Chester Yawl build log

Builder's Forum
1

  Rather than hijack someone else's thread I will be posting my problems, solutions and struggles in this thread. 

 So far my biggest screw-up was glueing up the planks incorrectly. I was so worried about getting the measurements correct, that I did not notice that I had bonded the left bow plank to the right stern plank and vice versa. This meant that the bevels were on opposite sides of the plank front to rear. Oh well, the wait while the new parts are CNC'd and shipped let me build the seats and footbraces and stain the bright finished parts.  

   One thing I found is that the bevels that need to be cut into the planks are slightly curved following the shape,of the plank edge. If you clamp the left plank ontop of the right to use as a guide for your plane, the bevel will be a perfect match for the plank. When one side is done, just swap the planks and use the other as a guide.

   When mixing MAS epoxy, in my case 1 tablespoon of Cab-o-Sil per pump of resin gave a perfect mayonnaise thickness, the same with the wood flour: 1TBS per pump of resin gave a nice peanut butter consistency. YMMV, though....

 

  I am spraying my primer and intend to try spraying all of the finishes including the varnish. I have a cheapo Harbor Freight HVLP touch-up gun with a 5.5 oz capacity that works well  for this. It seems that 4 tbs of primer with 1 to 2 tbs of thinner gives a nice balance between easy spraying and rapid build. I am building up thinner smooth layers of primer over a couple of hours and then letting it dry 24 hrs, this lets it sand without clogging.

 

  If you intend to stain any of the wood parts, I suggest you do so before you epoxy any of the parts. Epoxy on the wood will prevent it from taking up,the stain and will leave it looking blotchy. Also once you,have the stain applied, DO NOT let any alcohol ever touch it again, like when you smooth epoxy filets, it will remove some stain and again, it will be blotchy and uneven. I found that the best way to get an even color was to dilute the stain 5 to 1 with alcohol and then apply very generously with a rag. It is much easier to be consistent when applying multiple light coats than one heavy one. Try to keep the stained parts out of the sunlight: even a couple of minutes of direct sun will cause fading. Shadows on the wood will result in darker areas and the sun will give lighter ones. 

 

  I found my router to be very useful for rounding over any edges before assembly. A 1/4" and 1/2" rounding over bit was all I needed to break the edges for a nice look and feel. 

 

   For a building table I split a 4x8 sheet of OSB lengthwise and attached some 1.5" pine boards to the underside with glue and drywall screws. This stiffened the table and I used the boards to connect the OSB together end to end. This gave a 16'x2 table which I covered with plastic to prevent the epoxy from sticking. With the table on a pair of leveled sawhorses and with a third sawhorse in the middle I have a solid workplace. Just set a couple of upside down 5gal buckets on top and and lay your wired together #1 planks on top,of them and you can start wiring in the sides..

2

No need to replace planks epoxied incorrectly.  Just buy a cheap heat gun at Harbor Freight and run it back and forth over the scarf. It will eventually soften and separate.  Had to do this with one of my Yawl scarf joints and was pleased with how easy it was to solve the problem

 

RichMPL

3

  I think it might be dependent upon how long the planks have been bonded. I called CLC on the Monday after I discovered my error, but it had been 5 days since I clamped them up and the guy on the phone thought it was too long to try that. How long was it for you? 

  In a way this may give a clue to the answer to my next question: Can I epoxy coat some of the parts before I install them? I am thinking of the frames, the transom and the fore and aft seat panels, I have an even coat of stain on them and I would like to stabilize them and prevent anything messing that up. In other words, will a filet bond to a cured epoxy coated part as well as it bonds to bare plywood? All my aerospace composite experience andntraining tells me it will and I see that other stitch and glue boat kits (PT Skiff) pre coat parts before installation. For that matter, so does CLC, if I am seeing the construction photos of the Wherry Tandem correctly. And it sounds like CLC is OK with reglueing the scarf joints on separated planks too. Anyone have any input? It's Saturday morning here, so I can't call until Monday......

4

  I did some more research, including Lazlo's schooner project and it sure looks like there are not any issues with percolating the frames and other parts with epoxy prior to assembly. So I have decided to start coating all the stained wood to stabilize the color and so that I can do as much of the finish work with the parts flat on the bench. There are a few hollows and dents in the surface that I will try to fill this afternoon with epoxy and micro balloons I have left over from a car project. I hope that it will be easier to sand than the wood flour mixture, but I'll find that out tomorrow once it cures....

  The Interlux primer was a little easier to sand after an additional 24 hrs drying, this time inside the warm house instead of out in the shop. It still loads up a lot more that I would like though. 

5

Don't remember exact cure time, but it was at least a week.  Give it a try with the heat gun. If it doesn't work, the heat gun comes in real handy for later parts of the build(removing excess epoxy, etc.)

 I epoxied all parts except the planks. To be sure of a good bond, I left parts that would go together bare.  E.G. edges of frames and bulkheads)

 

RichMPL

6

  I went out and knocked the nubs off of the first coat of epoxy with 150 in my electric jitterbug. All went well and it was easy to clean up the bevels along the edges and at the nose with a wood block wrapped in sandpaper. I did notice that the roller had left a lot of bubbles on the surface for me to sand smooth the next day and it ocurred to me that this is why rolled finishes get "tipped" with a dry brush. So after I rolled some epoxy on to more parts today, I went over it with a dry foam brush as if it was varnish or top coat et voila: no more bubbles and a smooth surface! I am doing all this under a carport so a bit of dust is inevitable, but this was a big improvement. All of the parts have their first coat of epoxy and will soon have the second one. It was really easy to sand the planks between coats while they were flat on the bench and the same all the other parts too.

