I am hoping someone can tell me the name of (and remind me how to use) a boat building tool.

It is used to get both sides equal. That is, matches the curve of starboard and port so that both are exactly the same. It is usually used for decking.

It is a very simple tool, which might explain why I cannot for the life of me remember what it is called or how to use it. Basically, it is any old piece of timber with some V shaped wedges cut out at one end. Then, some how, it is used to measure the curve of one side. Then those measurements are used to mirror for the other side, giving an exact match.

Thanks in advance :)

EDIT: How did this get into Introduce Yourself ?