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Devlin Designing Boat Builders 
Celebrating Our 35th Year Building Fine Boats     
Last updated on: May 30 2014
"Stitch & Glue" Construction
Introducing the Devlin "Stitch and Glue" Method

Devlin Designing Boat Builders are master craftsmen when it comes to wooden boat construction. Our "Stitch and Glue" method is a vastly superior approach when compared to traditional boat assembly methods and delivers stronger, better boats. The Devlin Method uses epoxy to bond and seal all parts together thereby achieving a stronger, one-piece boat design. The initial construction is quicker, easier, and needs fewer parts. This approach does not require expensive building molds. More importantly, it results in a boat that is much easier to maintain over the long term.

"Stitch and Glue" construction is a technique using very high grade marine plywood, simple wire sutures (to clamp together the panels of the boat until they are fused together permanently), fiberglass tapes, fiberglass or Dynel Polyester cloths for sheathing, epoxy fillers, and epoxy resin. For a simple Vee-Bottomed boat, the basic steps for the builder are to cut out the two bottom panels, the two side panels and the transom. These parts are then stitched together with the wire sutures along the panel edges or seams. The wire sutures clamp and hold the panels together until the epoxy/fiberglass cloth fusing mixture is cured, then the wires are removed.  For this fusing joint, the epoxy resin is thickened with the fillers or hardwood flour (finely ground hardwood sawdust ) and then applied to the seam in a thick, continuous bead over which layers of fiberglass cloth tape are applied. Each tape layer is completely saturated with Epoxy resin before applying the next layer (wet on wet). Once all the interior seams have cured up (overnight), the hull is turned over, the wire stitches (sutures or clamps) are removed and the seams and edges are smoothed over and faired in anticipation of sheathing the entire exterior of the hull with fiberglass or Dynel using the epoxy resin to completely saturate the cloth. The key to the method is that all of the structural surfaces must be saturated with the resin. Using marine quality materials will always ensure a quality product.

When you purchase a set of plans, we include a step-by-step building booklet, a materials list, a source list, and even a list of the tools necessary for the basic construction. One nice thing about "Stitch and Glue" construction is that fewer tools are required compared to other methods of construction.

"Stitch and Glue" construction allows the builder to once again utilize the strength and beauty of wood while eliminating the negative maintenance problems so prevalent in the past with wooden boats.

The Advantages of "Stitch and Glue" Boat Building

The differences between conventional plywood-on-frame and "Stitch and Glue" construction are significant. To better understand the differences between the two, contrast the structural dissimilarities of an early biplane and a modern jet airliner. The biplane was made up of frames and spars over which was stretched a thin skin. The jet airliners structure, on the other hand, is much simpler, with a stressed aluminum skin rigidly attached to bulkheads and spars to create a single monocoque unit. A boat built by attaching plywood planking to lumber frames is most similar to the biplane; a "Stitch and Glue" more closely resembles the jet airliner, a homogeneous structure in which the skin bears the primary stresses.

The basic argument for "Stitch and Glue" construction is that it uses fewer parts and that epoxy is used to bond and seal the parts to achieve a stronger, monocoque (one-piece) boat. The initial construction is quicker and easier, uses fewer parts, requires no building molds, and all parts of the boat contribute to the structure. And in the long term, the boat is much easier to maintain, mostly because the structure is so very strong and all the surfaces are carefully and completely sealed with the same epoxy resin that was used to bond all the parts together thus keeping moisture and water from migrating into the dry wood.   If you keep the wood dry then paints and finishes aren't prone to cracking and peeling off and the wood in the structure is mummified from the possibility of rot, which requires considerable moisture in order to flourish.

Looking back over my own development in boatbuilding, and considering the advantages and disadvantages of the many forms of boat construction I've used, I find my memory foggy as to why I chose one form over another. In the beginning, I was simply working out the differences and identifying the problems of each form of construction. I knew that working with natural wood products was appealing, and I knew I wanted to use wood products in an ecologically sound manner. A boat built of wood has a spirit that is easy to see and feel, but much harder to define. "Stitch and Glue" simply produces the strongest structure, is easiest to approach for either the experienced builder or the "first time builder" and results in a product that the builder can be proud of for a very, very long time!

