Swift Swoose: A Free Plan for a 10 ft Tunnel Catamaran

Swift Swoose packs surprising space and speed into a 10 ft (3 m) hull. It is a twin-hull catamaran with a lift tunnel between the hulls, and its 5 ft (1.5 m) beam leaves room for four people. Air trapped in the tunnel helps lift the boat at speed, and the plan quotes up to 45 mph. Few small runabouts manage to be this roomy and this lively at once.

Swift Swoose at a glance

Detail	Swift Swoose
Type	Catamaran runabout
Length	10 ft (3.05 m)
Beam	5 ft 1/2 in (1.57 m)
Capacity	4 persons
Construction	Plywood over framework; twin-hull catamaran with a lift tunnel
Power	5–25 hp outboard; up to 45 mph
First published	1978 edition, p. 73
Craft Print	No. 199
Plan sheets	5

What the tunnel does

The lift tunnel between the two hulls traps air as the boat moves, adding lift and reducing the wetted surface. That is how a short, beamy boat can reach speeds normally reserved for longer, slimmer runabouts. It is a neat bit of design thinking packed into a boat that still fits in a single-car garage.

A wide catamaran stance also makes the boat steady, so four passengers can sit comfortably. Plywood over framework keeps construction familiar, and the outboard range of 5 to 25 hp lets you choose between relaxed and quick. That range makes it equally suited to relaxed family outings and spirited runs.

The original plan sheets

These are the 5 original sheets from 1978, scanned from the magazine. For building, use the full-size PDF in the download section below.

Before you build

• Keep both hulls perfectly symmetrical; any difference will make the catamaran pull to one side.
• Respect the 5 to 25 hp outboard range and fit a stout transom across the tunnel.
• Add flotation in both hulls so the boat stays level if one takes on water.

Download the plan

All five original Swift Swoose sheets in one file, with the twin hulls and tunnel drawn in full.

Download the complete plan (PDF, 5 sheets, 3.1 MB)