There are many kinds of nails, many more than is worth while to specify here, as you will probably use those of wire for most of your work. When another kind would be preferable (as is the case for some purposes) it will be specified. The nails in common use before the introduction of those of wire were known as " cut," being stamped from a sheet of metal, and " wrought," the latter kind being much older and originally forged by hand into shape, one by one (hence the name), but now commonly made by machine. The expressions three-penny, eight-penny, ten-penny, etc., indicate the length, and come from an old custom of so designating the lengths, but you need only to call for them by the length, as 2 inch or 2 3/4 inch, in order to get what you want, and you can easily select whatever degree of stoutness you need. Copper or galvanised nails and tacks will be needed for your boat-building, copper being preferable, particularly for salt water.