Almost all boatbuilding methods require expensive tooling. Production fiberglass boats have their elaborate plugs and molds. Traditional plank-on-frame or cold-molded wooden boats require complicated building molds. This expensive tooling can tend to stop much of the evolution of an individual boat design. "Stitch and Glue" construction does not bear this initial burden. With no building molds or tooling to consider, a "Stitch and Glue" design has a chance to constantly evolve and improve and that's important! I believe that any design can use refinement, and as my own design work has evolved, I have found ways to increase the ability of the "Stitch and Glue" boat to even more appropriately suit its purpose and meet its owners performance requirements.

Lofting

In almost any boatbuilding method, the builder must carefully draw out, in full size, what the plans of the boat show in small scale.  Much time spent on your knees laboring over huge painted sheets of plywood trying to accurately draw long lines is typically not my idea of fun.  I clearly remember my confusion at the prospect of lofting my first boat. It seemed such a waste to spend so much time on a pursuit that didn't seem to have much to do with boat building and I quickly realized that even the most careful approach to the task would still result in a fairly inaccurate result.

In "Stitch and Glue" construction, several building basics or norms of traditional boatbuilding are altered. First, there are no building molds required and no complicated lofting of molds or support structures are necessary. Second, the lofting required is not to draw a full size picture of the lines of the boat, but to draw a full-size picture of the parts. For a simple V-bottomed boat, the parts required for a basic hull are two side panels, two bottom panels, and a transom, drawn directly onto the plywood that will be cut out and used for those parts.

In the designs that I offer for "Stitch and Glue" construction, I have made the conversion from three-dimension to single-dimension for you. I have essentially "peeled the boat", laid it out in a flat plane, drawn a picture of it, and scaled that drawing so it can be easily duplicated. So when you look at a drawing of the panel projections for the boat, you are looking at a scaled drawing of the skins or sections of that boat.

A panel-projection drawing is scaled out so that it fits on flat sheets of plywood, the very same ones that we will use to build the boat. If we lay out that sheet of plywood horizontally in front of us, the left edge or small edge is the station baseline. All stations are measured out from that edge parallel to each other at a fixed interval. In our example, the station space is 12", so every 12" for the length of the panel, a straight line is drawn perpendicular to the baseline, or long edge. When those lines are drawn and labeled, the actual offsets can be drawn in. The bottom long edge of the panel is our baseline, and a tape measure can be hooked over that edge and pulled out alongside the station line, measured and marked.

The rule in lofting is feet, inches, eighths. If a dimension says 1-10-4, then that translates to one foot, ten inches, and four/eighths, or one/half inch. A dimension that say 2-4-0 is two feet, four inches, and zero eighths and this rule is the same for all dimensions in the panel.

Once all the points are marked onto the plywood panel, you can connect the dots with a long, fair batten (a long staff of dimensional wood that can be bent around the marks you have made on the panels) and cut the parts out. This essentially is all the lofting needed for you to start construction and you are free to concentrate your energy on building the boat.

Why Wood?

At Devlin Designing Boat Builders we know wood.  We have been using wood in the marine environment for more than 30 years and can unequivocally say that wood is the best choice.  Read on.  In an era of modern materials such as fiberglass and aluminum, you might wonder how we could possibly make this claim.  When compared to other alternatives, wood has many significant advantages as a construction material for many types of marine craft.

  • Better resistance to stress - Wood is the most resistant to constant direct force... the kind like the structure of a boat gets due to the pressure of the water on the hull.  And the faster the boat goes, the heaver the force is. One well-known test was done on various materials to find out how well they hold up under constant pressure.  Each material was put under direct pressure for 1 million cycles for 30 hours at a time.

  •  
    • Straight Fiberglass kept only 22% of original strength
    • Aluminum kept 37% of original strength
    • Wood with epoxy kept 64% of original strength.
       
  • Better thermal, galvanic and acoustic characteristics - Wood has better thermal and acoustical characteristics than other materials so there are greatly reduced problems with condensation on the faces of the interior hull. Its galvanic characteristics are also ideal. Galvanic corrosion occurs when two dissimilar materials come in contact with each other and one causes the other to corrode. Wood does not have this problem.
     
  • Best aesthetics and visual experience - No one can doubt that in terms of look and feel, you can't beat the feeling of wood.  The aesthetic characteristics of wood and the visual experience it brings are far superior to the synthetic experience of other types of boats.  With its warm and natural beauty, the feeling you get when staying on board surrounded by natural materials contributes to your joy of ownership.
     
