Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Sunday, June 29, 2014

Hull Fairing - A Small Illustration

I continue to perform the fairing process on the hull. It's a long business and requires a bit of getting your mind wrapped around areas. The overall process is simple in theory, but much more complicated in practice. It can be quite overwhelming if you think of it in its entirety. More than once, I've slipped into a funk thinking of the amount of work and wondering how I was going to accomplish this task.

One of the first things I realized was that like any complicated endeavor, it's best handled in small doses while keeping a portion of your thinking on the big picture. For me, what works best is to pick a small task and then focus on that to the exclusion of the remainder of the process.

What I mean is that I am going to focus on fairing a frame, not the entire side of the boat. Or I am going to fair the angle of the frame on the bottom at the sheer. Or perhaps sand a portion of the sheer back, but don't complete the fairing process in this area.

There are three benefits to this and one drawback. The drawback is that the overall process takes longer because I am not continually working on the boat. But the benefits are, first I don't get burned out and thus am more willing to tackle another piece later in the day or the evening. Secondly, these small tasks add up over time and the job gets done. Thirdly, and this is important; as I complete a section, the remaining amount of work become easier to visualize.

However, I also realize that all of this may be hard for viewers to visualize, so this posting will be about illustrating a small piece of the fairing process.

First, understand that fairing is about removing all the excess wood from the construction that will get in the way of laying the planking (skin) flat on the structure. The boat hull is made from rectangular pieces of lumber, but is a curved structure. This means that invariably, there will be places where an edge or a corner is sticking out somewhere. The next two photos illustrate this.

In this first photo,, you are looking down on frame 4. The chine is on the left and has been partially faired on its upper surface to match the frame angle (not seen in this photo). The chine is transitioning through this frame at an angle as it travels towards the bow of the boat. To the right of the chine, a portion of the frame is sticking out (circled). This piece sticking out would prevent the skin from lying flat in this area.

In this next photo, the same area after fairing. The top edge of the chine has still not been faired, but the frame portion that was sticking out, has been sanded back to match the angle of the chine, forming a nice flat surface to which the skin can be attached to.

Here is another shot of the same area from a bit further back. It is quite easy to see how the chine and frame area is now faired as it should be. You can also see the upper portion of the chine that still needs to be faired to match the frame angle at the top left of the photo.

At the sheer edge of the boat, the process is somewhat different. Remember that the sheer is actually the top edge of the boat, but since the hull is currently upside down, it is closest to the floor. Like the chines, the sheer is connected to the frames and transitions though each frame at various angles. Nearer the bow end, the sheer takes on a dramatic curve and passes through the frames at a sharp angle. 

In the next photo, you can see this angle of the sheer in relation to the frame. The frame is represented by the small portion at the top of the photo. The sheer is the long piece going from the upper left to the lower right in the photo. You can clearly see the sharp angle of the transition. also notice the line drawn on the sheer. More on this in a moment.

Because the frames meet the sheer at such a sharp angle at the bow, a considerable amount of sheer material must be removed from the outer sheer edge. This is why I had to add additional sheer reinforcement to the inside surface of the sheers in the bow area earlier this month. The sheer will be cut at an angle to match the frame angles coming down. This is one of those areas that is difficult to visualize and is best handled in small doses.

I started by drawing a line along the top surface of the sheer to indicate how far the outer edge needs to be faired back to. There is no actual measurement for this in the plans. It is simply a fair curve that runs from the point on the frame where it must be faired to to the point on the next frame where it must be faired to. 

I used a  three foot long, 3/8" square piece of wood, formed into a curve and temporarily clamped into position to develop this curve. I was looking for a curve that was similar to the existing sheer curve because only the top outer sheer edge is going to be faired back. The bottom outer sheer edge will remain intact. More on this in a moment.

The sheer's outer surface should end up at an angle that approximates the angles of the frames coming down. I determined where the lower outer edge is by fairing away a small section of the sheer at the area of the frame. The next photo illustrates this on the chine and frame junction. The process is similar for the sheer.

