Cove and Bead Strips on a Night Heron
Starting a New Build
I'm starting on a Night Heron. This one is being made with 3/16" western red cedar strip. I'm using cove and bead strips this time to help make the build go a little faster. I'm not bothering to book match and I am stapling. In otherwords this is a pretty vanilla build. This video is mostly time lapse with detail interludes showing some of the techniques I'm using in more depth.
I started out with the sheer strips. I find with the Night Heron that using a narrow strip for the first strip is easier for making the bends up at the ends. I've used wider strips and tapered them at the ends some times, but here I just went for a consistent width. Since I had previously shaped a cove and bead on all the strip I needed to remove the bead (the convex, rounded edge) so there would be a flat edge between the deck and hull. This makes it easier to get a clean tight joint later when I rejoin the deck and hull after glassing the inside.
I removed the bead with a hand plane. A couple strips taped on to the bottom of the plane serve as a guide to automatically stop planing at a predetermined width. I clamped the strips to my work board next to the forms and planed until the tool stopped cutting. The strips will be installed with the cove (hollow groove) side up.
On the boat the strips need to be beveled to make a miter-like joint between the deck and hull. I clamped guides made of scrap strip to the forms such that they bisected the angle between the deck and hull. These served as references for the bevel. At the middle of the boat the bevel is 90° so the planing to remove the bead is enough. Near the ends the angle becomes more acute. You can view my video of installing the sheer strips on the Petrel to get more detail.
Once the bevels are made, I just stapled the strips in place. I usually staple every 2nd or 3rd strip initially to check that the wood bends in a smooth curve and then add the rest when I get everything fair. Since the strip is narrow I just shot one leg of the staple through the strip with the other leg hanging below.
The Second Strip
The next strip gets installed right on top of the first, but instead of bending down to follow the sheer, I let it run straight at the ends. I allow the wood to follow its natural curve to the stem. Since none of my strips are full length I cut the end off using a little miter box I created so when I continue the mating ends will match. I apply glue in the cove of the first strip where the second strip will touch. In this video my glue dispenser has too big a hole in the tip and is applying more glue than I would like. It only takes a 1/16" (~1 mm) bead of glue to do the job. I should really get a new tip for my glue bottle.
Installing the Strips
Cove and bead strips can be a little tricky to get tight. They can look tight from the outside, but if you are not careful there may be a gap that appears when you sand away the outer surface. To help prevent this I wiggle each strip before I staple down. This helps displace the glue and assure the seam is tight. After the wiggle, press the strip tight down against the form, maintaining pressure down into the previous strip and shoot a staple through the strip into the form.
I'm using 9/16" long standard "T-50" staples. I shoot them directly through the strip into the form so both legs of the staple go through each strip. I find that these staples will naturally stop with the cross bar just above the surface. This is good because it means they will be easier to pull out later.
Stripping the Side
Once the first two strips on each side are installed, you have a brief time of fairly quick and brainless stripping. Dry fit a strip, take it off, add glue to the cove of the previous strip, add the new strip, staple it home, repeat. Keep on adding more strips until you get to the chine, this will usually also correspond to when you get to the "knuckle" of the stem at each end of the boat. A the point you will transition from strip up the side to across the bottom.
With the Night Heron, there is a fairly distinct chine. If you are lucky you may find that the angle at the chine is right at the top of the last side strip. In which case you may be able to just fit another full width strip on the bottom into the cove of that last side strip. This almost never happens for me, and it is easier to to get over that transition by installing a narrow strip. I used a 1/2" wide strip here. I used some tape to help hold the narrow strip tight all the way along it length.
The Ends - Cheater Strips
So far I neglected the ends between the first strip and second. This is where the "cheater" strips go. Since I have tape over the chine strip, it is hard to keep on going on the bottom until the glue dries. This is a good time to deal with the neglected ends. The end of each strip here needs to be tapered to fit into the space left between the existing strips. The first of these is the hardest because the taper fades away to a very skinny space that must be filled with a delicate piece of wood. I mark the approximate length of the taper and then plane away the wood that doesn't fit. Working on the bench helps support the flexible strip as I plane. The edge that you are planing away will fit into the cove of the sheer strip. To make a tight joint you will need to make a bead on this planed edge. Just use your block plane to knock the corners off the square edge and then a couple quick strokes to knock the corners off the corners and you should be able to make a pretty good approximation of a bead.
The Bottom Part One
After the glue holding the chine strip dried I could work across one side of the bottom. I let the strips hang long enough to fully cross the center-line. This is pretty quick and mindless: dry fit, remove, add glue, install strip, press it tight, staple. Make sure the strip extends beyond the center-line. If you mess up, glue in a short piece to make up the distance.
Trim the Center-line
The excess needs to be cut off at the center-line of the keel. I use a jig to transfer the center-line marked on the forms to the outside of the strips. You can watch my video of trimming the keel line on the microBootllegger for more detail. I connect the dots with a strip, then saw off the excess a little beyond the line and then use a rabbet plane to get right down on the line. At the ends I used a chisel a bit to make it easier to get the first few strips in on the other side.
The Bottom Part Two
Your skills developed in fitting the cheaters will now be used on the bottom. The ends of the strips need to be fitted in against the flat planed edge of the center-line. You will not need to make a bead on these taper because the center-line is plane flat. Both ends of each strip will need to be fitted. Instead of trying to fit the length perfectly by adjusting the tapers, I fit two separate strips, one for each end, and then join them together in the middle with a butt joint. The measurement of this butt joint is easier than getting the tapers accurate. Just cut the butt on one strip with the miter box, glue in that strip and dry fit the second end in place and mark the length in place. Use the miter box to cut appropriately and glue/staple the second end in place.
Eventually you will get to the last few strips. Because of the cove, the space to be filled will be larger than the hole that you can see. If you were to try to keep the cove on the second to last strip, the last strip would be impossible to install. So I cut the cove off the second to last strip with a block plane. This leaves a square edge on both sides of the closing strip. Now I can cut the bead off the last strip and scribe in the shape for this strip and carefully plane it to fit. Watch my video for the Petrel for more details on the closing strip. I wrapped strapping tape across the center-line as I went to make sure the keel seam is tight.