Thread: Scarfing WRC

Technically, scarfed strips for planking are the same as continuous lengths of solid lumber. In fact, depending on the type of strip plank build (there's about a half a dozen distinctly different stripper methods) you can skip scarfing the strips all together. This isn't rue of all the strip methods, but is true for most of them. If you tell me the planking "schedule", I can tell you if you need to scarf or not. The schedule is the completed planking, as if you took a hole saw and removed a 3" diameter piece for inspection, what would it reveal, sheathing type and thickness, wood type and thickness, strip size, etc.

Its for the Glen L Amigo.
Amigo trailerable cruising sailboat

The frame construction details are:
Amigo Notes

I like the strip plank on wood frame method, gives a sense of security (and 2 methods of attaching planking).

So, single layer of 25 mm WRC followed by Quadaxial glass (probably overkill) on the outside and Bouble bias on the inside.

I'm not sure of the thickness of Amigo's internal sheathing, but I'm fairly sure the outside is thick enough to go scarfless on the strips. Scarfs aren't difficult on the strips and a simple jig can be made to cut them in less then a minute by hand.

You can have short lengths of planking strips.

And butt joint them on the frame or backing block?

If the inner sheathing is 18 ounces or more, then just butt them. They don't have to be on a butt block or frame. Edge nail them to the previous strip, butt up to the next one and keep on going. Once the sheathings go on, it doesn't matter. Epoxy is that strong.

Thats great, so all I have to do with the short pieces is to ensure I stagger the joints. That gives me several choices available for glass. Just out of curiosity, why 18 ounces; is that minimum weight to strength ratio or does it have to do with shearing forces?

I'm assuming the outside has at least 24 ounces, so with 18 or more of biax on the inside, the elasticity of the wood, which is acting more like a core then a single planking element is matched by the fabrics. If you're going to use really short pieces then use a small miter cut to increase gluing surface area at the end grain. 2:1 should be fine. On pieces that are longer, say 2 meters or better, then a butt joint will do. Technically, you don't have to stagger the joints either, but honestly I can't do this and space my joints as widely as I can, to be on the safe side. Again if you want to scarf with say 6:1 or 8:1, you can make a very simple ramped jig and use a hand plane on the strips. I can do a scarf bevel in about 15 seconds this way. I usually scarf all planks on one end, then set up the jig on a saw horse near the boat. Slap a strip in the jig, clamp it, 6 or 7 swipes with the plane and it's ready to hang. I have a buddy that uses a Japanese saw and a custom made miter box to fit the strips. He'll insert a strip, a few pulls with the saw and he's done.