The next photo illustrates the two extents of the removal area on the sheer. The arrows in the picture show the two edges. The two lines drawn thought the sheer are trying to show the angle that will be achieved after fairing.

After these extents are established, you begin by roughly removing material until you get close to the line and the outer bottom edge. Then you go slower and finish removing material until you end up with a nice angle that follows the curve of the sheer between the two frames.

In the two following photos, you see a portion of the sheer before and after fairing. Notice in the first photo how the line on the unfaired sheer (on the left) is back from the corner of the frame.The frame will have to be faired back at an angle to match this line on the sheer. It will then be at the same angle as the sheer in this area. What is significant here is that this difficult area to understand is now easier to visualize. This is especially apparent in the second photo. 

One final shot of the same before and after area. Again, you can see that it is easier to visualize the next area to fair away.

Another complicated area that I have not gotten to yet is the stem and the fairing required on its forward edge. This curved piece must have a constantly changing angle as you travel around the curve. When I get to that piece I will illustrate its fairing in another posting.

So I hope this helps the reader better understand what is involved in fairing. I will be continuing this process, one section at a time. Until next time, take care.

Friday, June 20, 2014

Excuses To Delay Fairing!

After my initial bout with fairing, I got a bit gun shy. I didn't want to make any mistakes fairing the structure. Was that really it, or was it because I am not thrilled with this part of the boat build?

Well, I think it's a bit of both, probably more on the not so thrilled part. Anyway, after having gotten part way finished with the starboard side, I was at a point where I was going to have to tackle the sheer at frame 4. This is the first part of the sheer where the curve towards the bow starts. It's the same with the chine. From this point forward, fairing is going to be more challenging and I am not quite ready mentally to tackle this.

Also, the sheer forward of this point is going to have quite a bit of material removed because of the angle downwards of the frames. The "Boatbuilding With Plywood" book by Glenn Witt states that it is often necessary to add additional material to the inside of the sheer between the frames in this area.

A perfect excuse to stop fairing!

So the sheer in this area has a curve which means that any material added here will also need to conform to that curve. I had some remaining sheer lumber left over, but not enough to do all the reinforcing. More on that in a minute.

I cut as many pieces as I could from the leftover sheer material to fit in these spaces. I left them long so that when the wood was bent, there would still be enough material. The reinforcements need to go from one frame to the next. A total of six pieces would need to be added. I had sheer material enough for four.

What I also had was some leftover scrap from two years ago when I cut out the frames. This scrap was 3/4 inches thick and I needed 5/8" thick for the sheer reinforcement. A few months back I had experimented with my table saw on how to cut thin slices off of wood. I was planning on using this technique to get the wood down to 5/8 inch.

The technique is simple really. You take a piece of wood at the correct thickness and place it between the table fence and the saw blade. The fence is cinched up to the wood. You can then run the thicker lumber through the saw and it is thinned down to the correct thickness.

Before I could do that, I had to get a usable piece out of the scrap, which was oddly shaped. I needed a straight edge on on side of the scrap in order to eventually cut the piece to the same width as the sheer material. I simply drew a straight line on the scrap through the widest portions allowing enough material on one side of the line for the necessary width. Then I clamped a wider board on top. This wider board already had a straight edge on two sides. One side was lined up with the drawn line. The other side would run against the fence and allow me to make a straight cut on the drawn line. The fence was set at the same distance as the wood clamped in place.

I'm sorry I didn't take any pictures of this particular process, so I hope my description is adequate. Once I had the wood to the correct width, I applied the technique for getting it to the correct thickness. This left me with sufficient material for the two additional sheer reinforcements.

The reinforcements were bent using steam over cinder blocks and using a ratchet strap to perform the bend. The following photos illustrate this process. The trick here was to get the bend sufficient enough to conform to the sheer when I glued it into position.

Gluing was performed in a similar manner to the second sheer lamination done a few weeks ago, namely using clamps.

