Timothy Graul Marine Services 
located at 211 North Third Ave.
Mailing address: P.O. Box 290, Sturgeon Bay, WI 54235.
Phone: 920/743-5092 FAX: 920/743-7936
Email: information@TimGraul.com



To visit the schooner site for information and schedules, visit

By Mark D. Pudlo, Member, Chief Naval Architect, Timothy Graul Marine Services, Sturgeon Bay, WI

Presented at the fall meeting of the Great Lakes and Rivers Section,
October 27, 2000

The design of the three-masted schooner DENIS SULLIVAN is presented, with discussion of the vessel's origin and purpose, design background, regulatory issues, arrangement, performance and construction. Specific features of the design considered noteworthy are discussed, including structural criteria, tonnage, machinery, stability, watertight doors and launching.

The DENIS SULLIVAN is a reproduction of a typical Great Lakes schooner recently completed in Milwaukee, Wisconsin. Wooden schooners were instrumental in the development of the regions and markets surrounding the Great Lakes, as they providedSchooner Dennis Sullivan the most suitable means for transportation of bulk commodities prior to the age of steam. This three-masted schooner will provide a glimpse at what would have been a common sight in any Lakeside port during the nineteenth century, as various sources indicate that the total number of schooners having served the Great Lakes prior to 1900 exceeded three thousand. The DENIS SULLIVAN is operated by the Wisconsin Lake Schooner Education Association (WLSEA), a not-for-profit organization which has spent the last five years constructing the schooner at its "shipyard" on downtown Milwaukee's lakefront.

Design Background
Timothy Graul Marine Services was selected in 1993 to provide the design and working drawings for the schooner. We began the project by establishing the vessel's missions, and found that these missions went through some evolution over the several years that the project progressed and as the Association went through organizational changes. Primarily, the missions are as follows. First, she will be a tangible link to Wisconsin's maritime history. Second, she will be used as a floating classroom to educate people of all ages in the history and ecology of the Great Lakes. Third, she will be used as a vehicle to teach seamanship, sailing and responsibility to youths and adults. Finally, she will be a floating symbol and "good will ambassador" for the State of Wisconsin.

Accomplishing these missions required that a number of regulations be complied with. The ability to take on paying passengers was considered from the outset to be a necessity to ensure the financial viability of operating and maintaining the vessel. This means that the vessel must be inspected by the US Coast Guard, and in fact the vessel carries dual certification as a Small Passenger Vessel and a Sailing School Vessel (subchapters T and R). In addition, an International Load Line assignment is required to operate between separate ports. The Association also chose to class the vessel through the American Bureau of Shipping.

With the objective of creating an accurate replica, we researched old schooner plans, photos and books. The Association favored the general appearance of the fast and attractive schooners designed and built in the 1800's by William Bates in Manitowoc, Wisconsin; among them the CLIPPER CITY and the CHALLENGE. We also relied heavily on information made available to us about the schooners LUCIA SIMPSON, ROUSE SIMMONS, and MARY ELLEN COOK. Of great value were photos taken during a 1986 survey of the hulk of the ALVIN CLARK. Known as the "Mystery Ship", this vessel was raised from the bottom of Green Bay virtually intact and set up on shore as a museum in Menominee, Michigan. Regrettably, though, she quickly deteriorated due to lack of proper preservation.

Because most Lakes schooners were built to haul cargo (limestone, coal, lumber, cordwood, ore, etc.) at minimum cost and maximum efficiency, they tended to have "full" forms: rather blunt bows, flat bottoms and slab sides. Shallow harbors, rivers and canals common in the Lakes also caused them to have low deadrise bottoms for minimal draft, while relying on large centerboards to help them sail to windward. Both two and three-masted arrangements were common on these relatively small vessels, and many employed a large triangular shaped square-rigged topsail on the foremast called a raffee.

The DENIS SULLIVAN closely resembles a Great Lakes cargo schooner above the waterline. Her rigging is authentic, as is her deck arrangement. Below the waterline and below decks, however, concessions have been made to satisfy the intended mission as well as Coast Guard regulations.

The requirement for below deck accommodations with full headroom dictated that the hull depth be increased from what would have been conventional for a cargo vessel. As a result, a lofty 6 foot 4 inches of clearance below the deck beams has been achieved inside the DENIS SULLIVAN.

Modern stability regulations for a sailing vessel carrying passengers are far more stringent than anything the old Lakes schooners could likely have met (as the number of them on the bottom may testify to). These stability regulations are discussed later in this paper. To satisfy them, the hull is made finer and deeper than would be traditional, with substantial ballast in the form of 89,000 pounds of lead blocks bolted to the bottom of the keel. A further concession to modern regulations are the watertight bulkheads below deck, sufficient to comply with passenger vessel subdivision requirements.

