Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Sunday, April 27, 2014

Installing Chines Part 2, Starting the Sheers

After doing the initial bending using the new steaming tool I continued cutting additional notches in the frames for the chine. The notches at the front of the boat (frames 4, 5 and 6) are cut at at a much steeper angle than those that are aft of frame 4. This makes sense when you consider the amount of bend that is necessary to get the chine down to the stem.

But determining that angle requires several trail runs on installation of the chine unless your some kind of a math wiz (I'm not!). Additionally, cutting these notches is harder than the others because they are "U' shaped notches rather than "L" shaped like the aft notches. There's insufficient room to get the saw in there to cut the bottom cut. I could have rigged up a routing jig, but this seemed like a lot of work for little payback and with three completely different notches, would have probably required three separate jigs.

What I end up doing and which turned out to be fairly accurate was to mark the extents of the cuts and then saw vertically down to them, making multiple parallel slices about 3/32 inch apart. This includes making a vertical cut at the very ends of the bottom edge.

Then using a chisel and hammer, I broke these smaller sections out. All that remained was to use a file and smooth out the cut. One additional thing I did was to cut the notches shallow (less than needed). This allowed me to judge my cut angles as well as the actual depth needed for the chine. You have to keep in mind that there must be sufficient remaining material on both the chine and the frames for fairing away.  Each notch is different so this is more of a matter of trial and error than anything else. As you get closer to the final depth and angle you make smaller cuts.

The chine had to be steamed more to get get it to lay into the notches in frames 5 and 6. If you look closely, you can see the way there is material on the frames that will need to be faired away to match the front curvature of the hull.

Once I had the chine into these notches, I needed to tackle the final bend down to the stem. This was very difficult to accomplish because the remaining piece of lumber was short which provided inadequate leverage for bending. Even with lengthy steaming, it was difficult to force the part down to the stem. I did manage, but I knew that there was going to be a lot of strain on that part.

After making this bend I also realized that I needed to increase the angle on the notch in frame 6. Also required was cutting the end of the chine to match up flat against the stem.I made an initial cut using the stem as a rough guide. The cut needed to be parallel to the stem horizontally and vertically. Because of the clamps I needed to hold the part down, I couldn't make the cut with the chine in it's bent position. I had to mark the cuts and do them after releasing the part.

You can see in the previous picture that I didn't get this quite right. Also notice the way I was trying to clamp on the angled chine. This was also not satisfactory and required a small piece of wood screwed into the chine to give the clamps something to hold on to.

Fortunately, I have the Glen L Builder's Forum to go to and as is almost always the case, someone had a better idea on clamping. In retrospect, it seems obvious, but I failed to see it until it was pointed out to me. One of my concerns when trying to clamp the chine down is that I didn't accidentally force frame 6 out of position. It's pretty solidly glued in, but I didn't want to take a chance.

The clamping solution was to lay a 2 by 4 board on the back side of the frame so that it was roughly parallel to the chine. The board stretched between the stem and frame 6. Then using two clamps and alternately screwing them down. I was able to clamp the chine up to the stem quite easily.

The previous picture shows the chine angle at the stem already cut correctly, but it wasn't that way initially. The same builder who gave me the advice on clamping also suggested I use a thin piece of would laid up against the stem. It needed to be slightly thicker than the widest part of the gap in the angled cut. Then using the wood as a guide, I sawed down through the chine using my Japanese razor saw. After that the cut looked like it does in the previous photo. (Thanks Skip!)

Of course, cutting away this material at the front meant that the chine had to be shifted forward. The angled cut needs to be the correct distance back from the the forward edge of the stem so that when the stem is faired to an angle, the angle will run directly into the chine. Imagine a line running parallel to the outer edge of the chine out past the forward edge of the stem. If two lines are imagined, one for each chine, they should meet over the center of the stem forward edge.

Fortunately, there is an easier way to determine this. A simply tool cut from a piece of scrap wood can be set on the stem and indicate if it's far enough forward or backwards to be in the proper position. The following photo shows this tool and how it's used. The small leg on the left lines up with the centerline of the stem when the chine is in the correct position.

As mentioned, the chine has to be slid forward a small amount to get the chine angle up against the stem. This is why I left the part long at the aft end of the boat. Once I had the chine / stem angle correct, I could go back and trim the aft end of the chine to the final length.

All that remained was to glue the chine into position. I had to do a small amount of final tweaking of notches before doing this. That was quickly accomplished. The chine is held in place with epoxy and 2 inch #10 bronze screws. These screws need to be recessed below the surface so that they don't interfere with fairing later on.