  I already have replacement planks coming out to me along with a few parts that were missing or got damaged in transit so I probably won't try to separate the planks, but I will keep the whole "heat it up" trick in mind if I screw-up like that again.

7

  I worked on the floors this morning, sanding off the nibs from the first coat of epoxy and fitting the stiffeners to the undersides of the floor. I had to file the tabs on the stiffeners to get a perfect fit, but it only took a couple of minutes. Then I wiped everything I had sanded with alcohol and a clean rag in preparation for the filets. 

  To help keep the stiffeners in place and perpendicular to the floors I squared them up and used super glue to hold them in place while filleting. This worked great! A couple of tiny filets of isocyanate and a spray of accelerator and everything was frozen in place for filleting. What a great tip from CLC! BTW, I used the thickest of my various iso-glues and it worked great with no drips or runs. 

8

  The shipment from CLC with my replacement planks arrived this week and I have been spending my time glueing scarfs and coating the finished planks.

  I am coating both side of the planks at the same time, just flipping the wet side down onto the visqueen covered work table when rolling the other side. Then I set them on edge to cure. I made a couple of rake-like devices from scrap wood and long drywall screws that I fastened to hang over the edge of the table. They serve as a sort of comb to hold the planks upright and still keep them apart, by hanging it over the edge of the table I can let the curve of the planks hang below the surface of the table. Packing tape on the scrap wood keeps the wet epoxy from sticking and a pair of screws about 1" apart keep the planks upright. It also makes it easy to roll the edges of the planks.

  The cured planks were very smooth and even despite having one of the wet sides pressed against the table while I rolled the other, it seemed to flow out and smooth while it was curing in the vertical rack. I did try to coat the inside of the planks first so that the (more important to me) outside of the plank was the last side to be rolled. I also "tipped" the rolled epoxy with a wide foam brush to break the air bubbles, this left a very smooth surface for the second coat. 

  We had our first rainy day in months this week and I discovered one benefit to epoxy coating the parts before assembly: after coating the plywood planks are waterproof! Even with a single coat, the raindrops just beaded up.... My building area is outside between my shop and our house and is nearly 30' long, unfortunately my roof is only 14' long and the ends of the planks stick out the ends. It is not usually a problem in summer, but winter is the rainy season. 

9

What a fun couple of days! I got all the new planks glued and coated followed by curing and a quick sanding to clean off the nibs and it was time to stitch 'ER up!

   I wound up doing it upside down on my long bench. The #1 planks I stitched together like a book and then opened then up and laid them flat, inside facing down. The #2 and #3 planks just stitched right up, but the #4 and #5 planks were a lot harder to bring together to stitch. I wound up resting the assemblage on a couple of 5 gal buckets with a tub of wood flour from CLC on top, this was just the right height and width to let the planks hang down on either side and allow them to move towards their final shape as I stitched along. Eventually, I had to add a second and third bucket to each stack under the planks. At this point it was still just a floppy collection of parts, not a boat yet!

  I was able to get all 6 planks stitched together by dusk and as the light was fading, I clamped the bow together and slipped the forward frame into place to spread the planks. Suddenly it transformed from a bunch of wood into a BOAT !! Wow, what a payoff for a great day..... 

  The next day, I flipped the (now!) hull and stitched up the bow using lots of spring and quick-clamps to align the planks and hold them in place. This went very easily and only took a few minutes, then it was on to the transom. As the instructions recommended I hung the transom from the #6 planks and drilled and wired the top holes, left and right, and then drilled and wired the point of the transom to the #1 planks. I kept breaking wires, so I switched to some 16ga wire which is much stronger and was able to get it all wired into place with little more difficulty. The 16 ga wire fits into the same hole as the 18 ga supplied by CLC so it is easy to substitute it when and where it is needed for that extra pulling force.

  I finished up for today by temporarily clamping all the frames into place as well as the breast hook to allow the hull to "get used to" it's new shape. It will rest that way over Thanksgiving until I am back on the job Friday. Boy, she sure looks good......... Now it's time to open a cold one and spend some time just lookin'.

10

Been a while since my last update: took some time off for the holidays, but have been progressing along. I made good speed until I glued the seams with epoxy and cab-o-sil, after that it took forever to square the seams at the laps to get a crisp shadow line. The manual did not really go into much detail at this point so the seams got a bit over filled. It took hours of work to remove all the excess and restore the angles of the laps. But at last it is done. 

  Today I filled the wire holes with wood flour taking care to remove all the excess before it cured. That's a lot easier that removing it with sand paper later! Tomorrow I will sand the bottom smooth and put a couple of coats of unthickened epoxy on it. Then I'll flip it over and start on the interior. 

I thought the structure had stiffened up a lot when I installed the frames and tightened up all the wires, but that was nothing like the way it feels with the hull glued up. What an amazing design.....