  • Comparable maintenance costs - Traditionally made wooden boats typically have a high cost of maintenance. This is not true of Devlin boats because all wooden parts of our boats that are exposed to the sun or sea are protected by our epoxy coating.  Technically speaking, when dry wood is protected in this manner, it maintains all its extraordinary characteristics, practically without aging for decades. Maintaining a Devlin boat is no more expensive or time consuming than that of a fiberglass boat.

When compared to other materials such as fiberglass, aluminum, or even steel, wood is actually stronger when you look at the relationship between its strength and its weight.  This means that a wooden boat when compared to synthetic boats of the same size and weight, the wooden boat will have the least weight.  It also means that when compared to other construction materials, that same wooden boat with have the greatest strength. Bottom Line:  Wood has the greatest strength per volume of weight and that makes it highly suitable for boat building where the material needs to be light but strong.

The Stitch and Glue Upside Down Building Sequence by Sam Devlin

The sequence for building first starts with a building jig or framework as in illustration (1a). Mark out the interval of the building bulkheads or molds on the jig's top surface. Depending on your design, they will either be bulkheads that will stay in the structure or molds that are temporary and don't stay in the finished boat, or even a combination of the two types. A centerline is also necessary to help keep everything lined up.

Now you can set your molds up on the building jig as per illustration (1b) and brace them to set vertically from the jig floor. All the waterlines should be at exactly the same measurement from the top surface of the jig and the centerlines of all the molds must be in alignment. The more careful you are during this setup stage, the easier your building project will be.

I have shown the wire frame of the hull now projected onto the jig so that you can see how the hull panels will line up with all the molds or bulkheads in illustration (2a). In illustration (2b) you can see the outline of the waterline now as it relates to the top surface of the building jig and to each of the molds or bulkheads.

Once everything is all lined up and set up properly, we are now ready to cut out the two bottom hull panels and stitch them together. In illustration (3a) you can see the two panels off the molds yet but just about ready to come together. You will stitch the two bottom panels together at the keel line or centerline of the hull face to face like the pages of a closed book. Then by opening up the panels (like opening up a book upside down) and laying them over the molds, we are ready to apply those first panels to the setup. There should be an orientation mark on the bottom panels that will show where you need to position the panels fore and aft on the molds.

Now that the bottom panels have been set into place, you are ready to stitch the lower side panels into position (see illustration 4a). Start at the bow and stitch or staple (see "New Stitch and Glue Technology") the panels along the length of the chine from the stem end to aft. You should have cut and beveled the double 45 degree angle on the inside edge of both of these panels at every edge of all of the panels except the sheer panel at the sheer edge. The double 45 degree bevel will allow the panels to lay alongside each other nicely and the molds will work wonders in keeping the panels all lined up and fair. At this point, don't fasten any of the panels to the molds but use the molds only as a framework for the panels. It's kind of like stitching together a hat of the hull panels and then putting the hat over the molds like putting a hat on your head (as in illustration (4b).

Now you can stitch or staple the two sheer panels to the stitched up parts you have already draped over the molds (as in illustration 5a and 5b). As in the lower side panels, start at the stem and work your way aft along the seam, stitching or stapling as often as it takes to keep everything lined up nicely (4-6" intervals are about right). Keeping both the sheer panels together in the bow symmetrically is very important and will give you a more fair hull.

With all the hull panels now in place and draped over the molds like a hat (as in illustration 5b), it is now time to attach the transom. The longitudinal (lengthwise) mold will assist in placing the transom at the proper angle to the hull panels (as in illustration 6a and 6b.) You can stitch the transom or fasten to the hull edges at the intersections to hold it in place and make sure to keep both sides of the hull panels in the same relationship to the transom. To explain that last statement a little better, if there were an overlap of the sheer panel on the starboard side of the boat by say a 1/4" at the transom and if the transom were in proper position and placement, then there should be the corresponding overlap on the port side of the boat. Symmetry from side to side is the rule here. Once all is done and in proper position, it is now time to tab the interior seams of the boat with thickened epoxy. This is like tack welding in metal work and will hold the panels together until the stitches or staples are removed and you can glass the exterior.

Our Book & Video

To better understand the "Stitch and Glue" boat building method, we have produced a Video/DVD "Wooden Boatbuilding with Sam Devlin" and published a book "Devlin's Boatbuilding" on the subject. These were created to help those with the desire to build their own boat. Click on the book or video for more information.

  

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Devlin Designing Boat Builders
3010 37th Ave. S.W.
Tumwater, WA. 98512
(360) 866-0164
Email Sam Devlin
www.devlinboat.com

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