The process of attaching the stem was straightforward. Apply some unthickened epoxy to all mating surfaces, then thickened epoxy, then clamp into position, drill and recess the screw holes, and add the screws. I didn't do all this at once, but rather attached the aft three frames first, then the middle two frames, and then finally the two bow frames. At each step, the chine was left to spring to it's natural position except where it was being attached. This made it easier to get the chine into the correct position at these attachments. I also delayed adding the epoxy until just before I needed to attach the chine to a particular frame. I supported the loose end of the chine (at the bow) on a roller stand.

The first chine is now glued into position and will be ready for fairing when I get to that point.

This has considerably stiffened the structure. I am beginning to have a real appreciation for the overall strength of the design. Once all these longitudinal pieces are in place and the skins applied, the hull should be quite strong.

While waiting for the chines to steam, I also started working on the sheer battens. These are the longitudinals that run the length of the boat at the top edge of the frames (closest to the floor right now). The challenge I face with these parts is that they also need a severe bend at the bow end. To get them into the initial bend they need to extend quite a bit out to the side. You can see that in the next photos.

However, there is insufficient room on the opposite side of the boat to perform this bend. So what I will be doing is doing a pre-bend of all the sheer pieces (two per side) on thee same side (where I have more room to work with). Final fitting can then be performed on the opposite side of the boat for those pieces.

Pre-bending was accomplished using steam and some clamps. As with the chine, I had difficulty with clamping he forward end of the sheer to the stem and breasthook. I have a temporary arrangement that works okay for steaming and bending, but I will need a different arrangement for gluing so that the entire gluing surface is clamped into place. I have a plan for this clamping arrangement which I will detail in a future posting.

In order to bend the sheer I first needed to add the sheer notches at each frame. This is not an easy task for me because it requires lying on my back and making the cuts. I have a problem of nausea when lying on my back so the cutting was a slow process. But eventually they were cut. Like the chine notches, those at the bow end are cut at steeper angles to accommodate the bend.

Once the sheer was adequately steamed (about 50 minutes because the parts are much thinner), I quickly bent and clamped it into position. Here are some pictures of the process.

The sheers are made from two laminated pieces of lumber on each side of the boat. So all four pieces will need to be bent. Also, because the lumber is not long enough, I will have to add additional length by using a scarf joint like I used for the chines and keel. I plan to do that after the pre-bending is done. I did it this way so that I wouldn't have to try and accommodate extra lumber length during the bending process.

So far I only have one sheer pre-bent as I have been concentrating on the chines. I still have one more chine to install so that will be accomplished first. When I make the next posting, hopefully I can write about the completion of the chines and more work on the sheers.

Until next time, take care.

Update 9/14/2014:
I have been fairing the hull for nearly four months and one area that has given me a lot of trouble has been the forward bends of the chine. In hindsight, the steaming of the chines allowed the wood to bend in a different manner than would have been best for the boat's shape. Ideally, the chines should have been installed at the front first and then bent around to the transom. Using gradual motion and maybe some heat, I could have gotten a better more fair curve in this area forward of frame 4. Lack of space in my garage prevented me from doing that and I had therefore chosen the steam method and worked my way forward.

Because of that, the chines were too low and a bit too flat. This required me to add shims to the exterior of the chines in this area in order to get a more fair curve.

Anyone contemplating this build or a similar boat should allow themselves the room to accomplish the chine installation as it is outlined in "Boatbuilding With Plywood" by Glenn Witt in order to avoid the problems I ran into. In the end, I was able to correct the mistakes and the boat will be okay.

Wednesday, April 16, 2014

Bending The Chine

Bending the chine to curve around the bow of the boat is one of those tasks that I've been looking forward to and dreading at the same time. The thickness of the chine alone is cause for concern because wood that thick generally won't bend enough to get the degree of curvature I needed.

Additionally, I had to cut the notches for the chine in frames 5 and 6, which are the two frames I spent quite a bit of time dressing up last summer. These notches are also more difficult than the straight notches cut at the back of the boat,

These concerns have made me worry about this process for some time. Granted it's only wood and if worse came to worse, I could fix most any problem that arose, but I really don't want to have to do that for two reasons. The expense of replacing the wood and the very real hassle factor of fixing parts that have already been completed. And of course, there is the damage to my pride that would occur.

Nevertheless, this is a necessary task and I now have all the tools and equipment needed to make the bends. I have started down this path and will continue for the remainder of the week. This article will cover the first part of this process.

In order to accomplish the bend, I could have attempted two different techniques.The first technique is to wrap the area to be bent with towels and pour boiling water over them and gradually bend the wood into position. This approach has a few drawbacks. First, it is messy. Secondly the wood is not heated very thoroughly so the amount of bend that can be accomplished is smaller, meaning that more water will have to be used.

