Fire Fly: A 1948 Stepped-Hull Outboard Runabout Plan
A 14 ft stepped runabout from 1948 for up to six, built for 15–50 hp outboards and reported near 60 mph.
Fire Fly is where a family runabout meets a race-bred hull. Dating from the 1948 edition of the Boat Builder's Annual, it is 14 ft (4.27 m) long, just over 5 ft (1.5 m) wide, and seats up to six. The secret is a stepped hull with a vented step, which lifts the boat and cuts drag at speed. Rated for 15–50 hp outboards, it reportedly reaches about 60 mph with an Evinrude Big Four. Thirteen detailed sheets make it a serious, rewarding build.
Fire Fly at a glance
| Detail | Fire Fly |
|---|---|
| Type | Outboard runabout |
| Length | 14 ft (4.27 m) |
| Beam | Just over 5 ft (1.52 m) |
| Capacity | Up to 6 persons |
| Construction | Stepped hull with vented step |
| Power | 15–50 hp outboard; up to about 60 mph with an Evinrude Big Four |
| Designer | William D. Jackson |
| First published | Boat Builder's Annual, 1948 edition, p. 5 |
| Craft Print | No. 55 |
| Plan sheets | 10 |
What makes it quick
A step in the bottom breaks the hull's contact with the water, and venting it lets air in behind the step to reduce suction. The result is less wetted surface and more speed from the same engine, a trick borrowed from racing hulls and fitted here into a boat that can still carry six.
That wide power range is useful. With a 15 hp motor Fire Fly is a lively family runabout, while the upper end of the range turns it into a genuinely fast boat. Thirteen sheets give plenty of detail for getting the step geometry right. Builders who enjoy precise work will find this one deeply satisfying.
The original plan sheets
These are the 10 original sheets from 1948, scanned from the magazine. For building, use the full-size PDF in the download section below.
Who designed it
William D. Jackson designed Fire Fly for the Boat Builder's Annual, 1948 edition, page 5, as Craft Print 55. Jackson was a mainstay of the Craft Print series, and this early design shows his interest in performance hulls.
Before you build
- Stay inside the 15–50 hp outboard range and build up to higher power gradually as you learn the hull's handling.
- Build the step and its vent exactly as drawn, since small errors there change how the boat behaves at speed.
- Wear life jackets and keep a kill-cord attached; a stepped hull at high speed needs full attention.
Download the plan
The 1948 Fire Fly plan as a single file: all thirteen sheets at full size, ready to print or use on a tablet.
Download the complete plan (PDF, 10 sheets, 2.8 MB)
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