Sven Yrvindvideo
The Stirrup and the Balanced Lug Are Equally Ingenious.
January 15, 2026 · 7 min · 2K views
What this video covers
Sven Yrvind is constructing a shallow-draft, high-latitude sailboat designed for a 14,000-mile nonstop circumnavigation through the Southern Ocean.▶ 0:19 The vessel utilizes a balanced lug sail rig, which Yrvind configures with a 11-degree forward rake to achieve self-stabilizing characteristics similar to aircraft wing geometry.▶ 2:52 This design places the driving force ahead of the center of resistance, allowing the boat to maintain course without mechanical self-steering systems like wind vanes or autopilots.▶ 5:35 To secure the boom and prevent it from rising, Yrvind installs a downhaul system featuring adjustable plywood anchor points.▶ 3:06 He glues these plywood mounts to the hull, incorporating three holes per mount to provide tension adjustment.▶ 3:27 The setup includes dedicated port and starboard downhaul attachments accessible from the hatch.▶ 4:13 Yrvind draws a historical parallel between the mechanical advantage of the stirrup in Mongol warfare and the functional simplicity of the lug sail downhaul.▶ 1:54
More from Sven Yrvind
From Sven Yrvind — see the channel’s boat, crew, and every analyzed video.