The 9.5 Laura Bay - Part 5
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design by Warren D. Messer - Seattle, Washington - USA

Part 1 - Part 2 - Part 3 - Part 4 - Part 5 - Part 6

This part of building the Laura Bay will deal with the sailing rig and it‘s accessory systems. I was going to go into the construction of the NACA 0000 foil sections of the daggerboard and rudder, but have decided to do that in a separate story from start to finish. The daggerboard and rudder for the Laura Bay were completed before I had my own digital camera and much of the details that I wanted to convey could not be shown. I will show some photos of the results, so you can see that a foil shape can be accurate and easy to construct.

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For my mast parts, I made a visit to www.onlinemetals.com‘s shop in Seattle. Very helpful people and I was in and out in under 30 minutes with my mast, boom, and sprit tubes. I also watched them pack up some orders for shipment by UPS and would say that nothing should ever get damaged in transit.

Once I got the tubes home, I gave them a light sanding with 600grit and a good cleaning with a soft cloth. It took me a while to find a retail outlet that had "etching" paint for aluminum, but I found it at a local auto supply store. I don't know if the "Shucks" chain is national or not, but I would imagine that any large auto supply store near you would carry the same product. I gave the tubes two coats and let them cure overnight. I later painted them with some gray acrylic latex paint I had sitting around, but wished I had used some of the left over System Three WR-LPU, two part polyurethane paint I used to paint the hull on the 8ft Nuthatch. That stuff is tough and easy to work with and clean up. I also inserted foam into both ends of all the tubes for floatation and to limit the amount of water that could enter if submerged in a tip over. I had some high density closed cell foam left over from my first whitewater kayak that died of UV poisoning. Just place the tube on the foam and twist. It drills the correct sized hole as it goes through the foam. Just push it in a bit for the fittings on the ends of the boom and sprit to fit.

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Not much needs to be done with the mast, other than drilling some holes for the various eye fittings and snotter hook. The sprit needs to have pins in the ends of the tube for the sail and snotter line to attach to. For this I found that some 7/8” dowel (old broom handle) works with just a bit of light sanding for a snug fit inside the sprit tube. The photos and plans show how to do this. Just drill a 5/16-3/8” hole off set to one side in the dowel. You will insert a smaller dowel into this and have it protruding out at least 1” from the end. I used some 5/16” fiberglass doweling I had laying around. A hardwood dowel (birch or oak) will work fine. Assemble all the pieces into each other and drill a hole through the tubing and dowels and use a round headed #6 x ¾” stainless screw to hold it all in place. Do this to both ends of the sprit.

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The boom needs to have fittings made for both ends. One to act as a gooseneck (yoke) and one to act as an outhaul. I made the yoke out of three layers of 6mm scrap laminated together. I also cut off two small outside edges of 1 ¼” doweling I had laying around to make the part that goes into the boom tube large enough in diameter to fit tightly. Once it was all cured, I laid out the mast tube radius and shaped the horns. It was then shaped, smoothed, stained, epoxy coated, and inserted into the tube and held in place by a round headed #6 x ¾” stainless screw.

For the outhaul, I copied the shape that the Optimists use, but out of wood instead of molded plastic. I used a 2” length of 1-¼” doweling for the outhaul plug and attached the end fitting (scrap of 3/8” oak molding) with GelMagic and a #8 x 1 ½” stainless screw. The plans show the location and sizes of the holes to drill in the outhaul end piece. Everything is shaped, finished and coated with epoxy; inserted and held in place with a #6 x ¾” stainless screw. All exposed wood was later coated with varnish.

The mounting positions of all the various running/standing rigging fittings are shown in the plans.

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On this design the relationship of the CLR and CE put the mast back farther than I wanted the bow seat to extend. I was toying with the idea of a removable mast partner and having it attached higher on the hull than just being at the top of the seat. The first idea was for a flat partner that was attached to “wings” epoxied to the sides and under the inside rails. I wondered what an arched partner would look like; so I took a scrap of 6mm ply and clamped it to the rails. There was no going back to straight.

