Sea Lark: A 14 ft 6 in Inboard Utility Boat Plan for Five
William D. Jackson's 14 ft 6 in inboard utility boat for five, built in 3/8 in plywood and good for 10–20 mph.
Sea Lark brings inboard comfort to a manageable size. This 14 ft 6 in (4.42 m) boat with a 5 ft 6 in (1.68 m) beam seats five and runs on an inboard engine of 10–25 hp, reaching 10–20 mph. The hull is 3/8 in plywood over a frame drawn with developable surfaces, so the panels bend naturally into place. It suits families who want a steady, dry boat for lake outings and fishing, with the engine tucked inside rather than hanging off the stern.
Sea Lark at a glance
| Detail | Sea Lark |
|---|---|
| Type | Utility boat |
| Length | 14 ft 6 in (4.42 m) |
| Beam | 5 ft 6 in (1.68 m) |
| Capacity | 5 persons |
| Construction | 3/8 in. plywood over a frame with developable surfaces |
| Power | Inboard 10–25 hp; 10–20 mph |
| Designer | William D. Jackson |
| First published | Boat Builder's Handbook, p. 24 |
| Craft Print | No. 228 |
| Plan sheets | 8 |
The inboard advantage
An inboard engine sits low and central, which helps balance and leaves the transom clean for swimming or fishing lines. With 10–25 hp on hand, Sea Lark has enough power for steady cruising without the noise and thirst of a big engine. Five seats make it a true family boat, with space for a cooler and fishing rods as well.
Developable surfaces mean every plywood panel bends in just one direction, with no compound curves to fight. That makes a 14 ft 6 in hull realistic for a careful amateur, and the 3/8 in plywood gives a solid, reassuring feel underfoot when five people are aboard.
The original plan sheets
These are the 8 original sheets, scanned from the magazine. For building, use the full-size PDF in the download section below.
Who designed it
William D. Jackson designed Sea Lark for the Boat Builder's Handbook, where it appears on page 24 as Craft Print 228. Jackson stands among the busiest designers of the Craft Print series and favoured plywood hulls that home builders could shape without steam or special tools.
Before you build
- Plan the engine bed, shaft log and stern bearing alignment carefully, since inboard installs depend on getting the shaft line true.
- Ventilate the engine space well and keep fuel lines away from heat, as an enclosed inboard needs fresh air to run safely.
- Fit the engine within the 10–25 hp range shown, which suits the 10–20 mph the hull was designed for.
Download the plan
Sea Lark's eight original sheets come in one file, sized to print or read easily on a workshop tablet.
Download the complete plan (PDF, 8 sheets, 6.7 MB)
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