Saint Barbara

SAILBOAT DESIGNS

SAINT BARBARA

Saint Barbara at Van Dam Woodcraft in Boyne City, Michigan. For more construction photos, see the end of this page.

PARTICULARS

Loa: 37’ 6”

Lwl: 34’ 6”

B: 13’ 6”

D: 10’ 0”

Displ: 11,056 lbs. at Dwl

Ballast: 4,421 lbs.

Sail Area: 720.0 sq.ft. (including mast)

Displ/(.01Lwl)³ 119.16

SA/Vol^2/3 22.90

Genesis of the design

Sam Kovalak of Rockford, MI, is the owner of Saint Barbara, his new Sponberg-designed 37.5’ wingmast sloop which is being built by Van Dam Wood Craft in Boyne City, MI. This design had a long, long gestation period—11 years. That was the time between Kovalak’s first phone call to me inquiring about a new boat, and the signing of a design contract. This is a record for me. In the interim, Kovalak did a lot of reading on boat design. He even bought a few boats simply to research boat performance and to figure out precisely what he wanted in a new boat. The concepts of wingmast rig, lifting keel, and rudder-in-a-drum had particular appeal, and actually, these were constants throughout a long process of introspection. The one other constant from the very beginning was that Steve Van Dam would build the boat.

Kovalak’s initial phone call to me focused on a 32’ trimaran. Three years later it was a 32’ cruising monohull. Then two years after that he bought a Dragonfly 1000, a 33’ trimaran which had nice performance, but its construction was a little light for his tastes. The following year we were talking about a 38’ yawl, which two months later was simplified to a 33’ sloop. By the end of the next year, we were back up to a 39’ sloop. About 18 months after that, Kovalak bought an Alerion 28 sloop to putz around Mackinac Island in Lake Huron. The next year, contemplation was onto a 35’ glorified daysailer, very lightweight and very fast, which a month later grew to 38’ again. We were still two years away from a design contract. In January 2002, we started settling into a design that was looking a lot like what actually transpired--LOA at 38’ 4” and a weight of 10,500 lbs. Six months later with contract time T-14 months and counting, the boat grew to 41’ LOA and 10,800 lbs. displacement. But that held until the following autumn when the contract was signed for a 41’ sloop.

I have never experienced so much design whiplash in my life.

But not all was settled. During the development of the 3-D hull shape, the first stage of the design process, the boat grew to 44’. After 7 different renditions of the hull shape, and with a little dose of reality about construction cost (which varies according to the cube of length overall), the boat finally settled in at 37’ 6” LOA and about 11,000 lbs. displacement. At 37.5’ LOA, the cost of the boat met a budget close to $250,000, but at 44’, the cost would have been over $400,000. The renderings that follow show the final hull, deck, keel and rudder geometry as created in ProSurf and rendered in Rhino.

During all this time, Kovalak and I traded faxes, letters and phone calls about rigs, keels, rudders, hulls, and performance. He obtained quotes from sailmakers and keel builders to figure out costs for construction. He learned a lot about boatbuilding and engineering from Meade and Jan Gougeon at The Gougeon Brothers Inc., makers of WEST System and Pro-Set epoxies, the most popular and versatile epoxy resins used in boat building.

Another constant in this whole process is that Kovalak is an engineer himself, from my alma mater, the University of Michigan. He owns a very large sign company with facilities big enough to do some of the inventing, milling, and manufacturing for various parts of the boat. Above all else, Kovalak wanted to participate hands-on in its contruction. This meant that my design work was greatly abbreviated, focusing on the geometries of the hull, keel, bulb, rudder, and wingmast. Kovalak, literally working over Steve Van Dam’s shoulder, figured out the hull and deck construction, thickness and lay-up (3/4” thick western red cedar strip planking with carbon fiber unidirectional fabric at 90° and ±45° inside and out), and where all the internal structure and gear would go. So structures-wise, I had little to do after the geometry was complete. Continuing through the process, I am consulted on various naval architectural aspects (hydrodynamics, aerodynamics, structures, etc.) as the need arises. This consultation is paid for in installments, and is, in fact, an unusual arrangement because it is very rare that the client is an accomplished engineer the way Kovalak is. But he is enjoying himself immensely.