Before I could mount the mast partner, I had to locate the positions for the partner “wings” that are attached to the hull. I had the shapes cut out of ¾” material I had left over from the trim. After finishing and staining the two wings I clamped them to where the design said they were to go and to see if it looked right. The facing edges were shaped to fit the hull sides and three #6 x 1” stainless screws were drilled for and placed to hold each wing temporally for a final check. The wings were removed and the two gluing surfaces on each wing were coated with GelMagic and reattached with the stainless screws and lightly clamped. The wing to hull side angles were rechecked again, and left to cure overnight.

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I looked around the shop and found three pieces of scrap that would work and trimmed them to their finial shapes. I took an old 2x6, drilled a 5/16” hole in the middle of it and the three partner pieces and dry fitted them with a 4” carriage bolt (threads up). I covered the 2x6 with plastic, slathered up the partner pieces on their mating faces and assembled them in the mold. I put scraps of 3 ½” hardwood t&g flooring under the ends(under the plastic), and moved them in until I had the end to end cord length I needed to span the gap between the rails where the “partner wings” would be attached to the hull sides. I then let the partner assembly cure over night. The next day I trimmed the ends and rounded the edges.

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To make the opening for the mast, I had to make sure that the original 5/16” hole was close to the centerline of the boat. Back out come the strings and pencil bobs, and making sure the boat is level side to side and close to what I thought (wished) the fore and aft trim should be. Once I had the boat level and trim, I could then mark the center of the opening for the mast in the partner. I also had to make sure the ends of the partner were equal fore and aft, marked, clamped and drilled into the partner wings. The mast opening was marked, cut (oblong the opening fore and aft a bit, to counter the slight angle from horizontal of the partner, and let the mast fit and rotate), and the edges rounded over. I later added a "keyhole" cutout to the port side of the opening to allow an eye for a vang attachment and a anti-mast losing pin to pass through. Both are offset from each other, so you have to rotate the mast a little between each part going through the mast hole. It can't come out on it's own now or lift off the mast step when running.

Once the mast hole was cut, I had to locate the mast step position in the hull. I dropped a longer stringed pencil bob through the hole and marked the location on the hull. My mast step was going to use a 2” PVC “plug”(the kind that fits inside the pipe) to hold the bottom of the mast. The plug has a 2” ID and was a perfect (cheap) fit. To mount the plug, I needed something to fill in and level out the “V” in the keel, and make it perpendicular to the mast. I used my old gap filling standby EZ-Fillet, a 1” section from a 3” diameter plastic bottle, and a plywood circle cut to fit inside the plastic ring. Slide the plywood into the plastic ring, set them on the bottom of the boat, and hold a marking pen next to the hull as you mark a line around the plastic ring; then cut along the line with scissors. Press the plywood circle to the upper (level) edge and check the fit, and trim the lower edge as needed so the surface remains perpendicular to the mast. This is important, as its a close fit between the mast and the inside of the PVC plug. Any mismatch and the mast binds inside the plug. It can be shimmed later with stainless washers if it's off.

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I had a 4 foot length of thin wall 2” OD electrical conduit that I used as my mast tester. I placed the plastic ring in position, set the PVC plug on top, and inserted the mast into the plug. I then checked for level and true again. Once I was happy with the fit, I mixed up some EZ-Fillet; then filled and shaped it to the contours of the plastic ring and let cure overnight. The rings were then attached to the hull with a layer of GelMagic, positioned, and left to cure overnight. The PVC plug is then drilled through it's center and screwed to the center of the mast step attachment point after sanding and coating the plywood ring with a layer of epoxy.

