Cat boat 12 by

[C12] A fast but stable cat boat

Length overall12'3.63 m
Beam5' 3"1.6 m
Weight119 lbs54 kg
Sail area78 sq. ft.7.20 m2
Hull construction Stich-n-glue



When we researched the design of an easy to build, easy to sail 12' cat boat with a marconi sail, we found probably 20 examples in our library. From the Penguin to the Cherub plus a dozen other boats in the same style, this was nothing new except that none combined modern materials with ease of building. All were old fashioned plywood on frame designs except of the Cherubs but those ones were not easy to build.

The Bruce Farr designed Cherub was one of the best but we liked the low chine of some others and the result is our Cat 12. Not as complicated as the Penguin, probably a better sailor too, she is without doubt much easier to build and to sail.

The wide beam will provide good forgiving stability to a beginner but as he gains experience he will enjoy the performance potential and maybe be race her against other boats of her size.

The ideal crew is one or two persons.

The wide seats will be comfortable for relaxed sailing but the plans also show a 3" (75mm) wide rubrail to sit on in strong winds.

A couple of nice features are worth mentioning. The halyard is used as a forestay: it returns to a block at the bow, inside the hull and from there to the mast. That block is fastened to a strap on the inside thread of the bow U-bolt: we save one nut and one washer! The swept back shrouds go to a Do-It-Yourself rigging screw on the rear side of the mast partner. The plans show how to make such a part from an eye bolt and a wing nut. One can also use plain lashings. The lifting system for the centerboard does not use any hardware, see our HowTo file at for a description.

The plans show two sails and four different spars. Each sail is 77 sq.ft., marconi type (= triangular)

  • The "standard" sail plan uses a regular aluminum profile. Dimensions and part numbers are given on the plans. Battens and reef line are optional.
  • The sprit sail plan uses almost the same triangular sail shape: this is not the same sprit sail as in our PK78 etc. Here, the sprit replaces the boom. There should be no major performance difference between the sprit sail and the standard sail. It may even perform better with the carbon fiber mast, see below.
  • The economical version of the sail plan combines a sprit sail with a wooden mast and wooden sprit. Solid wood or hollow: all the dimensions are on the plans. No hardware at all required for that sail plan.
  • A performance variation of that sail plan uses a 6 kg (14 lbs) carbon fiber mast. The specifications are listed but marked "experimental". It is a proven carbon fiber mast, similar to those used on racing Cherubs but it's fabrication require more skills than a wooden one: vacuum bagging for example.
  • Each mast can be made as a rotating mast to improve performance even further. The plans show a Delrin sleeve and mast step pivot. This is an option.
  • Each sail plan shows the sheet, blocks, cleats, traveler (=horse) and all details needed to rig the boat plus exact sail, running and standing rigging dimensions.

All these options can be combined to customize your boat: build her as simple or as sophisticated as you want.

A last option is a locker in the rear compartment: we show how to cut and make a lid.

Cat boat 12

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