After the bending was performed. I would temporarily clamp the wood to the outside of the sheer and draw a line to indicate the angle I had to cut the ends to match up to the frames. I would then cut outside of that line at the same angle and then gradually adjust it inward, testing the part on the inside of the sheer until it fit the way I wanted it to fit.

The end result after several days of steaming and gluing was six reinforcements glued between frames 4 and 5, 5 and 6, and 6 and the breasthook. The next two photos show before and after shots of the sheer between frames 4 and 5

This next photo shows the additional thickness.

Between work, steaming the wood, waiting for it to dry sufficiently, gluing up the parts , and waiting for the epoxy to cure, I managed to avoid fairing for a week.

But alas, I knew that I had to get into it or the boat would never be finished. So three days ago I started back up on fairing.I got the sheer faired from the aft end of the boat up to frame 4 on the starboard side as well as the remaining area of the chine in the same stretch of boat.

The piece of plywood is used to simulate the skin that will eventually be applied. I am pretty sure that when I start fitting the real skin, there will be additional fairing required so I'm just trying to get close at this point.

So far most of the fairing has been sanding the chine and sheer down to the same angle as the frames and then blending the area in between the frames to get a nice flat area to attach the skin. Forward of frame 3, the sheer starts to curve and the area to be blended increases as you get closer to frame 4.

To give myself something to guide the sanding by, I drew a curve from frame 3 to frame 4 on the sheer, gradually widening it to match up to the area already sanded down at frame 4. You can make out the line on the sheer in the last photo. The sheer is then sanded back at an angle to this line from the outside, leaving the bottom of the sheer essentially intact.

What I was trying to achieve is an angled surface on the curve that matched the angle that the skin will mount to the chine and sheer at. You can see that in the next photos.

Finally, today, I started repeating the process on the port side aft of frame 4. I still have more work to do here.

To illustrate one final point, the next photo is shot looking down on frame 4. You can see that the frame needs to be faired to match the chine on the left of the photo. The other frames forward of this are even more dramatic in the amount of material that needs to be removed.

Needless to say, the forward area of the boat has many angles and curves to consider while fairing and I intend to go slow in this area. So updates to the blog may be a bit farther apart for awhile.

Until next time, take care.

Tuesday, June 10, 2014

Fairing - It Begins

Fairing has been labeled as the bugaboo of wooden boat building. It's 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. There's the fear in the back of your mind that you're going to take off too much and ruin all that work.

But there's 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 there's more to it than that, but the fact is, if you don't put the skin on, then you can't proceed any further and you've 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.

Here's 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 chine's 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 it's entire length. It get's even more dramatic at the bow. I haven't 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 you've 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 wasn't 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 that's 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 I'll 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.

I've 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 it's 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 I've 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.

Sunday, June 1, 2014

Sheers Completed!!

This is just a short update. The title says it all. Last night I stayed up late and finished laminating the starboard sheer into position. Late today, I sanded down the excess glue. The sheers are completed except for fairing and possibly adding reinforcement later in the fairing process.

The longitudinal pieces of the boat have been a challenge physically for me and I am glad that it is done. The best part, of course, is that the boat has a definite shape now. The long pieces really define the shape and it's very satisfying to me to see all this come together.

So without further ado here are the few photos I have for this update.

The first photo shows the cut at the scarf joint for the second lamination. The first lamination's scarf joint is further aft between the next set of frames. I did not want the scarf joints on the two laminations to overlap each other so I moved the second lamination's joint further forward. This photo was before the scarf joint was made. Since I've shown this process before, I did not include new photos of that process in this update.

And these last two photos show the glue up in process last night. This was actually quite stressful as it was after midnight, I was tired, and it was still quite warm in the garage. The epoxy was kicking off fairly quick so I had to work very fast, hence the stress.

So I have a variety of small tasks to accomplish, mostly related to cleaning up glue and touching up encapsulation before I begin the next phase of the build, namely fairing the hull. I won't go into that process now but it is a lot of work required to get the hull ready for planking.

So that's it for now. Take care.