What is "spiling"

vb. (present participle of spile English)

Spiling is a traditional technique used in temperate regions of the world for the prevention of erosion to river and stream banks.

Willow spiling is currently used in the United Kingdom; live willow rods are woven between live willow uprights and the area behind is filled with soil for the willow to root into.

Kipling's poem The Land mentions it: "They spiled along the water-course with trunks of willow-trees, And planks of elms behind 'em and immortal oaken knees."

The species of willow used are riparian (associated with rivers); the posts, in diameter, are usually Salix alba or S. fragilis, and S. viminalis varieties are used for the interwoven rods. The living willow posts are driven in to the bank, to a depth of or more, at intervals and the thinner rods are woven in between, the rods are best woven at an angle slightly above horizontal to ensure good survival rates. A row of stones, gabions or wooden planks held by posts can be added to the bottom of each "spile" to prevent undercutting when the willow is establishing itself. All works should be done during the dormant period, winter in temperate zones. A layer of seeded coir matting can be pegged onto the soil on top of the spiles to prevent the soil being washed out during flood events. This method is an example of soft engineering, techniques which tend to be less expensive and more sustainable than others.

Spiling is a technique used in building wooden boats in which a smaller component is used as a pattern against which the outline of a larger component can be drawn. This is often used for creating planks on traditionally built boats that have complex shapes..

When used for making a new plank for a boat a piece of timber the same length as the desired plank but both thinner and narrower is cut. This is called the spiling batten. This is then temporarily attached to the boat in the place of the plank required. The shape of the plank required can then be traced onto the spiling batten using a compass, or a dummy stick. The spiling batten can then be lifted out and placed on the new stock, and moved around to find the optimum use of the stock material, the using the same compass or dummy stick, the exact shape required can be traced off the spiling batten onto the new stock, ready to be cut out.

When spiling a complex curved shape it is important to keep the dummy stick in the same orientation, and not allow it to follow the curve, otherwise a distortion of the shape will result. The shapes of boats planks are complex as the plank gets wider to cover the broader midships and then narrower as the planks converge towards the bow and the stern.