Wooden Boats 101

This is designed to be a short introduction to the basics of wooden boat building and restoration. It will start out with the basics, such as types of boats, hull types, frame types etc, then will get more in depth. These pages are a work in progress and should be considered incomplete. There is more information that should be included. For example, stitch and glue is still a relatively new form of construction and should be included here. They do however present a good introduction as intended.

There are three basic types of boats. The first is Human powered (e.g. rowed or paddled), The second is wind powered (sailboats), and the third is motor powered. This seem simple enough, however, wooden boats can be broken down even further, into the methods used to construct their hulls. There are dozens of methods, but I am going to concentrate on the 6 main ones- 1.Caravel, 2.Lapstrake (or clinker), 3.Strip, 4.Plywood Panel, 5.Tack and tape, and 6.Batten Seam.

Lets' start out with Caravel planking. Caravel planks are laid edge to edge so the finished surface of the boat is smooth. The planks must be precisely fitted, or they will leak. The planks are screwed to either sawn or steam bent frames (there is more on frames later). The seams between the planks must be caulked to assure their water tightness.Notice on the drawing to the right how the planks must be curved to match the desired curve on the side of the hull. This results in strange shaped planks that are extremely difficult to cut to shape, so this method is generally used only by the experienced woodworker. This style of planking is used on all sizes and types of vessels.

Next we will look at Lapstrake, or Clinker planking. Lapstrake hulls are made by overlapping the bottom edge of the plank over the plank below it, as shown in the drawing to the left. The planks are then attached to the ribs with either rivets or screws. The ribs are generally steam bent, although it is also possible to use sawn frames. The necessity of perfect joinery this planking method demands, especially in the stem areas, limits it to only the more experienced craftsman. The style is used in all sizes and types of boats.

The next type of planking is common to mahogany runabouts. It is one of the most difficult methods available- Batten Seam. Just as the name suggests, the planks are laid edge to edge, and instead of applying caulking between them a batten is attached to the back to waterproof it (see drawing, right).The battens and planking are then screwed on to sawn frames, sometimes with steam bent frames for additional strength. This permits the entire side of the boat to be finished 'bright", meaning stained and varnished. This construction style is difficult to do, costly, heavy, and not too strong, so beginners should shy away from it. It is used generally on smaller powerboats, but can be used on all types of boats.

All of these methods so far have not been suitable for beginners to the field of boat building, unless they are good woodworkers or they have received some instruction. However, the methods that follow were, for the most part, developed with the beginner in mind.

Plywood Panel construction is one of the easiest and fastest ways to build a boat. The entire side of the boat can be planked with a single piece of plywood, eliminating the need for complicated joinery. The plywood is then screwed on to sawn frames. Some of the smaller designs can be built in a weekend for less than a hundred bucks. This method is used on all types and sizes of boats.

A 'version' of plywood panel that is ideal for amateurs is known as tack and tape. In tack and tape construction, you cut out the panels, tack them with small nails as a temporary hold, and then go over the seams with epoxy and fiberglass tape. Some builders also encase the entire boat in epoxy for additional protection. The strength does not come from frames, but from 'fillets', which are simply epoxy putty formed into the joints. This allows the builder to eliminate some of the frames, saving on weight. It is an expensive method, however, due to the cost of epoxy. It can be used for any type of boat up to around 30 feet, but is ideal for small boats.

The main problem with the plywood panel methods of construction is they limit you to more or less straight sided designs. For curvy hulls, amateurs can use a method known as Strip Planking. Strip planked hulls are... well.... planked in strips! (imagine that!). The strips are made thin (around 1"x1" somewhere), so extreme curvature is not a problem. The flexibility of this method makes it popular for kayak builders, as it is easy to reproduce the complex shapes of the vessels.sometimes the builder will choose to route the strips, so one side of them is concave and the other is convex (see drawing, left). The strips are epoxied in place, with nails or brads holding them until the epoxy cures.This is used for all types of boats. Ideal for small boats.

This concludes our lesson on hull types. Let's take a quick look at frames. I am going to show you the two most common types- Sawn and bent.

