Building the 10 ft Nuthatch  
Design by Warren Messer - Seattle, Washington - USA

Part 1

Part2

I've been building so many boats lately, that I have to stop and think about which one I am writing about now. A peek in the shop shows that its the 10ft Nuthatch that I've finally gotten around to constructing after the PDF model has been posted here at Duckworks Magazine for over a year now. I think in the last story on building the PUD-g, I said I was next going to start work on a driftboat design I had. That hull has been put on hold for awhile so I can rethink the size of the boat and make a few tweaks to the design. But this story is about my first boats (the 8ft Nuthatch) bigger brother the 10ft Nuthatch. I also had several inquiries from readers as to when I was ever going to get around to building it. So here it is, and I'm going to spend more time with this series of stories on the details that can cause builders to throw down their tools and walk away from their boat building projects. This part will deal with the "big scary"in boat construction; scarfing plywood to make longer sheets.

I have to admit that the thought of having to scarf plywood breaks out the Costco sized bottle of Tums for a quick hit. But once I have set up everything, and start grinding away on the bevels, things improve. It's just a mater of overcoming the initial fears of a project. Like my first ever mix of epoxy, making the first fillet, or ever working with fiberglass. Baby steps turn into strides.

When I resized the lines from the 8ft to the 10 & 12ft versions of the Nuthatch, I made a decision to change one of the side panel edges from a straight line to an arc. This made a very big change in the looks of the hull even though it added some extra work in the lofting. But the extra effort in lofting makes for a hull with more appealing lines. I love holding the 10ft PDF model up on my finger tips and just looking at it. Enough day dreaming and on to building it.

I was conflicted on whether or not to use 5x10ft sheets of plywood again on this hull or bite the bullet and scarf. EdenSaw Woods made the decision for me by being sold out of the 5x10 sheets of Okume or anything else that might work. So it was time to practice my scarfing abilities again. Scarfing is one of those things that you have to work with a few times to become really good at. Not to say that a first timer can't do a good job; it can be done, but you have to be diligent in your approach. Dave Nichols wrote a great article on scarfing earlier this year for Duckworks Magazine. A good read and a lot of good information. I wanted to take one last stab at scarfing a full stack at one time, so I ordered my Anant A8 plane online. I wanted to have a tool long enough to cover the full face of the stacked scarf and the upper and lower guide supports, and maintain a "flat" surface. I had been using a router mounted on a beefed up piece of plywood that I ran up and down the scarf face. It worked ok, but covered my shop in a layer of routed plywood chips; and I mean covered. So I wanted to go in a quieter and less dusty direction, and so the big hand plane. I will keep using the plane, but will change my approach to scarfing as you will read later.

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One of the things I didn't do at the very start, was to reread my own directions on setting up the plywood sheets for scarfing. By that I mean, which side goes up. In my rush to use the new plane, and to cut the "partial extension sheets", I forgot which sides go up, and which sides go down in the stack. On a scarfed panel, the outside "tip" of the scarf points aft. Part of the planing is to determine the "good" side from the bad, and which you want to go on the outside. If you are going to have a wood finished interior, you want the good surface [with 1088 marine plywood this is can be a coin toss (mainly which grain pattern you like best)] on the inside. I am a confirmed painter, so I try to put the good side out; to give me the best surface for using high quality marine enamels and LPU paints. The hull's insides have a lot of glass taped edges, backing blocks, and hardware fittings that take away from any overall appearances. So I always go with good on the outside.

A keen Duckworks eye will see that I had all the sheets, good side up in the stack. The correct way would have the "longer" plywood sheets, bad side up, and the "shorter" sheets, good side up. Then when you epoxy the two pieces together, the short sheet flips over and both bad sides are up and the good side tip will point aft. The boat will still float no mater how you do it, so don't sweat the details. Worry about it on the next boat you build, and enjoy the one(s) you have.

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After the plywood sheets were squared up on the sides and set back 3" each, it was time to break out the new A8 hand plane. I did place some screws in a few places to hold down any edges that wanted to rise up. The screws were placed 3 1"2" back from the leading edge to protect the plane's blade. Having a level and flat surface to start with is necessary for good results. Any vertical curves in the plywood stack will become apparent when you attempt to epoxy the mating faces together, and see the horizontal arcs on the scarf edges. I also lifted the whole stack 1/2", by placing spacers under everything. I wanted to have a level and straight support for the plywood sheet at the bottom of the stack. The "extended and squared" support also gave me something for the hand plane to use as a lower guide, and some waste material to be planed down as the scarf bevel deepened. This support piece also helps keep the "thinning" edge from being blown out.

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So I set the depth of the plane's "iron" (lets be proper with names) and started with the first long stroke. Have you thought about how much wood I will be removing???? I hadn't ever thought about it before, but was soon to learn. I have to cut bevels 3" wide, by 1/4" deep on one side, with a running length of 16ft. That's taking a piece of wood 1/2" thick, by 3" wide, by 4ft long and planning it to oblivion. No wonder I was sweating after a few minutes, and I had to spread the sweat out over a couple of days. My arms thought they were in boot camp again after doing hundreds of push ups for no apparent reason, other than for the sardonic pleasure of the TI. I think Dave Nichols has the right idea about using the power plane.

