I'm building a traditional 18 foot Grand Banks dory. The dory will be discussed in a future Instructable but thought it might be interesting to focus on how I constructed the ribs which are the heart and soul of the dory, or more properly, the skeleton of the dory which supports the entire rest of the boat.
I have used a combination of traditional and modern techniques and a lot of help from friends and family that I refer to as the "planking crew."
The dory is being built with plans from http://www.doryplan.com/. Henceforth, I will refer to as the Plans. Unless permission is granted, I will not discuss dimensions but will show my woodworking techniques. You can purchase the Plans for $49.99 and obtain the dimensions. The Plans are conversationally written, as I expect you would receive if you visited their boat shop and shared a cup of tea.
In summary, the rib construction involved learning the traditional building method from The Dory Book, harvesting white oak logs with a major branch sticking out at nearly the correct angle, milling the logs into 1 inch thick boards, drying boards in solar kiln, planing boards from 1 inch down to 3/4 inch (20 mm) thick, using a plywood form to mark and rough cut the rib shape from the oak board, use the same plywood form and a router to create the final rib shape, and join 2 halves with a finger joint for installation. Each of these tasks will be discussed in detail in the following Steps.
A word on nautical terminology. There is a lot of it and I'm just learning it. Jack left port (i.e., left = port) is my starting point. And there are multiple words for the same thing. Ribs = frame = brace = knees and sometimes are combined like knee brace. I'll use "ribs" throughout.
The primary purpose of the dory is to carry picnic supplies and picnic princesses (i.e., persons not rowing) to islands off the coast of Maine. There are a lot of picnic princesses in our family, hence, why I am building an 18 foot boat.
Step 1: Traditional Building Method From the Dory Book by John Gardner
The Mystic Seaport kindly gave permission to use pages from the following:
The Dory Book, by John Gardner - This book is the most comprehensive book on dories ever published. More than a decade in the making, it is at once a history of the dory, a practical handbook on how to build a dory, and a compendium of dory designs with full construction details. 8 ½" x 11", 275 pages, 153 illustrations, 23 plan sets, index, paperback binding. Purchase from Mystic Seaport at http://www.mysticseaport.org.
I highly recommend The Dory Book to anyone interested in dorys. The Mystic Seaport is also a very cool, working, maritime museum. The museum is currently renovating a former whaling ship. You can almost smell the tang of the salty air.
A traditional method for constructing a rib or any other boat part is to find wood in the shape that is needed instead of either bending the wood or constructing from multiple pieces. The Plans called for three pieces. Using my method, it only requires two pieces. This reduced any weaknesses at the wood joints due to my substandard carpentry skills. Substandard to sh***y is how a Scottish friend would express it. In addition, the three pieces of wood creates a pocket to trap water with a potential for rotting. Water is only good on the outside of a boat. Not so good on the inside.
I literally took pages from The Dory Book, made a crude drawing to explain what heck I was doing and to look for suppliers. Refer to the 3 pages shown below. The idea is to obtain a white oak log with a branch sticking out at the correct angle to create a "hockey stick" and then join a pair of the blades of the hockey sticks together to create a complete rib. Refer to page 68.
In a Reny's store in Topsham, Maine, an old dory is part of the store displays and has ribs constructed as described in The Dory Book. I had to move the pillows to obtain the photo of ribs.
White oak was chosen because it was locally available, incredibly strong, and well suited for boat building because the cells of white oak are filled with tyloses, which restricts the movement of water. In contrast, red oak lacks the tyloses and water could move through red oak like a straw. The Plans called for mostly pine. Since white oak is roughly twice as strong as pine, I generally used boards with half the thickness of the pine boards, called for in the Plans, to have the same strength but reduce the weight of the boat.