The second technique is to use steam. This requires a source of steam and something to contain the steam while it heats the wood. The traditional approach is to build a steambox and heat soak the wood  in the box. When ready to bend, you quickly transfer the wood to the area needed and apply the bend necessary.

One of the challenges I face is the limited space to accomplish this work. A real challenge is how to contain the steam around the bend area and still be able to get that container off of the wood before bending. I had thought of using a large PVC pipe but I have no room to slide the pipe off afterwards.

I recently ran across a different approach to steaming that seemed to offer an improvement on the process of using a steambox and answered the challenges I was facing with lack of space. This technique uses 6 mil plastic sheeting wrapped around the bend area. It has the advantage of allowing the continuous application of steam while performing the bend, thereby eliminating the problem of the wood cooling down too quickly. The plastic sheeting is also flexible and can stay in place while bending. And finally, it can be cut off afterwards.

So the first order of business was to acquire a source of steam. I considered a propane burner and a variety of steel containers, I even looked at a turkey cooker. But most of those were impractical either because of cost or safety (the cooker). sells a steam bending kit manufactured by Earlex that appears to be adapted from a similar product sold by Home Depot for removing wallpaper. It consists of a plastic reservoir with a heating element and a 10 foot length of plastic hose to connect to your steambox

Also in the previous picture, you can see the 6 mil plastic sheeting I bought from Home Depot. I am not sure if a thinner plastic would hold up using this steaming technique, so I bought 6 mil. However, the smallest quantity I could find was a 25 foot by 10 foot roll. Quite a bit more than I need but I figure that I can eventually use the plastic sheeting when I begin sanding and need something to keep sanding dust off of everything in the garage.

I began the process by cutting out a small piece of the plastic that was big enough to wrap around the chine.You need sufficient extra material so you can fold it over and staple the envelope shut. I folded the edges over a couple of times and used ordinary household staples every couple of inches. I didn't want the envelope too tight because I needed to put the steam hose into the end and also have room for the rags to block off the ends.

The rags were folded over a few times and then wrapped around the chine. The bag is slipped over the rags on both ends. This will keep most of the steam inside the envelope. To keep the hose from falling out, I simply tied it in a couple of places to the chine.

Then fill the reservoir with water and hook up the hose and electrical connection. It took about 15 minutes to get the steam going. One other thing I did was to place a bucket under the lower end of the envelope to catch any water that drips out.

The rule of thumb for steaming is one hour for each inch of thickness. I let the chine steam for 2 hours to be sure. The reservoir of the steam generator is not big enough for two hours, so I had some boiling water on the stove and refilled the reservoir when it got low.

A word or two of caution here. Steam is very hot and you need to be very careful when working with it. When I refilled the reservoir, I turned off the steam generator and unplugged it. Then I waited a minute or two to let the pressure subside before opening the cap. I then slowly poured the boiling water into it and wiped it down before reconnecting the electricity. The down time was less than 3 minutes before the steam was going again.

After steaming for a few hours, I used a ratchet strap to pull the chine down to frame 5. It bent quite easily. However, the notch in frame 5 had not been cut yet so I had to let the chine cool over night with the ratchet strap in place before I could continue in the morning. This notch gets cut at an odd angle so I am going slowly with this. Also, the amount of bend needed to get the chine into the notch and down to frame 6 (as well as to the stem) will require a few more steaming sessions. I'll be cutting the notches as I go and bending a bit at a time.

You can see in the last picture that the notch still needs to be cut more, but I have to wait until the chine has dried out before removing the strap. Even with that , there will be some spring back of the wood, but it will be easier to get to that point and move to the next.

So far, the technique has worked as I hoped. I can bend the part while the steam is still being applied and it is quite easy to remove the plastic afterwards to let the parts cool and dry. I will be continuing the process over the next several days with the goal of having the chines ready to install by the weekend.

Until next time, take care.

Update: 9/14/2014

See the update in the next blog entry after this one for more on the results of this steaming of the chine.

Sunday, April 13, 2014

Chine Work, Quick Update

Yes, I am still alive and still working on the boat. I am waiting for a steam generator I purchased a few days ago which should be here by Tuesday and then I can begin the final fitting and installation of the chines.

I have scarfed and glued the second chine block together and cut some additional notches. The first long chine is in place on the frames but waiting for the steamer so I can make the first sharp bend.

I'm on vacation this week so I want to make some serious progress on the chines, (hopefully installed). After that, I'll be starting on the sheers.

I don't have any pictures to add at the moment so I will wait until I can report on something more significant to post something.

So that's about it for the moment.

Saturday, April 5, 2014

Fitting The Chine Blocks - Part 1

The chine blocks (or simply chines) connect the middle frame corners of the frames together. They provide a place to attach the outer skin at the junction between the side of the boat and the bottom. They are also a major structural member of the boat and therefore require lumber that is quite thick, in my case 1 and 1/4" inches thick.

