Jinx: A Class B Outboard Racing Boat Plan in Plywood

Jinx is a small racer drawn around a specific engine class. It uses 1/4 in marine plywood for the bottom and sides, a lighter 1/8 in deck, a mahogany sheer guard and an aluminum fin, and it is built for a Class B outboard of 20 cu. in. maximum. The build is laid out across ten sheets from Mechanix Illustrated. It suits a young racer or hobbyist who wants to compete in a defined class with a light, carefully built hull.

Jinx at a glance

Detail	Jinx
Type	Racing boat
Construction	1/4 in. marine plywood bottom and sides, 1/8 in. deck, mahogany sheer guard; aluminum fin
Power	Class B outboard (20 cu. in. maximum)
First published	Mechanix Illustrated, p. 160
Plan sheets	10

Built light for racing

Racing classes reward weight savings, and Jinx shows that thinking in its 1/8 in plywood deck. The heavier 1/4 in marine plywood goes where the loads are, in the bottom and sides, while the mahogany sheer guard protects the edge from knocks. Every material choice is made with purpose, which is part of the fun of building a racer.

The aluminum fin helps the boat hold its line through turns, a big deal on a race course where sliding out costs time. Designing around a Class B engine of 20 cu. in. maximum keeps the project focused and lets builders compete fairly within that class.

The original plan sheets

These are the 10 original sheets, scanned from the magazine. For building, use the full-size PDF in the download section below.

Before you build

• Choose an outboard that fits the Class B limit of 20 cu. in. so the boat stays legal for its class.
• Mount the aluminum fin securely and check its fastenings before every race.
• Wear a helmet and life jacket and race only on organised, supervised courses.

Download the plan

Jinx comes as one file holding all ten original sheets, ready to print at full size or study on a tablet.

Download the complete plan (PDF, 10 sheets, 8.6 MB)