The centerboard is eliminated altogether, as it is no longer required given the added depth of the hull and keel. A large centerboard trunk in the middle of the vessel would also have seriously compromised the accommodations spaces below deck. In addition, there are two propellers at the stern, to assure that no matter the wind, the DENIS SULIVAN will always be able to reach her destination, and not require tug assistance to enter or leave port.

On deck will be found all the aspects of a traditional working sailing vessel: anchors at the bow, a hand operated windlass, pin rails and posts for making fast the various lines, companionways to spaces below, a large aft deckhouse, and a helm at the stern. Not so traditional are boxes for lifejackets, a rigid bottom inflatable tender/rescue boat and a hydrographic winch for research work. In the deckhouse is a classroom/lab area, chart table, navigation station, head and Captain's quarters.

Below deck, the ship is divided into three main living spaces abaft the forepeak. The forward-most is a small crew berthing area, while the middle compartment has berths and two heads. The after living compartment contains a galley, mess area, and more berths. There are a total of 28 berths on the vessel (they are "schooner style", which is to say cozy), three heads and two showers. Aft of the galley space is the engine room, with a peak space at the stern.

The DENIS SULLIVAN took her maiden sail the first week of November, 2000. It having been decided that the vessel should spend the winter in active service, which was not possible in Wisconsin, a delivery trip to Florida in late November proved to be the real sea trials. At the time of writing, the vessel is preparing for its return, and has more than 3600 miles logged under the keel.

The schooner has performed very well, the owners claim, and displays particularly good light air performance. It is reported to be exceptionally dry on deck in all conditions owing to the amount of flare in the bow sections, although this flare is said to slow the boat down a bit when pounding into a head sea. Top recorded speed under sail during the delivery trip was between 11 and 11.5 knots on a beam reach in a 40 knot gale, with lower sails only, under single reef.

Auxiliary power is ample, maintaining an 8.5 knot cruising speed at 70 percent of rated engine rpm. Motor sailing is found to be very quiet and fuel-efficient with only one of the twin engines running at about half rated rpm.

Various construction schemes were considered at the outset, and the initial concept was to build the vessel "minesweeper fashion", using laminated frames and multiple glued layers of planking. The primary motivation behind this approach was the close involvement of Peterson Builders, Inc., a shipyard in Sturgeon Bay, Wisconsin, then active in the Navy wooden minesweeper construction program. The difficulty of obtaining large timber was also a consideration. Peterson Builders were to fabricate all the primary structure for the schooner in their laminating shop and freight it down to the construction site in Milwaukee. After delivering the first and largest piece - the keel, the Peterson yard unfortunately closed, forcing the Association to set up a laminating shop on-site and fabricate all of the laminated structure themselves. Oak laminations are glued with resorcinol-resin glue under controlled environmental conditions, requiring significant clamping pressure and heat for curing.

After hiring a master builder, it was decided that traditional planking with caulked seams would be preferable to multiple layers or cold-molding for authenticity, ease of repair, longevity in fresh water, and familiarity of construction methods.

Hull construction consists of laminated one-piece white oak frames set 22 inches apart on a laminated oak keel that is 24 inches wide by 15 inches deep. The frames are about 7 inches by 18 inches at the heel, and 7 inches square at the head. A 20 by 15 inch keelson rides on top of the frames on centerline. The hull planking is 2-3/4 inch thick white oak. Laminated sheer clamps, shelves and ceiling planks inside add longitudinal strength to the hull, while steel diagonal strapping helps resist hogging loads as well as the loads imposed by the masts and rigging. Deck planks are 2-3/4 inch thick Douglas fir. Main deck beams are laminated Douglas fir, 7 inches square in section, with several sawn knees to tie them into the frames. All hull and deck seams are traditionally caulked.

