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I'm going to try to document a new build I've started. It's an enlarged Mellon Seed.



This is one recently sold and it's a "Cortex" version, which is what this build will be patterned after. There have been several "versions" of the Mellon Seed which can be seen in the book American Small Sailing Craft (Chapelle), most are enlarged a bit, some as much as 21'. They're low and lean gaff cats, most strip planked, but a few are lapstrake, as will this one be.



The first part of the job is to make a strongback. My strongbacks are usually over built for lapstrake builds, because you sometimes really have to torque the planks into place, which can twist or distort a flimsy strongback. Note the one picture shows a neat way to level the legs of the strongback. The frame pieces were built on a table and the legs added after, but the floor isn't perfect, so a few well placed screws will lift legs as they need to be. This one needed nearly a 1/4" to level out the back of the strongback.

The inner stem is oak and needed to be 1 3/8" thick and over 24" long. This is a big hunk of wood to cut, but more importantly epoxy. I would have had to use a 2x12x24" hunk to carve this piece, so I elected to bust it up into smaller pieces. This will permit the oak to be stabilized by epoxy (1 3/8" solid is just way too big), without internal stresses tearing open the coating later. I used 1x4, milled to a fat 5/8", then band sawed to shape. I staggered the break in the stem, so when it's glued up, it'll have enough overlap to hold together. The other photo shows the 4 pieces disassembled.

Except for the transom mold, the stations are placed. Two days work and I've just finished plumbing and leveling the assembly. Only one mistake, I placed station twelve 1" too low (if you look closely, station 12's height off the strongback is marked on the mold). This is a common error, seen in carpentry. You use a ruler or tape measure, but are looking at it upside down, so you mark on the wrong side of the number you're after. In this case I need to be 6 1/8" off the strong back, but because I used a ruler in this case, upside down I marked the height at 5 1/8". Oops . . .  I just laid a batten on the centerline and it looks like it's supposed to. This is the most important part of the build, having a dead nuts square strongback, with station molds erected plumb and level to it. Next it's getting the stem aligned with the centerline and positioned stiffly enough to accept the strains of line off battens and eventually the planking being bent around.

I've also decided to pin the stem pieces, so alignment will be easy, once the goo is applied. To give you an idea of "scale" the stem pin picture has a drawing of the strongback under it. This is an 11"x17" piece of paper. I've yet to drive the dowels, which I'll do when I epoxy the parts together. Epoxy can be slippery stuff, so this is an easy way to insure alignment is dead on, come goo time.

Sweet shape to that boat.  The bottom looks like she'll plane fairly easily.  I like your strong back leveling technique.  Do you foresee any issues when you're wrenching planks on with the screws digging in/bending? 
Looking forward to more pics!

She's lightly planked, though there can be some torque issues, so if necessary, I'll toss some concrete blocks on the strongback to hold her down. If I was really anal about it, I'd "Tapcon" the thing down to the floor.

I had to make up some new battens, so I haven't any new pictures yet, but will post some soon. I didn't want to use my 24' battens on such a short boat, so I needed a new set of 16', so I ripped up 10 of them. They'll back up the laps under the planks, so they lay fair during the process. This is only necessary on 1/4" planking with 24" station mold spacing. The thin planks will sag a touch in the flatter after sections, so a batten holds the shape, until the goo cures. The battens will be covered and don't remain in the boat. The only thing that will remain with the boat at roll over will be the inwale (like a shear clamp, but on the planking).

I have got the transom mold mounted and the stem is goo'd up, ready to install. I spent a half a day getting her plumb and level, then I threw some battens over her and she looks fair. Transom rake is 45 degrees, so she's a pretty thing. As to being able to plane, well she should, but she'll need some wind, say in the 12 knots range, before she can "get up". She'll be light, less then 200 pounds (I'm shooting for 180), which is considerably less that others of her type. Against similar versions, she'll kill them in light air, but things will equal up in modest air and she'll need to be reefed sooner in heavier.

The stem is glued up and mocked up in position, so I can rig big braces. A lapstrake build places huge stains on the stem until it's assembled, so it needs hefty bracing or it'll tweak off in one direction.

After I built a transom mold, I tossed a batten over the centerline to see the revised keel profile. The original had a hook in the aft section and a dead straight keel line from midship forward. I removed the hook and added a touch of rocker forward. These two minor changes will make her more maneuverable and offer much better performance potential.

The preliminary line off . . . It needs adjustments, as you can see, but it's fairly close.

I will line off only one side, knowing the other is the same. I'll then scarf two sheets end to end for each set of planks. Next I'll place the joined sheets over each other and cut both sides at the same time. I haven't decided if I'll spring a batten and use a laminate trimmer and spiral cut bit or just a jig saw, but in either case I'll cut over a piece of cheap 1" foam sheet, so the bit or blade can punch through, cutting both layers of plywood, yet not hit the table it's on. If you place the plywood good face to good face, it'll be a clean exterior cut when separated. I'm using BS-1088 material so both sides are an "A" quality, but a neat trick if working with material that has a bad side.

Yes, that's multiple empty trailers out in the yard, welcome to my place. Come on guys, it's still winter for most of you, get out there and build something, so you have something to putter around with come warm weather . . .

I haven't put a lot of time in the Mellon Seed, but have gotten a few things done.

The first picture shows the garboards being rough fitted. I made a cardboard template, a simple tracing of the battens. Then I cut the stock a little over size (just in case) and fitted them where I thought they needed to live. Next using a laminate trimmer (a RotoZip in this case) and a flush cutting bit I followed the battens. You can see in the next picture that it's pretty reassuring the template tracing, transferred to the planking stock is also where the router bit happened to cut (always a good thing.

This is the beauty of this technique. You just rough out the plank patterns and clean them up with the router. Of course as you can see, the station molds get in the way as the router bit bearing hits them, but these are easy to clean up with a multi tool. It's almost fool proof, assuming the batten line off was clean, neat and sweet.

What you can barely see is the bottom plank, which is laying on edge up against the legs of the strong back. It's centerboard slot is cut and a hunk of 2x4 is screwed to the scarf to hold it's position. It had to be removed to get the garboards routed. All the planking will be done this way. The bottom plank lives under the garboards, then the garboards are sanded flush with the bottom plank. This is followed by another bottom plank, called the keel plank (a little thicker) and it's edges are rounded over. Then the whole shooting match, bottom plank, garboards and keel plank are skinned in 8 ounce cloth, sealing them up for good. This is the only portion of the exterior that gets 'glassed.

Looking great Paul , very well written build!

Will

To continue, the planking progressed, eventually getting to some primer, of course after the seams are glued and smoothed up.

The sheer strake was to be varnished, so is missing initially, as the planking gets smoothed and painted. Eventually, the hull finish and sheer strake are installed.

Once rolled over, she gets her innards.