Sawn frames are built in one of two ways. The first is illustrated on the left hand side of the drawing (right). It depicts a frame built up from three pieces of wood, screwed together on the corners. The second is on the right side of the drawing. This is made from a single piece of plywood, sawn into shape. This is easier to do for smaller boats, because you don't have to worry about fitting several pieces together. You can't use sawn plywood frames on big boats, however, because plywood is not thick enough to take the strain.

Laminated frames also deserve mention, although they are a type of bent frame. They are made by laminating several layers of wood together in the desired shape, effectively creating plywood that is laminated with a built in curve.

The other kind of frame that is commonly found is steam bent. A steam bent frame is usually made of a hardwood for strength. As the name implies, they are bent after being heated with steam. Steaming them makes them far more flexible, so they can be used on complex curves.

So you now know the basic hull construction methods, and frames that are commonly used. But, How does the boat actually become a boat??

The boat must be assembled on a backbone, called a keel*. This holds the frames together in the desired shape, so the planking can then be screwed on. But, this is not the only reason for the keel- It is also the most important structural member for the boat after it is built. The stronger the keel, the stronger the boat (generally). Boats are usually built upside down, unless they are very large. The keel is built first, then propped up on a strong-back, so it will be kept upright and at a suitable height for the builder to install frames and planking comfortably. The frames are then attached to the keel, and temporary supports are added to various parts of the boat, to hold everything in the desired shape for construction. After all of the frames are in place, the planking process begins.

  *alas, to make things more complicated, there are several boat types that do not use a keel of any sort. Perhaps most notable of these is the Dory, which uses the strength of the bottom planking itself in place of a keel structure of any sort. In addition, several of the modern building types, such as stitch and glue & plywood panel, do not have keel structures (many do not even use frames).

But, we are already getting ahead of ourselves. The keel deserves more than just a mention- it is among the most important parts of a traditionally built boat. Why do I say traditional? Well, the modern tack and tape and lamination methods of building have made it entirely possible to build boats (small ones at least) that lack some or all internal bracing. Examples that stick out are the well know Phil Bolger designs. The smaller ones completely lack internal support- they get their support from the curve in the plywood and some external members, which are nothing more than some pieces of wood bolted on to the outside of the boat. There is a boat sitting directly underneath me now (it's in the basement) that is built in such a manner- it has no internal frames.
 

So. why bother with frames at all when a boat can be built without them? after all, it leaves a lot more room on the inside of the boat for people and gear..... But, as boats get larger, the loads demanded on them increase. in addition, long expanses of plywood tend to flex a lot more than small pieces do, when you combine this flexing with high loads, you get breakage.... and, in turn, sinkage......
 

I am not going to go in to the particulars of how much bracing needs to go where on what kind of boat. That is best left to the experts- let them do the math for you. When you build a boat from a set of plans, the location and size of all frames should be noted on the plans.

Ok, so now we have the keel in place, and the frames attached to it. So, what's next? Stems and transoms. Hold on, you say, that should have been earlier! well, on most boats, yes, but what the hell let's just put it here. On a traditional boat, the stem is just basically an extension of the keel that defines the shape of the bow of the boat. There are some exceptions to this, but for all practical purposes this is true. The stem is a very important part of a boat, as it serves as the forward attachment point for the planking, in addition to providing structural support to the hull and deck, so it is built strong. Take a look at the stem even in a small boat, it will be of good size. Keep in mind, the stem is at the extreme forward end- everything the boat hits (water when running, docks, other boats, icebergs, etc) will be most likely hit in the stem. For those of you interested in modern construction styles, you will be interested in knowing that the majority of 'high tech' constructions, including many that are frameless, still have stems.

I'm rambling again. Lets get back on track. On the opposite end of the stem is a transom. it is the board, or boards more likely, that make up the rear end of the boat. The transom serves as both a structural member and as an ornamental member- wooden boats are likely to have beautiful varnished transoms embellished with the vessel's name. Double ended boats do not have a transom, There will be another stem at the rear, generally. Transoms are generally built tough, they take a lot of load, especially if you are in a following sea.