Even after construction began, changes were made to the boat for simplicity and lower cost. For example, the coachroof shape and window layout were changed. I am not particularly enamoured with the result because I had developed some pretty sweet shapes that took a lot of time to get absolutely fair. You may judge for yourself by going to Van Dam’s website, www.vandamwoodcraft.com, click on “currently building”, and then click on “sloop” for complete construction photos. Some show the coachroof close-up. The rest of the structure and shape look great.

The other idea that did not pan out was a pair of stainless steel tubular rails that were to run the full length of the deck edge port and starboard. This was about 2” in diameter and fixed to the hull on short tube-and-plate pedestals mounted about every 18”. Their purpose was to provide very strong rails on which to mount just about anything—mooring lines, running rigging, harness tethers, etc. In the end, it proved to be so complicated and expensive to fabricate and install that it had to be dropped. Conventional hardware took its place. You can see the rails in both the sail plan above and in the deck plan below. These are deleted from the actual construction.

Keel and rudder design

There is nothing really too remarkable about the appendages, at least regarding their section shapes. Both employ a modified LS-(1) aerofoil section, which is one of my favorites because it has its maximum thickness at the 40% chord position instead of the more common 30% chord, it has a hollow trailing edge which leads to parallel flow coming off either side of the blade, and it is scalable to various thicknesses from a master pattern. Structurally and aero/hydrodynamically, it is very good. Both rudder and keel lift up, the rudder in a drum, and the keel in a keel box. The rudder is nearly neutrally buoyant and can be lifted by hand. The keel is much heavier, of course, and will be lifted by a hydraulic ram that lays horizontally on a platform next to the keel casing. The ram works through a reverse block-and-tackle system so that one length of retraction on the ram magnifies to many times that retraction on the keel. Kovalak engineered both systems, including the bearings needed for smooth operation of the rudder drum. The keel blade is solid wood with thick, wide sections of carbon fiber laminate inset into either side for primary strength and bending stiffness. This can be seen in the construction photos on Van Dam’s website.

We spent a lot of time getting the lead between the center of effort of the sailplan and the center of lateral plane area just right. In analyzing many other similar deep-keel designs, we concluded that the conventional rules of lead that one normally would follow in sailboat design simply fall apart. We found that the best guideline is to place the center of effort of the rig directly over the leading edge of the keel. We had the benefit of prior knowledge on my design Bagatelle which is very neutrally balanced, and her center of effort is a touch forward of the keel leading edge. So we think Saint Barbara is going to balance pretty well.

The other factor regarding the keel, of course, is the placement of the ballast bulb. Up until the final rendition of the hull shape, the bulb nose was coincident with the keel leading edge. But the weight estimate that Kovalak was calculating and monitoring showed that the boat would have a slight trim down by the stern. Another factor was that the weight hanging aft of the neutral axis of the keel blade would tend to twist the keel blade a little too much in the wrong direction. That is, the tip of the keel would stall (too much angle of attack) before the the root. Therefore, the last design decision was to shift the bulb 12” forward to a “T”-keel configuration to reduce vessel trim and keel twist. You’ll note that my bulb design follows the ‘Beavertail-Swallowtail” shape that I prefer, what I otherwise refer to as the “B.S. bulb” (pun intended). But It works.

Rig design

The newest technology in Saint Barbara, of course, is the rig. The mast represents my latest naval architecture on the concept of the design (wingmast over stub mast) with Kovalak’s preferences for the design of the boom and two unique spinnaker poles. The booms and spinnaker poles are both hydraulically vanged in a system designed by Kovalak. My input into the system was to concurr with and explain the aerodynamic advantages of the concept. These can be shown in the following diagrams, which Kovalak drew on an earlier rendition of the deck layout.