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About halfway through the stack, I noticed that I wasn't making much progress on the top sheets in the stack. I discovered that I had my "upper support guide" set too close, so I moved it from 6" to 9" behind the edge of the top sheet. Then things were correct again and the bevel angle changed to what it was supposed to be; and work progressed towards completion. I noticed that I wasn't getting the straight line ribbons that you should expect if everything goes as planned (but I don't live in a perfect world). When I got to the point where the bevel started and stopped at the "correct" in and out points, I still had some waviness in the layers of plywood. Checks with a straight edge said things seemed correct, but it just didn't look right, so I marked those spots and did some fine tuning with my smaller hand plane. Things seemed to improve, but the straight edge checks said one thing and the eyes said something else. After some futzing around, I called it good enough. Things looked better, but I still had doubts.

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To keep from fixating on one thing and not progressing, I disassembled the stack and flipped the sheets around so I could sand and seal the end grain of the plywood. But before I apply the epoxy; I add a strip of 3" shipping tape along the scarf's upper and lower edges to keep excess epoxy from lumping up my good work so far. I then mixed up 1 1/2oz of SilverTip epoxy and brushed on all that the end grain would absorb, and it took most of it. The rest I used to epoxy a couple pieces of scrap plywood together to use for rail clamps. Always have something around that can use excess epoxy products. The panels ends were left to cure overnight.

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I removed one panel set from the work platform, and got the other set lined up to epoxy together. I clamp down the long sheet so I can do a dry fit to find the correct "overall length". With the short sheet placed so it is square and "level" with the long sheet, I clamp a stop guide at the end to mark this location. Then I'm sure that I can again find the correct spot to place the short sheet after the surfaces have been coated with epoxy.

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Now it was time to get out the System Three GelMagic and join these darn pieces of plywood so I can get on with building the boat. Scarfing is about as much fun as building the "true and square" frame for a traditional style of boat. I've been using GelMagic for all my bonding needs now, and it's the perfect product for this application. Mix it up and put in on, and it just sits there. On the sides of things, underneath something, or in a gap. Stuck like, Uh, glue.

The last time I had gone to the hardware store (my local "Do It Center") to look for a new 3" putty knife to use to fair in the edges along glass tape; I came across a "pointed toothed" plastic spreading tool. Hum mm, how will this do with epoxy? Great! I spread the GelMagic on the two scarf faces and the toothed spreader (smallest teeth 1/16") gave me a perfect and even coat along both surfaces. I didn't have to worry about dripping thickened epoxy running off either of the surfaces; even the one I had to turn over.

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Then a check to see that the short sheet was lined up back in it's proper place, and a straight edge check of the mating edges. Then a layer of plastic sheeting, topped with a "true" and straight backing plate, and a layer of sand bags to hold everything down. Time to cross my fingers and wait until the epoxy cured overnight. Then do it again with the next panel pair.

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After the dust had settled so to speak, I removed the shipping tape (with the excess epoxy I didn't have to scrape up) and looked at my handy work. Better than the last time, but not as good as the next. As I said at the start of this story, scarfing is an acquired skill, and to swim you to have to get in the water. I did some touching up to the exposed scarf tips, and added a layer of 3" glass tape to the inside seams of all the panels. On the outside the bottom panels get a layer of glass, and all the panels are strengthened by the EZ-Fillet and three layers of glass tape (two inside, one outside) at the keel and chine seams. The top of the side panels are stiffened by the rails. I've also changed the way I layout the panel pairs on the lofting drawings, so the bottom and side panel's scarf seams don't align with each other. That holds true now for my multi-panel designs; everything stair steps except the bottom keel pair.

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I didn't get enough GelMagic near the outer edges of the scarf seam, and had a couple of gaps. But after cutting out the panels, I had good fill along the exposed interior cut faces of the edges. To reach maximum strength, the very outer lengthwise ply, needs to be as continuous as possible across the scarf joint. A person might be able to get this by hand, but I think that only a CNC machine under controlled supervision could achieve this in the real world. A stressed (I mean really bent) scarf joint will always break along the outer seam; because of the discontinuous outer lengthwise ply caused by the cut across it's face. A layer of glass cloth (4 to 8" wide) added to the outer and inner scarf seams will increase the surface strength of the plywood for our real world needs, and can be easily hidden by a good fairing job. My best advise is don't sweat all the little details, just get on with it. Build your boat the best you can and go have fun. Don't worry about what others say. "Only he who has built a boat can row the first mile". Heard that somewhere; Chuck maybe. ;)

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Please read Dave Nichols fine article on scarfing after reading this story. He makes many good points on the art. I will go to beveling only one panel at a time on my next hull. I believe it will give me greater control over the process, and not have to worry about messing up sheet A if I make a mistake in the stack on sheet B, C, or D. Adding a power plane to my tool budget looks like a good thing too. :) The best advise I can give is to take some scraps and practice, practice, practice on your scarfs, and to find the way that satisfies you! The more you do, the better you will get.

I'm going to stop here with this part of the story. Many of the little details about this boat's construction, have been covered in other boat building articles by me in the links that Chuck adds to the bottom of this page. My next installment will probably concern figuring out the angles and cutting the material for the corner blocks. That has been a head banger at times.

Check out my new flickr account for this boat; it's link is http://www.flickr.com/photos/10ftnuthatch I will be adding more photos as the construction progresses, so come back often.

Thanks again for reading my stories.

Warren Messer
Red Barn Boats

On to Part2

Other Articles by Warren Messer

SAILS

EPOXY

GEAR