How to Layout an Elliptical Taper for Spars

Building a wooden sailboat mast, boom, or yard? Here’s how to lay out a proper elliptical spar taper — the traditional shape used on real wooden boats.

In this video, Mark from Nomad Boat Building walks you step-by-step through the simple layout method used to create an elliptical taper on wooden spars. Whether your boat plans give you full dimensions or just major and minor diameters, this technique lets you accurately draw and cut a fair, traditional taper using basic tools and a scrap of wood.

This is an essential skill for wooden boat builders working on masts, booms, and yards — and it’s much easier than it sounds.

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⏱ Chapters:
00:00 Who This Video Is For
00:12 What Is a Spar Taper?
00:27 Why Spars Have Elliptical Tapers
00:33 What Boat Plans May (or May Not) Include
01:23 When You Have to Figure It Out Yourself
01:49 Tools Needed for Layout
02:09 Establishing Reference Lines
02:42 Major vs Minor Diameter
03:02 The Concept of Stretching a Circle
03:21 Dividing the Circle into Equal Parts
04:20 Transferring Measurements to the Spar
05:26 Connecting the Dots for the Elliptical Curve
06:16 Using a Batten to Fair the Line
06:35 Important: One Face of a Spar Is Often Straight
07:27 Real Example from Boat Plans
07:52 Rounding the Spar (Teaser for 7-10-7 Rule)

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