fastenings what surveyors ought to know about
If all else fails, use ******* great nails Traditional shipwright’s working rule - Orchard Dock, East London.
BY EUR. ING. JEFFREY N. CASCIANI-WOOD Hon FIIMS
Wire Nails
Ordinary steel wire nails are never used in the boat’s structure as they rust very quickly but they may be found in the interior joinery work or under the sole through the bearers. Although steel nails are the most commonly used, nails are also made of aluminium, stainless steel, copper, brass, bronze and plastic. Aluminium, copper, brass, bronze, stainless steel and plastic nails are rust proof but bright steel nails will rust so they should not be used where rusting would cause discoloration or staining. The thickness of the materials to be nailed determine the length of the nail required but the amount of stress or weight the materials will bear should also be considered. Nails are typically sold by length in Britain but in America by their so- called penny weight size indicated by the symbol d and, in a throwback to Colonial days, meant the number of pennies they cost per hundred nails. Many head styles are available and each offers advantages for certain applications. The flat head is a general purpose head that is the most popular and the most economical. A flat countersunk head leaves a smooth surface as it levels out with the top of the surface driven into. Nails come
in many point types. Each point has certain advantages for certain applications but the diamond point is a general purpose point for wood use. It is the most common, least expensive and is easy to start. Oval nails are oval in section – see Figure 12 and 16. Selection of the correct nail head depends upon the hardness of the wood, the chance of the head working through and the type of work to be done. A finishing nail, for example, must have good holding power yet be inconspicuous. The various common types of nail that the marine surveyor may come across are discussed (in alphabetical order):
1. The Annular or Ring Nail Figure 5 The Annular or Ring Nail
This type of nail which hole is sometimes called a gripfast nail found is found in various forms and in all of them the shank has a unique either annular or screw thread. When the nail is driven, the grooves on the shank turn the wood fibres into small wedges which grip the shank tightly and add to the withdrawal resistance. The teeth of the nail hold it in place firmly and such nails are often used for fixing plywood and similar materials. The annular and spiral threaded nails can be distinguished from a knurled nail by the smooth shank between the head and the beginning of the thread. Annular threaded nails (sometimes called ring shank nails) offer the maximum holding power in a number of specific applications. They are best used with softwoods and plywood but have many other applications.
42 | The Report • September 2020 • Issue 93
When driven, the threads like those of the gripfast type separate the wood fibres, which then lock into the rings, thus resisting removal. Spiral threaded nails (called screw or drive nails) turn when they are driven, much like wood screws and actually form a thread in the wood fibres. They offer good holding power. Spiral threaded nails are specifically designed for use with hardwoods and dense materials. Ring shank nails, sometimes called deformed shank nails, are nails with ridges or grooves along the shank and are similar to screws in that they have a specially designed head which allows them to be hammered below the timber’s surface. They have a much better holding power than nails with a smooth shank because the rings act as wedges to keep the nail firmly in place. The pattern of ridges along the shank of the nail can vary depending on the manufacturer and the intended use of the nail. Some brands have very shallow rings that provide a small amount of extra grip, while others have much larger ridges. Some have spiralling grooves, while others have a neat set of ridged rings. This type of nail is better suited for the harder timbers and areas where more securing strength is required. All of the above nail types need suitably sized pilot holes as they are hard to drive.
2. The Clout Nail and Tack Figure 6 The Clout Nail
The clout nail is a short usually galvanized round headed wire nail used to fasten fabric to a wooden structure such as felt to a wooden
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