Jump to content




Whaleback moulding. Pattern on left, vacuum moulding on right


Whaleback moulding. Pattern on left, vacuum moulding on right

This is the moulding tool (pattern) made from an offcut of roofing joist timber for my Alexanders model. A paper template is made by pressing it down on the finished gunwale rails and making a template.  Using a belt/rotary sander, the shape of the tool is matched to the rail shape. The vertical profile of the gunwales is measured  from the stem and going back in increments to the full extent of the whaleback. The measurement is taken from the horizontal and marked on the sides of the pattern.  When the lines are joined up, they will indicate the position of the top rail relative to the top of the whaleback. Fix a piece of scrap wood below this line which will give a cutting line for the finished mould. It is important that at least one hole is drilled in the top of the whaleback and several on the gunwale line for the suction to form the crisp finished shape of the required moulding. A crisp bend guides the knife when cutting. ALWAYS CUT AWAY FROM YOU AND YOUR BODY PARTS. Any plastics vacuum-forming company will be happy to do a mould or two from the moulding tool using 2mm thick styrene.  I always ask for two moulds in case I make a hash of the first when cutting. Believe me if you hash one up, you won't hash the second. Always remember to allow 2% for plastic shrinkage when making the pattern.