The first diagram below shows the basic layout of a spinnaker pole and the position of the hydraulic cylinder vang. Two of these poles are mounted on the fore deck.

In the next three diagrams, you can see the deployment of the poles and the headsail, a flat-cut symmetric spinnaker or a Code 0, tacked to the ends of each of the poles. As the wind backs from ahead to astern, the poles are rotated to maintain lift at all sailing angles. Note the rotation of the wingmast, too. Upwind, the rig behaves much like any other sloop, and so performance will be similar to most any other racing sailboat. But off the wind, both the mast and poles rotate, allowing the rig to generate tremendous lift. Lift is many times more powerful than drag, and so lift downwind will make the boat nearly twice as fast as any conventionally rigged competitor. See the Free-standing Rigs section of my website here for a more complete discussion of why this is.

If you look at the upwind diagram, you’ll see that Kovalak will be able to make Saint Barbara point much higher than any conventionally rigged sailboat. All he has to do is let the tack of the forward, windward spinnaker pole swing to the leeward side of the bow. As he does that, the angle of attack to the whole rig increases. The reduce that angle of attack better for upwind sailing, he’ll turn the hull further to windward. In fact, this works in direct proportion--for every degree of angle of attack that he shifts the spinnaker poles rig to leeward, the hull points a like number of degrees closer to the wind. This is exactly the whole reason behind sailing—to be able to point into the wind as closely as possible. You can do this with a free-standing rig. You cannot do it with a stayed rig. This is a big advantage for both racing and for cruising. But unfortunately for racing, moving the tack of the headsail is simply not allowed by the rating rules. Go figure. Again, see my discussion on Free-standing Rig Design for more detail.

Conclusion

Saint Barbara’s construction appears to be moving along pretty well, and from the photographs I can tell that the crew at Van Dam Wood Craft is doing a marvelous job. See more below.

Saint Barbara, by the way, is Sam Kovalak’s dedication to his wife, also named Barbara. The real Saint Barbara, according to my Dictionary of Saints, may or may not have been a real person. Reportedly a martyr from the seventh century, Saint Barbara “was a maiden of great beauty whose father, Dioscurus, shut her up in a tower to discourage the attentions of numerous suitors.” She became a Christian and was denounced by the authorities who later instructed her father to put her to death. No sooner had he done so than he “was struck by lightning and reduced to ashes.” Because of this fate, Saint Barbara provides protection from lightning. And as we all know, we don’t like lightning to strike carbon fiber masts. Reading this story, and knowing Mrs. Kovalak, Saint Barbara is a very fitting name for this boat.

Saint Barbara's hull during lay-up. Three layers of carbon fiber (90°, +/-45°) went over 3/4" western red cedar strip planking inside and out. This is the first layer on the outside.

The last of the carbon fiber goes onto the hull.

The hull is faired and is starting to be turned over.

This gives a good view of the inside with the bulkheads in place giving the hull rigidity during the turn. The entire inside of the hull is to be layed up with carbon fiber in a mirror-image of the exterior layup.

The hull and deck have been fully faired and painted, waiting for the boottop which has been marked, and all the deck hardware.

I visited Van Dam Woodcraft in July, 2006, to get my own photos and look in on construction. That's Steve Van Dam in the lower left corner.

From my vantage point in the shop, I could only get Saint Barbara in the picture diagonally, and if I rotate the picture in the photo editing software, the boat gets cropped. So just turn your head to get the best view.

I took this shot because I am on record stating how difficult it is with hull design software to get rid of any hollow in the bow sections. It is hard to fair hollow into the waterlines forward when drawing a set of hull lines by hand, but it is also hard to fair out the hollow in the waterlines forward when developing a hull on the computer. In Saint Barbara's case, I succeeded quite nicely in getting a perfect shape for the waterlines forward without any hollow.

Saint Barbara with myself, Steve Van Dam, and the owner, Sam Kovalak, feeling quite happy about the success so far for a design that's going very nicely. We are all waiting impatiently for the final assembly and sea trials next spring, 2007.