Structural Criteria
As an inspected vessel with a Load Line, the DENIS SULLIVAN falls under the review of both the Coast Guard and ABS for structure. Our approach was to establish scantlings consistent with traditional construction, and then verify their adequacy against the rules. There is, however, no current rulebook available that can be considered applicable for scantling review for a vessel of this type. While ABS considers the Rules for Building and Classing Offshore Racing Yachts to be the "official” standard applied to this vessel for structural review, it was found to be inapplicable or inappropriate in many areas, and we conducted an analysis of the various members by employing a combination of requirements from the following standards:

  • Lloyd's Register Rules and Regulations for the Classification of Yachts and Small Craft, 1978
  • ABS Rules for Building and Classing Offshore Racing Yachts, 1986
  • Nevins Proposed Scantling Rules for Wooden Yachts, ca 1935
  • ABS Rules for Building and Classing Wood Vessels, 1942

For the schooner to qualify as a small passenger vessel under Subchapter T of the Coast Guard regulations, it is necessary that it admeasure less than 100 gross tons. The initial design approach was to employ a deep framing scheme to achieve the desired tonnage using the U.S. standard measuring system, as is common practice for obtaining "artificial" tonnage for regulatory purposes on U.S. vessels. Further investigation, however, showed us that the dimensions of this vessel were just right (by sheer coincidence) to measure in at 99 gross tons using the International Tonnage Convention (ITC) system, thus eliminating the need for deep framing or other tonnage "gimmicks".

Two interesting tonnage interpretations were discovered in the process of working out the tonnage: First, for a wooden vessel, ITC tonnage volume must be measured to the outside of the hull planking, and to the underside of the deck. Further, the Coast Guard ruled that the lower terminus of volume measurement would be the keel rabbet line, so that we did not have to include the volume of the solid keel or ballast below that line. For structures above the tonnage deck, volume is measured to the inside of the house planking. Secondly, had the US standard tonnage method been employed, it was ruled by the Coast Guard that we could have used tonnage floors of steel construction attached to the wood frames, provided that equivalent strength was demonstrated.

Machinery Installation
A twin-screw propulsion arrangement was requested by the Association for reasons of redundancy and enhanced maneuverability. Two Cummins 6BT5.9-M engines were selected, each rated 180 BHP at 2500 rpm, coupled to Twin Disc MG 506-1 gears with a 2.96:1 reduction ratio. Propellers are 34 inch diameter MaxProp self-feathering type, which offer reduced drag when under sail, and a shaft brake is fitted to prevent their rotation when not in use.

The diesel engines are mounted on steel foundations bolted to the wood frames. "Aquadrive" constant-velocity joint shafts and thrust bearings are employed between the engines and the propeller shafts, which enables the engines to be very soft mounted for reduction of noise and vibration, and also eliminates any concerns about engine alignment. 

The engines have wet exhaust, which exits through the side of the hull so as to be unobtrusive. Design of this system proved to be a challenge because the engines are installed below the waterline, yet must be capable of running (and exhausting) with the boat heeled over under a press of sail, without fear of water backflooding the system. The solution was to employ Maxim model TR3 silencers, which are mounted in trunks on each side of the deckhouse above the engine room. These silencers are unique in that exhaust enters up through the bottom (dry), while cooling water is introduced down through the top. The wet exhaust then exits through the side of the muffler and out the side of the vessel, thus providing an elegant and compact way of achieving necessary vertical rise and silencing in the tight space available.

A 20 KW diesel generator is installed. Its exhaust is small enough to be led aft and exit the hull below the transom on centerline, thus enabling a conventional waterlift type muffler to be used.

The stability standards for a passenger sailing vessel present a somewhat different challenge than what is typically encountered in the design of modern commercial craft. In addition to the weather criterion of 46 CFR 170.170, inspected passenger vessels over 65 feet in length which are monohull sailing vessels must comply with the criteria of 46 CFR 171.055. The range of positive stability must be greater than 90 degrees for operation on exposed waters, and greater than 70 degrees for operation on partially protected or protected waters. Additionally, the vessel's righting arm curve is compared to different heeling arm curves, with the purpose of assessing stability in three conditions: heel to deck edge, heel to downflooding, and knockdown. Upright heeling arms (HZA, HZB and HZC) are determined for these three cases based on relationships to the righting arm curve. Heeling moment is a function of the projected lateral area (A) and vertical lever (H) of the vessel's silhouette above the waterline, computed with all sail set and trimmed flat. A relationship based on comparing the moment generated by the upright heeling arm to (A x H) results in a "stability worth numeral". The respective numerals must be greater than or equal to the values specified, which are larger for exposed waters service than for protected or partially protected waters.

Sailing school vessels must also comply with this criteria (46 CFR 171.055), with relaxation of the "worth numerals" as allowed by 46 CFR 173.063.

Frequently, the exposed waters criteria will not allow a full set of topsails to be carried. Calculations for the DENIS SULLIVAN demonstrated that on exposed waters she may safely carry either the raffee topsail without main and mizzen fore-and-aft topsails, or the main and mizzen topsails without the raffee. On partially protected waters, she may carry the full complement of sails. It should be noted that outside of 20 nautical miles from a harbor of refuge, the Great Lakes are considered to be exposed waters between October 1 of one year and April 15 of the next year, and partially protected otherwise.

