak the sail which took a couple of minutes with me staring up at the sail. That done I looked back and saw that we were really rolling along.
And Gary Blankenship's Frolic2 completed the Everglades 300 mile challenge with him reporting sailing for hours at 7 knots or more. Last count he completed five of the challenges with a 4th overall in 2007 and 7th in 2012. Here is Gary's Frolic2:
Construction is with taped seams from eleven sheets of 1/4" plywood and two sheets of 1/2" plywood.
Plans for Frolic2 are $35.
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.
We have a Picara finished by Ken Giles, past Mayfly16 master, and into its trials. The hull was built by Vincent Lavender in Massachusetts. There have been other Picaras finished in the past but I never got a sailing report for them...
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:
A brave soul has started a Robbsboat. He has a builder's blog at http://tomsrobbsboat.blogspot.com. (OOPS! He found a mistake in the side bevels of bulkhead5, says 20 degrees but should be 10 degrees.) This boat has been sailed and is being tested. He has found the sail area a bit much for his area and is putting in serious reef points.
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
1aug22, Horsepower, Oracle
15aug22, Sharpie Sprit Sails, Cormorant
1sep22, Measuring Prop Thrust, OliveOyl
15sep22, Leeboard Issues, Philsboat
1oct22, Prismatic Coefficient, Larsboat
15oct22, Figuring Displacement, Jonsboat
1nov22, Lugsail Jiffy Reef, Mayfly14
15nov22, Sharpie Reefing, Piccup Pram
1dec22, Making Oars, Batto
15dec22, Taped Seams, Sportdory
1jan23, Rowboat Setup, Normsboat
15jan23, Sail Area Math, Robote
1feb23, Bulkhead Bevels, Toto
15feb23, Trailering Boats, IMB
1mar23, Small Boat Rudders, AF4B
15mar23, Making Sink Weights, Scram Pram
1apr23, Sailrig Spars, RiverRunner
15apr23, Water Ballast, Mayfly16
1may23, AF3 Capsize, Blobster
15may23, Mast Tabernacles, Laguna
1jun23, Underwater Boards, QT Skiff
15jun23, Capsize Lessons, Mixer
1jul23, Rend Lake 2023, Vireo14
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
JB Builds AF4
JB Builds Sportdory
Puddle Duck Website
Brian builds Roar2
Barry Builds Toto
Table of Contents