Design Background

Insider is the product of my third collaborative venture with Frank Smoot, the designer and builder of some of the best small sailing trimarans around ( We both wanted to design and build a small but versatile sailing dinghy that was also suitable for rowing and power by small outboard, so we agreed to contribute our joint skills.

This is the result, 'Insider', so called because she was also designed to fit inside Frank's Dodge Grand Caravan (in Europe known as a Chrysler grand Voyager). She should fit in the back of most MPV's, vans or pick ups.

The Insider Dinghy is short enough and light enough to easily be handled by just about anyone. The hull is a planing design, so if you have the capability and guts, it will probably go faster under sail or outboard power than most other dinghies in its class. It’s also a delight to row, as the slender hull and comfortable seating position combine to optimize your ‘human-power experience’.


The simplest way to build the Insider Dinghy would be as a rowing / outboard boat. It would be about 20 lbs lighter than the centerboard and daggerbard sailing versions.

If you’d prefer to sail, you can set it up with a pivoting centerboard or a daggerboard, and add the rudder and mast steps. Now you can not only enjoy sailing it, but also have the option of rowing or motoring!

Sail Rig Options

Many builders of small sailing boats will already have several sail rigs. If that’s you, then you can most likely power the Insider Dinghy with a rig you already have. That alone can save as much as half the cost of building a small sailboat.

The rig shown in the photos and plans is a 65-sq. ft. leg-o-mutton rig with boom and loose foot. But most rigs from about 50 to about 75 sq. ft. would probably work just fine, because there are three separate mast locations spaced 7” apart. This allows you to use the mast location that works best (balances the helm) with your particular sail rig. And if you opt for the pivoting centerboard, you get even more helm-balancing flexibility.

The hull construction is basic stitch-and-glue plywood. Frank used 3mm ply (because he already had it) for parts of the Insider Dinghy hull you’ll see in the photos, but it’s really a bit too thin and flimsy for this particular boat and any weight saved will be regained because it all would need to be glassed, preferably on both sides.

We recommend using 5 or 6 mm ply everywhere. You can get away with glassing just one side, or if you plan to be extremely gentle with it, just glassing the seams and epoxy-coating the rest. But whatever plywood you end up using, just make sure the glue is waterproof. I personally do a boil test - just to be sure.

Plywood List

6 sheets of 5 or 6 mm

¼ sheet of 1/2”

Plans Include

An extremely detailed construction manual including 200 photos detailing the complete building process, with over 70,000 words of explanatory text by Frank Smoot.

A separate drawings manual with (for the centerboard version), 48 drawings prepared from a 3D CAD model by Andrew Walters.


Length Overall: 11’ 7”

Beam: 48”

Max. Depth Amidships: 24”

Hull Type: Planing, 6-panel, plywood

Number of Occupants: One to four

Speed Under Sail: 10+ mph (in skilled hands)

Speed Under Power: 12+ mph with 3.5 hp outboard

Weight w/ Centerboard and Trunk: Approx. 100 lbs (45.5kg)

Weight With Rudder and Sail Rig): Approx. 125 lbs (56.8kg)

Max Loaded Draft Fully: Approx.4”

Sail Rig: Cat rig with freestanding / unstayed mast and 65 sq. ft. leg-o-mutton sail with foot boom.