A Simple Spar Repair with West System Epoxy

Learn how to extend a wooden spar using a proper 20:1 scarf joint and West System 105/205 epoxy. In this step-by-step boatbuilding and woodworking tutorial, Mark from Nomad Boatbuilding shows how to laminate, prep, clamp, and glue a long structural scarf for a mast, yard, or boom extension. Perfect for wooden boat repair, spar restoration, or anyone wanting cleaner, stronger epoxy joints. Get West System products here: https://www.westsystem.com/ My website: https://www.nomadboatbuilding.com Here are some ways you can support this channel. Buy some merch: https://www.nomadboatbuilding.com/shop/ Support these videos with monthly or annual pledges at Patreon: https://www.patreon.com/nomadboatbuilding Or make a one time donation: https://www.paypal.com/paypalme/nomadboatbuilding 00:00 – Intro & Project Overview Mark introduces the spar extension project and explains why this small job offers a valuable woodworking lesson. 00:37 – Why This Spar Needs Extending Discussion of the customer’s boat, new sails, and the need for a longer yard. 01:07 – Scarf Ratios Explained (12:1 vs 20:1 for Spars) Why spars need a longer 20:1 scarf for strength. 01:54 – Examining the Original Spar Construction Laminations, voids, and why a solid extension piece is acceptable. 02:33 – Choosing and Preparing Stock for the Extension Selecting Douglas fir, adjusting thickness, and prepping veneer strips. 03:40 – Cutting a 12:1 Scarf on the Veneer Strips Scarfing veneers to increase thickness as needed. 04:20 – Surface Prep Before Epoxy Sanding, marking orientation, and preparing pieces for glue-up. 05:02 – Mixing West System 105/205 Epoxy How much epoxy is needed and Mark’s “1 pump per square foot” method. 06:25 – Proper Epoxy Mixing Technique Mixing times, pump priming, and avoiding bad ratios. 07:30 – Wetting Out Porous Douglas Fir Why you pre-coat both surfaces and allow time for absorption. 08:55 – Letting Epoxy Soak & Preventing Glue Starvation Managing resin absorption in tight-grained Douglas fir. 09:45 – Veneer Glue-Up & Clamping Strategy Using the bench as a caul, managing squeeze-out, and clamp spacing. 11:40 – Tips for Controlling Slippery Epoxy Laminations Clamp pressure, avoiding shifts, and selecting proper clamps. 12:40 – Cleaning Up Epoxy Squeeze-Out Table saw trick using a temporary fence to remove cured excess. 13:28 – Building a 20:1 Scarfing Sled Constructing a simple, accurate sled for long tapers on a tablesaw. 15:42 – Dialing in Scarf Accuracy Shimming, recutting, and using sharp blades for clean results. 16:55 – Cutting the 20:1 Scarf on the Extension Piece Using the sled for a consistent feather edge. 17:40 – Preparing for Final Spar Glue-Up Aligning the new stock, marking ends, and ensuring proper overhang. 18:55 – Wetting Out the Joint (Two-Part Bonding) Applying unthickened epoxy and allowing it to tack. 20:10 – Thickening Epoxy with Colloidal Silica Creating a structural glue mixture with the right consistency. 21:00 – Applying Epoxy & Final Glue Spread Using a toothed spreader to ensure full contact and no trapped air. 21:48 – Setting the Joint & Preventing Slippage Anchoring ends, sighting alignment, and using cauls properly. 23:10 – Clamp-Up & Evaluating Squeeze-Out Ensuring a full bond without starving the joint. 24:20 – Epoxy Cleanup & Curing Advice Wiping excess, avoiding disturbing the glue line, and cure times. 25:50 – Choosing the Right Hardener (205, 206, 207, 209) Temperature considerations and Mark’s preferred setups. 27:02 – Why Repair Instead of Building a New Spar? Cost, materials, labor efficiency, and customer expectations. 28:40 – Alternatives to Long Scarfs (Bird’s Mouth & Finger Joints) How to shorten scarf length without reducing structural ratio. 30:10 – When to Use a Nib Scarf Why nibs work on rub rails but not spars. 31:00 – Final Results & Finished Scarf Inspecting the feather edge and the clean glue line. 31:40 – Closing Thoughts & Tips Recap of the method, benefits of simple jigs, and using quality epoxy.