When talking stitch and glue boat building wood joining are often done with fiberglass and epoxy. This wood joining method is really excellent and flexible for many types of wood joining jobs like joining hull panels, frames etc.
However for some jobs we prefer other more traditional and old fashion types of wood joints. This is specially the case when working on yachts and small boats superstructure and interior.
The post is about the different wood connections and how to make them.
Let us start with methods for joining wood boards edge to edge. The most simple is to glue the boards together. This requires the edges to be newly machined and level. However when you have obtained this the joining method is really useful and when using the right glue also strong and durable.
Another common way to joint two boards is using tongue and groove. This method does not require as much care and in most lumber stores you can buy the boards ready made for assembly.
One variant of the tongue and groove joint often used in boat building is where the two edges both have grooves and they are then assembled using a loose tongue. This method is especially useful when the boards don’t have straight edges like dunnage made of plywood sheets.
Beside joining boards edge to edge you often want to join wood corner to corner like in picture frames etc. When talking this kind of wood joints there are also several different kinds of joints to use.
First and most simple is the miter. Even though this joint is widely used in many applications it is a joint not really interesting in boat building. The joint is weak and does not have any structural integrity, so beside the picture frame for the owners picture on board it is not used.
Now if joining two wood pieces corner to corner is necessary there are some other techniques you can use. First there is a method you can call split joint. Here you half the two pieces before joining.
Another method is to make a slot joint where one piece has a tap and the other has a slot. An important issue here is to make the joint with the right proportions so it get as strong as possible. The proportions should be 3-4-3 as shown on the figure below.
An interesting and useful variant of the tap and slot joint is one where the slot is replaced with a hole. This joint is a real decorative and strong connection. It is important to make room for the glue when making this kind of joints.
Beside joining boards like in picture frames you can also joint the boards like in a box. This is often used when making superstructure like cabin sides or cockpit sides. An important issue when joining the wood boards this way is to protect the end surfaces from weathering.
As you can see from the illustration not all end surfaces are protected. If you want that and believe me in the long run you want, you will need another method for joining the camin or cockpit sides.
The above illustrated method for joining the wood boards is really great when you want a durable, nice and strong joint. Here you also have the advantage of being able to make nice round corners without loosing strength in the connection.
One last connection in relation with the joints here is one that I can’t recommend using outside. This connection is mostly used when making drawers and it does not protect the end surfaces. Therefore it is a joining method only suitable for interior use. The method is widely used in industrial products because it is easy to make on machines and easy to use on uniform items.
This was a short list of some of the wood joining method used in boat building. Most of the methods have roots within carpentry and are as such developed during generations but some are developed especially for boat building and ensure nice and long lasting wood joints proven in generations.
Happy boat building,
Morten Olesen, Master Boat Builder and Naval Architect