Building the 10 ft Nuthatch - Part 2  
Design by Warren Messer - Seattle, Washington - USA

Back to Part 1

As I said at the end of the last story on building this prototype hull; I was going to talk about installing strong corner braces and how to tie the rails into them. For me, this has been an evolutionary process, as I have been changing the way that I install them from boat to boat. I can't even say that I am getting close to finalizing my approach, or even that I will stop thinking about how to do it better. My next prototype hull may use a system that is completely different, but this is the method I use now.

As a designer, I am always interested in what the old timers did with widths and depths and the placement of seats and oarlocks in the hulls. So I try to go to as many of the wooden boat shows in the Puget Sound area I can; to see whats old, whats new, what worked over time and what didn't. The Port Townsend Wooden Boat Festival is a good place to go; where I can see a lot of old and new ideas in the boats on display. The Center for Wooden Boats at the south end of Lake Union in Seattle, is another great place to go and see up close what the old timers were doing. When looking at "real" old boats, and their modern replicas, I like to take my tape measure along. That way I can gage the "size" of the various components in the boats, and compare them to the many others tied up along the docks, or sitting on the hard. I always find it interesting to see how they installed their corner blocks and rails, and the various ways they used to fit everything together.

The thicknesses of some of the components seem over sized by todays standards, and I think that had more to do with the materials they had available to them. But you can see that they spent some time fitting the rails and corners into their boats by the quality of their work. Even a plain row boat for fishing had more workmanship put into the corners and rails than a lot of new fiberglass production boats have today. A well made set of corners and rails can make a huge visual difference in the appearance of a boat, and it's not that hard to do. You will have to take some time to make it so, but the payoff in the Oh's and Ah's when people look at your boat will be well worth the extra effort you made.

The following instructions should work on any design without modifying. The main thing to remember when using this method on your hull, are the angles involved and their relationship to each other. You have the vertical angles of the side panels near the ends (should be the same), and the different vertical angles of the stern and bow panels (pram). There are also the horizontal angles between the transom/bow panels and the side panels. Hopefully this is the same on both sides if the hull was set up square in the wiring, filleting, and glass taping. I go on and on about making sure the hull is square and level in my plans, and that the height (tops) of the two side panels are the same on both sides at the stern/bow. The stern/bow panel can be off a bit from the side panels, BUT "should be higher at each end" than either of the two side panels. This can be leveled and trimmed later, but can't be corrected easily if one of the side panels is higher or lower than it's matching stern/bow panel corner. The port and starboard ends of the bow/stern panels always have to be even with or slightly higher (better) than either side panel at the corners. Always! I add an extra 1/4" to the top edges of any bow or stern panel measurements just to be safe.

Note: Make sure that the stern and bow panels are still straight from side to side. I always have a stiffener (2x2) attached at the tops of the bow and stern panels until all the fillets, glass tape, and the corners and rails are installed. The panels will take a curve if you don't!

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click to enlarge

For this hull, I modified my approach by going to a greater thickness for the corner blocks. I was able to get some true 1x6 material at EdenSaw Woods in Kent, WA, when I picked up my marine plywood for the hull. To help increase the thickness, I also added a layer of 1/4" ply to the bottom of the corner blocks after I had them shaped. Then I could install the tops of the blocks higher in relation to the side panels than I have before. I wanted to do this to help in the final shaping of the transition between the ends of the rails and the corner blocks. I succeeded in the stern, but not at the bow. It would have worked at the bow, but "I forgot" what I was doing when I installed the bow rails (not wide enough). Building boats has become automatic to me, and things happen fast if I don't remember to stop at a certain point in the construction of a new design. This was the first pram design I had used the spaced rail system on. The brain was on at the stern, but got turned off at some point when I started working on the bow.

To get the stern corner blocks ready for cutting, you need to know the vertical angle of the stern panel first. Place something close to the stern panel, that will span the distance between the stern ends of the side panels. Use an adjustable gauge to find the angle between the bottom of this "spanning board" and the inside of the stern panel. This will be used to set the "blade angle" of your table saw. I like to cut this angle in both corner blocks at the same time; and the best way to do that is to just cut one block. On this hull, I started with a 4" x 8" x 1" blank (the 1/4" plywood can already be glued in place to speed things up). That left behind enough wood for the strength I wanted, after all the cutting and shaping was done. Set the rip fence so you cut just the bevel, and not narrow the blank any more than is necessary. Mark this bevel cut as the "stern edge" on both half's of the blank .

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Next, measure the vertical angle between your "spanning board" and the inside of the side panels near the corner. Use that angle to "reset" your table saw to the new cut. It will be different from the stern angle cut. Check to see that both sides match, or are close enough for GelMagic to fix. Don't cut them yet! You still need to find the "horizontal" angle between the stern and side panels. Use your adjustable gauge to find this, and check the angle with both sides. You will have to do this on the outside of the hull because of the fillets and tape. Some error can be allowed, but this is one of the reasons you wanted to make sure the hull was level and square when you filleted and glass taped it.

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Take that horizontal angle and use it to set the "miter gage" on your table saw. That horizontal angle and the vertical angle of the table saw's blade are used together in one (hopefully only one) pass, and for only one end of the blank (port or starboard). The cut at the other end of the blank will be a mirror image of the other. You only need to reset the miter gage to the "opposite mirror angle" and not the blade. The blank will have to be "rotated" 180 degrees (not flipped) for the next pass through the saw with the new and opposite angle set in the miter gage. I like to add pencil marks to the blank as a check to see that I am actually doing things right. I have made some fancy kindling for my fire place by not thinking things through. Make a "thin" pass along the very outer edge just to check yourself that you have the correct angles in the right directions. Better yet, do a complete corner block cutting test on a piece of scrap.

