Scarfing and the stepped scarf

Unless you are building a boat that is less than 8' long you will need some way to connect several short plank pieces into a full length plank.

One way of doing it is with a butt block, a piece of plywood which overlaps and is glued to both parts of the plank. A butt block is not only unsightly to some people but can also create a kink or "hard spot".

A scarf joint is the method that most boatbuilders use. Traditionally cut or planed in a long bevel, it has the advantage of creating a smooth transition between the sheets of plywood, and also increasing the bonding area for greater gluing strength.

The stepped scarf that we use is cut in a series of steps that are 10 times as wide as they are tall, making a 1.2" long scarf in 4mm plywood. Not only is this joint very strong, but it has two advantages over the traditional tapered scarf:

- the edge is much sturdier than the sharp edge of the traditional scarf joint
- the steps are self-aligning making the joint easier to assemble and giving the planks a more accurate shape

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