Watertight Doors
Watertight doors in main watertight bulkheads below the freeboard deck have been generally prohibited by subchapter T on small passenger vessels for many years now, although they are allowed on sailing school vessels less than 125 feet long. Most traditional craft that are not subject to the new T-boat rules have doors in the bulkheads below-deck for the obvious reason of accessibility between below deck spaces. A request was made to the Coast Guard for special approval of watertight doors below deck on this vessel, considering its unique characteristics as a traditional sailing vessel. The primary argument presented was that safety would be enhanced by eliminating the necessity of open deck transits from one space to another, especially in hours of darkness and inclement weather. This initiated a Coast Guard study that examined the arrangements and safety record of the fleet of similar existing vessels.

A ruling was made based on this study to allow watertight doors to be installed below deck, subject to certain provisions, most significantly: (a) the vessel retains dual certification as an SSV and passenger vessel; (b) suitable alarms are installed to indicate the open position; (c) the doors are not considered as a means of escape, and; (d) the doors must be strong-backed and padlocked when carrying passengers beyond a coastwise route.

In the end, the Association decided against installing doors below deck, other than for machinery room access. There are, however, other traditional vessels under construction which may wish to take advantage of this ruling.

Built on an asphalt surface within yards of a deepwater seawall, the original launching plan was to simply pick the vessel up with two cranes and set it into the water. The surprise came late in construction when the port engineers determined that the ground and pilings could not safely support the weight of two cranes while lifting the schooner. Much head-scratching went on to come up with the final solution. This involved building a large steel cradle under the craft, which was set on dollies to move the vessel to a position perpendicular to the seawall. It was then rolled onto a barge, and thus transported to Milwaukee's heavy lift dock where it was finally lifted and placed in the water.

For all who have played a part in building the DENIS SULIVAN, or have watched the long construction process with interest, it is exciting to see the finished vessel finally under sail, and see history reborn. Many people have played a role in this worthy project, which has drawn volunteers and supporters from throughout the Midwest and beyond. All funding and much of the materials, equipment and machinery has come from private and corporate donations. It is a community project, and the crew at Timothy Graul Marine Services are proud to have been a part of it. We hope that the DENIS SULLIVAN will be a distinctive addition to Milwaukee's waterfront for many years to come, while increasing public knowledge of the role that schooners and schoonermen have played in the history of Wisconsin.


   Chatterton, H. A. Jr. and Maxham, J. C., "Sailing Vessel Stability – With Particular Reference to the Pride of Baltimore Casualty," MARINE TECHNOLOGY, Vol. 26, No. 2, April, 1989, pp. 87-104
   Brooks, R. B. and Beebe-Center, J. G., "On the Stability of Sailing Vessels," SNAME, Chesapeake Section, March 2, 1966
Guide for Building and Classing Offshore Racing Yachts, American Bureau of Shipping, 1986
   Hirthe, W. M. and M. K., "Schooner Days in Door County," Voyageur Press, Minneapolis, 1986
   Inches, H. C., "The Great Lakes Wooden Shipbuilding Era", Great Lakes Historical Society, 1962
   Mansfield, J. B., ed. and comp., "History of the Great Lakes," two volumes, J. H. Beers, Chicago, 1899
  Marean, P. E. III and Long, R. W., "Survey of Sailing Vessel Stability Leading to Modified Regulations," SNAME, New England Section, Oct. 16, 1986
Nevins, "Proposed Scantling Rules for Wooden Yachts," source unknown, ca 1935
   Rules for Building and Classing Wood Vessels, American Bureau of Shipping, 1942
   Rules and Regulations for the Classification of Yachts and Small Craft, Part 2, Hull Construction, Chapter 4, Wood and Composite, Lloyd's Register of Shipping, 1978
   Shipley, R., "Schooners - Great Lakes Album Series," Vanwell Publishing, Ltd., St.Catharines, Ont., 1991
   U.S. Code of Federal Regulations, Title 46, Subchapter R, Parts 166–169, Nautical Schools
   U.S. Code of Federal Regulations, Title 46, Subchapter S, Parts 170–174,       Subdivision and Stability
   U.S. Code of Federal Regulations, Title 46, Subchapter T, Parts 175–187, Small Passenger Vessels (under 100 gross tons)



Timothy Graul Marine Services
211 North Third Ave.
P.O. Box 290, Sturgeon Bay, WI 54235.
Phone: 920/743-5092 FAX: 920/743-7936

Site designed and hosted by: Poverty Island "the web design company"