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The daggerboard and rudder are designed to be NACA 0000 foils from the Naca4gen program. I take the information the program spits out and enter it in my drawing program. The daggerboard is a NACA 0010 and the rudder is a NACA 0012. The 0010 gives the ratio of the thickness cord to the distance back from the leading edge of the daggerboard. I used a width of 10" (not a part of the 0010)and the thickness cord came to be around 1" at 30% from the leading edge. The rudder I set to 8" wide and the cord width came out at 1" also, but the upper part where the pintles go is only ¾" thick. I'm able with the software I use to draw this out with an end view; and then figure out how to stack 1/8" (3mm) plywood of various widths and lengths, to get the outline of the foil shape. Then it's cut out the pieces, coat with epoxy, stack, and let cure. I then mix up the EZ-Fillet and fair in between the stairstepped edges of the plywood stack. Then its sanded down and final faired with epoxy thinned Quickfair; then finish sanded and coated with Silver Tip epoxy, and sanded fair again. I then roll on three to four coats of either System Three's two part WR-LPU, or their Marine Enamel to finish it off. The construction of the rudder and daggerboard is more involved than this and will be expaned in greater detail in a later story.

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Now its time to mount the rudder and it's hardware. You need to know where the centerline of the boat is on the stern panel, and to establish those reference points. I place pieces of the "green or blue" masking tape where I think the centerline is, and mark the true position on the bits of tape with a pencil. On this boat you need to shorten the pins on the pintles so you can mount the upper gudgeon high enough on the stern panel for strength and still let the top of the upper pintle clear the outer aft stern rail. So I place the shortened( pin) upper pintle in a gudgeon and determine it's mounting position, and still have the head of the pintle clear the rail when lifted out. Mark one of the holes and drill it. Use one of the machine screws and nuts to hold the gudgeon in place while you aline, mark, and drill the second hole. Use another machine screw and nut to keep everything lined up as you drill the last two holes. Measure down from the upper gudgeon, the distance listed in the plans and mark with a bit of tape. Line up the lower gudgeon on the stern's centerline and mark the first hole.

One of the things you can do to make this go easier, is to take a piece of 3/8" doweling (this boat uses the medium pintle and gudgeon kit from Duckworks BBS) at least 1 foot long, and use it to act like a long pin and hold the gudgeons in line on the centerline of the stern panel. That way the upper and lower gudgeon pin holes are forced to be in a straight line if the dowel is straight too.

Repeat the drilling and bolting sequence you used earlier to mount the lower gudgeon. Don't tighten the machine screws and nuts down yet, just snug.

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Set the rudder height so the top of the foil section is just below the bottom of the hull at the stern. Insert the pintles into the gudgeons (short pin on top) and bring the rudder into the tangs of the pintles. I use a couple of clamps to hold the rudder in place while I fiddle with the fit. I also use the 3/8" dowel again to determine how far the rudder is inserted into the pintle tangs. Just another way to keep everything lined up. Once the rudder is at the right height, and tight against the dowel in the tangs, I clamp it down tight and check the swing from side to side. If everything is ok, I drill the forward holes in the tangs first and insert a #10 round headed machine screw into each, and tighten with a Nyloc nut. Check the side to side swing again, and if all is still good, drill and mount the second set of machine screws and nuts. If this was a perfect world, it should swing with no squeaks or grinds, but it isn't, so you have to just say (if it's not too bound up) that it can wear in. If you used the dowel trick, everything should be ok or at least close enough for Red Green. ;)

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Now take off all the hardware from the hull and rudder and get them ready for their final finishing. Take a countersink bit and cut a slight bevel into the outside holes of the stern panel for the lower gudgeon's machine screw holes. These will be filled with sealant to keep out any water that tries to get in. Its also a good idea to give the inside of the holes a light soaking with epoxy.

Once the hull and rudder are painted and cured, the pintles and gudgeons can be installed. Re-insert the machine screws (I put the heads on the inside) and put a good bead of calking sealant around them filling up the countersink bevels (plus some extra) you made on the outside of the hull. Replace the gudgeons and tighten all the machine screws and nuts. Scrape off the excess sealant that squeezes out. Mount the rudder again and pray that it still swings free. A little polishing with some emory cloth on the pins, and some honing with a small rat tail file can free up a sticky rudder.

This will conclude the series of stories on the construction of the 9.5 Laura Bay, but I will have a follow up article and photos of rigging the sail and the sea trials. Look for the plans to be on sale soon as I double check all my drawings for the final changes that I have made.

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Thank you again for reading my stories and the comments you post.

Warren Messer

Red Barn Boats