Fairing It Begins
Fairing has been labeled as the bugaboo of wooden boat building. Its only natural to feel that way about this necessary task. You spend months, even years putting the hull structure together, only to take a sander or planer to it and shave part of it off. Theres the fear in the back of your mind that youre going to take off too much and ruin all that work.
But theres another way to look at it. After you have spent so much time getting the hull structure ready, it is still only a collection of parts until the skin is on. Only at that point could you actually put it in the water. Of course theres more to it than that, but the fact is, if you dont put the skin on, then you cant proceed any further and youve essentially wasted all that effort and money.
So fairing is a necessary step. What is fairing? For those readers that might not be familiar with the term, it is shaving down all the corners and edges that are preventing the skin from lying flat on the structure. The structure is a collection of parts made from square, rectangular, and angular pieces of wood. There are no curves unless they are cut into the wood. It is essentially impossible to construct the hull without some material sticking out in various places. This excess material needs to be removed.
Heres an illustration of what I mean. The frames in this photo (coming in from the right) curve down to the chine (the long part going away from the viewer). The chine is a rectangular piece of material laid into notches cut into the frames. In order for the skin to lie flat on the bottom of the boat (the top edge in this photo), that edge of the chine sticking up must be removed and blended into the curvatures of the frames.
But theres another way to look at it. After you have spent so much time getting the hull structure ready, it is still only a collection of parts until the skin is on. Only at that point could you actually put it in the water. Of course theres more to it than that, but the fact is, if you dont put the skin on, then you cant proceed any further and youve essentially wasted all that effort and money.
So fairing is a necessary step. What is fairing? For those readers that might not be familiar with the term, it is shaving down all the corners and edges that are preventing the skin from lying flat on the structure. The structure is a collection of parts made from square, rectangular, and angular pieces of wood. There are no curves unless they are cut into the wood. It is essentially impossible to construct the hull without some material sticking out in various places. This excess material needs to be removed.
Heres an illustration of what I mean. The frames in this photo (coming in from the right) curve down to the chine (the long part going away from the viewer). The chine is a rectangular piece of material laid into notches cut into the frames. In order for the skin to lie flat on the bottom of the boat (the top edge in this photo), that edge of the chine sticking up must be removed and blended into the curvatures of the frames.
Of course it sounds simple in theory, but in practice, each frame curves down at a different angle, which means that the chines edge that is flattened out, will gradually increase in angle as you move towards the front of the boat. The edge will need to follow a gradual change in angle over its entire length. It gets even more dramatic at the bow. I havent actually figured out how to do that yet, so I will refrain from discussing that part of fairing until I do understand it better.
At the back end of the boat, on the sides, it is relatively flat and very little fairing is required. On the top edge of the sides, there is another rectangular piece of wood that needs to be blend into the curves of the frames (the sheer edge near the floor).
To start out this process, I needed a confidence booster, something to warm up on.This is the top edge of the chine as seen in the previous photo. But only on the aft end of the boat, because the front end requires a different technique.
You start by filing away material directly in line with the frames, blending it into the curve of the frame. The next photo shows this.
When youve done the frames in the flat aft area of the boat (frames 3, 2, 1, and the transom on my boat), it looks like the next photo. You can see how the chine has been blended into the frames at each frame point.
Next, you connect the blended areas with a line along the length of the chine. You can see that in the previous photo. This line represents the future edge of the bottom surface. I wasnt going to sand this down all the way just yet. But I did want to sand it back some so that when I started fitting the test piece of plywood on the sides, this edge would not interfere with the fitting. So I sanded it back at a shallow angle down to the line I drew. You can see that in the next photo.
The edge looks a bit wavy, but thats more of a trick of the camera than anything else. The sanded area is fairly close to the line I drew. If you look at the closest frame in the previous photo you can see the triangular cross section of the remaining part of the upper edge that will eventually be removed.
There are of course different ways of doing this, and the technique I am using is what I feel comfortable with. But my intention is to start on the sides first and go back to the bottom (the top in this photo) later. You can see that the chine already blends into the frames on the sides fairly well. In fact, it only required a small amount of sanding to blend in.
At the transom, the frame on the side is a bit low compared to the chine. I filled this in with thickened epoxy and then sanded it smooth and blended the entire edge with the chine.
The way that the side is faired (only at the aft end of the boat for now) is to use a piece of plywood the same thickness as the skin and lay it up against the frames to see how it matches up, Sanding is used to even out the edge. What you are after is a nice fit between the structure and the plywood. This is illustrated in the following two photos.
Eventually, the real skin will be attached to the chine and sheer (and the transom frame only) with epoxy and screws. For reasons Ill go into at a later date, you do not screw the skin to the frames, however it is okay to glue them. In the last photo, you can see that the fit between the transom frame and the test plywood is pretty good. What you cannot see in the photo, but which I had to take care of, was that the angle of the transom frame edge was off a bit and the forward side had a gap in a few places. Some touching up with the sander, and several tests with the plywood, were required before I was satisfied with the fit.
Ive repeated this process at each frame up to frame 3, testing and light sanding until the plywood lays nice and flat along the edge. I also will need to look at the top edge of the sheer and the lower edge of the chine between the frames. I am not sure yet how I am going to do this. I can either test using a wider piece of plywood or get it close at the frames and then blend in between them in long continuous strokes with the sander. As I mentioned, I am not yet sure how I am going to do that part.
At any rate, that is the state of my fairing. One other part of the build will need to be accomplished before I can do too much more fairing (at least at the front of the boat). Because of the angle of the hull curvature and the bow is quite sharp, a considerable amount of material is going to be removed from the sheers near the floor. In fact it will go from a rectangular cross section to a triangular cross action before its all over with.
In order to maintain the strength of the sheer in these areas, it is necessary to laminate another piece of lumber on the inside of the sheer between frames 4 and 5, 5 and 6, and 6 and the breasthook. So I will be doing that over the next several days in addition to repeating the fairing Ive done already on the other side of the boat.
After that then I am going to start trying to figure out how to fair the front of the boat. The bottom of the boat will be faired last. Than includes fairing the keel with the frames in a similar manner to the fairing of the chines. And there is also the stem forward edge that will need fairing so that the edge of the skins has somewhere to attach to. All of that will be covered at a future date.
So until next time, take care.
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