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The next cuts to make are at the forward, outside ends of the blank; perpendicular to the edge that attaches/lines up with the side panel. You want to make a 90 degree cut here so the ends of the inside rails, and spacer blocks if you use them, are square where they meet the corner blocks. How "wide" a cut you need to make will be determined by how thick the combined inside rail set is. Hold up some sample stock(s) of the "true" inside rail thickness, and mark the "width" of the cut needed for the rail ends to have a full match. Do this to the forward outside corners of both blocks, and remember that they are mirror edges.

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If everything came out as planned, you have two different, but mirror image cuts at the ends of the blank. All you need to do now is to cut the blank in half and mark which is port and which is starboard. On a pram, just repeat everything again for the bow corner blocks, but remember that "all the angles will be different"! With a "V" bowed hull, laying out the angles for the breast hook is similar, but different. You still have to measure the side panel vertical angles, but the sides may have some horizontal curve in them that will not allow the use of a table saw. Tell the better half that you need a band saw for Christmas; she'll understand, right? I still have to bum a cut from a friend.

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With the corner blocks cut to the angles of all the hull panels, it's time to fit them to the hull; but first you need to round out the blocks to fit the radius of the fillets and glass tape in the corner seams. Take your time and get a reasonably good fit; really good if you are using glue; close enough if you are using GelMagic or your own home cooked thickened epoxy. For some things, I like to go out to eat.

As I said earlier; I added a layer of 1/4" plywood to the bottoms of the corner blocks. Mainly to be able to increase the mounting height of the blocks for shaping later, but also to give extra strength to resist splitting along the grain of the wood. I GelMagic them in place and trim after curing. The addition of the plywood greatly improved (reduced) the shaping of the rails in the transition to the corner blocks. It even helped at the bow corners, where I forgot what I was supposed to do to the bow rails on this hull.

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click to enlarge

Hold the corner blocks in their respective positions, and check the fit. The tops of the corner blocks are set to the height of the side panels (or 1/4" higher if adding the plywood to the bottoms) and "not the bow/stern panels". If the heights still look good, drill some holes for the stainless screws you will add for extra strength. I usually have the corner blocks loosely clamped in the "spanning board" when I drill the first hole in each corner block. Then I know that they are level with each other, and at the correct height. I like to use two screws on the ends, and two on the sides of each corner block. Just make sure you mark their locations. You will need to "miss them" when you add the stainless screws for the outer rails later. I place a pencil mark for each screw location on the outside of the hull panels, and under where the rails will go. I erase the marks later when I do the bottom, since I am completely finished with the rails and interior of the hull by then. The marks are always there and never get lost while shaping or sanding the tops, sides, and bottoms of the rails.

Put a good coating of GelMagic on the edges, and reinstall the corner blocks (one end of the hull at a time). Install and tighten up on the stainless screws, but not too tight. Just enough for some squeeze out of the GelMagic. Use the spanning board and clamps to make sure the tops of the corner blocks are even from side to side again. Remember to cover the GelMagic/epoxy oozing from the corners with plastic so the spanning board doesn't become part of the hull.

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On my earlier boats, I used a simple inside/outside rail system. Starting with the PUD-g, I have gone to what I call a "spaced rail" system. There is probably a nautical term for it, and I am sure someone will let me know. The short spacer blocks that fit tight against the corner blocks are glued in place. Their lengths are variable (to fill the distance between the last standard "open" space and the corner block) and are determined by the block and spacing lengths you are using. Attach the spacer blocks so that the tops are even with the tops of the hull panels. The inside rails will be even with the tops of all the spacer blocks when you install them.

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Next we want to inset the end of the inside rail into the corner block so it covers the joint between the last spacer rail and the corner block itself. You can go with an inset cut of either 3/4" or 1" depending on the size of the corner block blank you started with. Hold your saw next to the inside face of the spacer block and match the angle for the cut into the corner block. Do this for all the inset cuts in all the corner blocks. Installing the bow and stern inside and outside rails, and battling the fit of the inside rails along the sides of the hull is covered in my build and study plan text instructions.

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Once everything is installed and all the epoxy has cured you can do the final shaping of the rails and the transitions into and out of the corner blocks. Just take your time, and don't remove too much wood at any one place, at any one time. Go around the hull and do a section at a time, but remember to do the same thing on the opposite side. Look and shape, look and shape.

As I alluded to at the beginning of this story, things tend to change from prototype to prototype at the Red Barn. As I was futzing around with the corners and rails of the 10ft Nuthatch, I thought of another way (simpler I think) to do all this without needing to make all the fancy tablesaw cuts. I will try the idea out on my next boat, the double ended 12ft O&P Pod (Owl and Pussy Cat) with the asymmetrical pea green hull. Even though it won't have right angle corner blocks, the idea if it works will transfer to a standard transomed hull.

The 10ft Nuthatch should be in the water or close to it, around the time this story is published in Duckworks Magazine. So look for the launch story in early November. Hopefully under sail with the new 64sq ft sprit sail that I designed. Bob Pattison at Neil Pryde Sails International, finalized the shape of the leach, and the cut of the sails individual panels for me in 3D Cad. It's an in stock item for them now at http://www.neilprydesails.com/

Check out my flickr account at http://www.flickr.com/photos/10ftnuthatch
I've added a lot more photos of the construction process since the last story. With over 1800+ Duckworks Magazine and http://www.washingtonflyfishing.com/ visitors todate.

Thanks again for reading my stories.

Warren Messer
Red Barn Boats

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