a week ago -- Chinese Dragon Boat, interesting vessel
The Chinese Dragon Boat
Appeal was made for a boatbuilder to look at an all teak dragon boat. I was interested, agreed to have a look and drove from Marblehead to Watertown just off the Charles River. There in the shrubbery surrounded by poison ivy and bayberry lay the vessel. A small work crew worked to clean the boat of five years accumulated leaves and compost. The last scoops of detritus were lifted out as I began to look at the structure.
The dragon boat is 38.5’ long with a beam a little over 3’. It is a paddle boat to be manned by pairs of paddlers with helmsman on the steering oar astern and a drummer on a chair at the bow. It is a ceremonial racing boat. Traditionally these boats are up to 100’ long, but for international racing the standard is 38.5’. The boats are usually brightly painted, often with scalelike features, and carry removeable dragon figureheads and tails.
This boat came from Hong Kong sometime before England gave up control of that territory. It came to New York one of twelve and was used for years in New York, as well as being let to other cities for their own dragon boat races. This boat was eventually given to a Boston group operating out of the Boston Children’s Museum. It was raced for some years, but as fiberglass boats were introduced and the old wooden boat had some structural problems, it was left in storage. From the storage building, it was put in the parking lot and then into the shrubbery. Now people who had paddled her before have sparked interest in getting her back in working condition. Peter Kai Jung Lew from the Museum and the Dragon Boat Festival was there with the work crew to inspect the boat, to judge it’s potentiol for restoration.
Walking up to the boat I saw a 38 foot long five plank teak dory open at the ends, but I quickly began to see the details and continued to pick out new details for the next two hours. There are more details hidden in the structure.
The Keel, Garboards and Topside Planks
The hull
The keel is 1 3/4 or 2 inch teak from 4 inches wide at the ends to a foot wide through much of the boat with a inch and a quarter rabbet cut 7/8 inch deep along it’s edges. The rabbet is cut slightly deeper on the inside so that the garboard strakes that form the rest of the bottom of the boat pitch slightly down, giving the dragon boat bottom a slight hollow along it’s length. The keel is bent to give rocker to the bottom and the garboards, sweeping from nothing at the ends to 5 inches amidship, are copper rivetted to the keel. The garboards outer edges are beveled on the miter to provide the faying surface for the lower topside planks. The lower edges of the lower topside planks are likewise beveled on the miter defining the lower chine angle. The upper edges of the lower topside planks and the lower edges of the upper topside planks are beveled on the miter in the same way to the same end. The chines are joined through the miter with nails (not having removed any I could not determine if the nails are wrought iron or copper). The nails are driven diagonally through the upper plank into the lower plank, this applies to both the upper and the lower chines. The upper topside plank stands plumb, with the lower topside plank approximately on a 45 degree angle.
All these planks and the keel are joined two part pieces. The Keel is joined using a long shouldered and keyed V type scarf joint that looks like a crocodile mouth three quarters of the way aft. The joint is tight, and secured with nails driven diagonally through the middle of the joint at four to six inch intervals. The nails are likely iron but the heads are set in pockets that are seen as grooves square to the joint and 1 1/2 to 2 inches off the seam. The garboards pieces are joined with scarf joints, riveted. The lower topside planks have butt blocks, the butt block a couple of feet long and copper riveted. The upper topside planks fit together with tongue and groove joints, but are secured with a plank doubler that functions as a full length butt block, holding the joint tight.
The ends of the vessel are open. The keel rabbet and garboards are not evident in the ends as the bottom narrows at both ends with the lower topside plank joined directly to the keel. The lower topside planks and the keel are less than 4 inches wide at the ends. The upper topside planks, almost full width within two feet of the ends, are trimmed down on a diagonal almost to the joint at the ends, with notches in the upper edge that hold the dragon head and tail attached for races.
Interior Structure
Chine Log, Seats, Bulkheads, Keelson, and Doubler
There is a chine log inside the joint between the topside planks. I believe it is nailed from the outside. The chine logs are shaped to the chine, but generally 2 x 4. The chine logs are each made up of two pieces joined with a short scarf joint. The seats are 4 1/2 inch wide by one inch and are nailed to the upper edge of the chine logs, two nails each end. Five of the seats rest on bulkheads fit to the shape of the hull with limber holes in the corners to allow water to flow to the low point of the boat. The bulkheads have diagonal 1 x 1 1/2 inch braces clinch nailed to their outside face that are morticed through the middle of the lower topside planks. What I call a keelson is a 2 1/2 x 3 inch timber the length of the boat, lashed to the tops of the seats down the middle. The keelson is made up of two pieces through a long 4 foot scarf in the middle. In the middle of this scarf a 1 x 10 inch mortice is cut. In the middle of the mortice is a 1 x 2 inch brace morticed through the keel below, standing 8 inches above the keelson and wedged in the mortice with four wedges (two fore and two aft). The wedges have slightly rounded tops.
The upper topside planks are doubled above the seats. Landing on the seats the doublers are screwed to the topside planks with upper and lower fastenings roughly every eight inches. The doublers are finished flush with the top of the plank. They are also two pieces joined, but the joints differ. The starboard doubler is joined toward the bow with a shouldered keyed scarf joint through the siding of the board, riveted. The port doubler is joined with a shouldered keyed scarf joint through the molding of the board, the board being molded 10 inches at this point, the joint is 3’ long. The doublers end with ogees on the underside extending just past the outer topside planks where they angle down. At the bow, there is a thwart morticed into the top of the doubler, morticed to carry a seat for the drummer. At the stern there is a heavy thwart extending a foot beyond the port rail with tholl pins toward the outboard end for the steering oar. At the outboard edge of these thwarts there is a 1 x 1 1/2 inch timber morticed through the keelson and through the keel.
These are the structural elements of the boat. All the wood parts are teak.
Other elements of the dragon boat and observations
Three of the seats are morticed through above morticed blocks nailed to the keel for carrying flag staffs. The major flag is carried on a square staff through a midship seat. the other two staffs are round, judging by the shape of the mortices.
There are 1 x 1 inch stretcher cleats to brace the paddlers feet ahead of each seat.
There are significant checks in the starboard upper topside plank running almost it’s entire length. This it the only major failure of the wooden structure. There is a relatively short but significant check at the bow through the lower topside plank port side. These need attention for the boat to be again functional.
The starboard doubler fasteners have failed and are only holding at the ends. It needs to be refastened. The rails are open at the top with the seam between the plank and doubler exposed. The paddlers brace themselves against the rails. The doublers are significant structural elements of the rail and need to be secure. I recommend that the doublers be unfastened to allow cleaning in the joint and then refastened with new secure fasteners. -- Thad Danielson
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