The other thing about the chines are that they are curved to match the shape of the boat. They start out fairly flat at the aft end of the boat but gradually curve inwards as they move forward. By the time they reach frame 4, the amount of bend is getting to the point where any further bending will be difficult to do and would most likely break the lumber. From frame 4 through frame 6 the bend gets even more severe  and then the chines attaches to the stem at the bow.

I plan on using steam on these parts of the bend which should soften the wood sufficiently and make these severe curves possible. But before I can get to that point I have to fit the chines to the frames at the aft and middle sections. That is what I will be covering in this article.

First off, I want to make a correction to a statement I made in the last article. The following photo showed the chines temporarily;y setting in the transom frame and I indicated that the chine would be faired away on the top edge and sides to match the frame contours.

This is incorrect. The chines do have to be faired away on the bottom edge  but they should be mounted to the frames in a manner where the chine sides are approximately parallel to the frame sides. So in the previous photo, the chine would need to be rotated counterclockwise some until it's long side is the same as the transom side. You can see that in the next photo near the foreground.

What you want to do is trim the frames to match the curve of the chine, but the outer chine surface should be relatively flat so it provides a mating surface for the plywood skins. The next photo shows how frame 4 will eventually need to be faired to match the curve of the chine. The curved chine is horizontal in the photo and you are looking down on frame 4. You can see how the frame sticks out beyond the chine.

Each frame needs to get a custom notch cut into it's corner to match up to the chine. The angles of the cut must match the angle that the chine intersects the frame. The previous photo shows this, however, that notch is still not quite right and needs to be trimmed more on the right side.

The way I tackled this was to start by temporarily clamping a shorter piece of stock in place to get an approximate idea of how the angles looked.I marked these angles and then proceeded to cut out the first notch. When doing this, you want to proceed slowly and cut the notch shallow. 

The process is, make an initial cut, fit the chine into position and see what corrections need to be made, then cut a little more. Fit again and make more cuts. Repeat this until the notch is correct. Each time, be careful not to cut too much material aware from the frame. Be cautious and go slow. Also be aware that as the chine lies further into the frame it's relative depth in relation to the frame changes. So it is quite easy to over cut the depth of the notch.

What you want to end up with is the outer upper chine corner higher than the frame and the inner upper chine corner slightly higher or even with the frame. You can see this somewhat in the following photos.

The cool thing about the chines are that when they are in position, you can actually see the shape of the boat. The next two photos show this. You can also see that I had to use ratchet straps to hold the chines into position. You're looking for a nice gradual curve as the chine moves from frame to frame.

To give some idea of the bend needed at the bow, I took the next couple of photos. The pictures don't show it real well, but  you can get some idea of what will be needed. The first photo shows the chine still needs to be bent more to even touch frame 5. In the second photo, frame 6 is in the foreground and the chine would eventually have to bend to meet this as well. Forward of frame 6, it curves even more to meet up withe stem at the bow.

You will probably notice in the previous photos that the chine does not appear to be long enough. This is correct. That piece of lumber is 17 feet long but the chine needs to be approximately 22 feet long. This will be accomplished with a scarf joint like I used with the keel. I have already performed this on one of the chines.

The next photo shows the sharp angle needed for the scarf joint where the two pieces of lumber are glued together to forma a longer piece. This is approximately a 5 degree angle which gives approximately a 1:12 gluing surface for the thickness of these pieces. I cut this angle using a router and the scarfing jig I made several months ago for the keel. I had to change the angle pieces on the jig for these parts because the keel was cut at approximately 7 degrees.

The length of the chine is too long for my garage so I had to glue it up outside. The glued up pieces are actually about 24 feet in length so I have extra material to work with as I fit the chine. The scarf joint needs to be in the aft end of the boat between frames. So I will have to trim extra material off the lumber as I do the final fitting.

After the epoxy cured sufficiently, I had to place it into my garage kitty corner until I am ready to do the final fitting and installation. Needless to say, having to work around this is a pain in the neck. I have already bumped my head on this at least four times. It would be nice to have a larger shop to build in.

The epoxy on this scarf joint should cure for at least several days to ensure maximum strength. As I start making the bends at the bow end of the chine, there is going to be stress on the scarf joint at the aft end. I want to insure that it does not come apart. I had to be extra careful when gluing this up so that there is sufficient glue in the joint and the joint is nice and straight.

So next week, I am hoping to buy the apparatus I need for steaming. I still have to glue up one more chine and both of them will need the glue cleaned up. I also have some tweaking to do on the notches and a few shims to make for slight over cuts. I will cover more of this process in the next posting. 

Take care until next time.