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  • Study plans are extracts from the plans allowing the buyer to have a more precise knowledge of the plan content. If you are ordering the building plan, you do not need to order the study plan.
  • The Building plan is the basic document to build the boat. It includes a free telephone or e-mail assistance.
  • Full-size patterns, or kit, are required to build this boat.
  • It is possible to buy a kit from one of my partners.
  • Postage and VAT, if applicable, are included in the shown prices.


Pilot house cruiser, semi-planing hull, outboard motor, 7 m long

Hull length / waterline  6.98 / 6.50 mSail area  0
Breadth / waterline  2.50 / 2.20 mOutboard motor  30 to 60 hp
Draugth  0.38 mDesign category / Crew  C6
Light weight without/with motor  1 100 / 1 220 kgBuilding time with plywood kit  1000 hours

This plan is available in French only. If you would like to order an English version, please get in touch with the architect. Attention: this boat may be built only with a numerically cut plywood kit or with full size patterns. Due to the high number of plywood panels, the kit is recommended.

Drawing (version A) Drawing (version B)

Koulmig 23 is a power cruiser with a classic and straightforward look, simple and light plywood construction, easy maintenance, and designed for both professional and home builders. The boat’s aesthetic is reinforced by shaped sides (flared bow and tumblehome aft). It is a boat small and light enough to remain transportable. It offers sleeping space for 2/3 people. There is a galley area with a sink and stove. Toilets are in the fore cabin, separated from the wheelhouse.
There are two versions, A and B. Version A has a spacious cockpit. You can fish there comfortably, sunbathe or set up a table at anchor. Version B has an extended wheelhouse and an actual toilet/shower room for more comfort.

Hull lines, motor

Koulmig 23 is a semi-planing boat optimized for a speed range between two and three times that of a displacement hull. The power required is less than that of a planing craft. The vertical bow extends the waterline. The aft lines are flat, reducing waves-making at low speeds. The maximum speed is 12 to 15 knots, sufficient to navigate slightly rough seas. A 50 hp (around 100 kg) outboard motor is enough to get the most out of this hull and the boat’s moderate weight.
Koulmig 23 is, therefore, a low-consumption boat, well in tune with the times.


Koulmig 23 is made of epoxy plywood. The bottom planking is a large developable panel. The sides are made of cold-moulded plywood set on longitudinal stringers. The hull thickness is 12mm, epoxy sheathed outside. This construction saves a significant weight compared to a polyester construction (about 200 kg). In addition, it is easy to implement, especially with plywood parts cut on a CNC machine.


We wanted to take full advantage of the wheelhouse space to make it a place where we could stay pleasantly at sea and in port. To this end, we have provided a dinette on the port side, which allows two people to sit there. Extending the table and removable seats to accommodate up to 4 people is possible. The dinette may be converted into a berth with an extension at the fore-end.
In the fore cabin, we have two berths of perfect length. A small porthole overlooking the lowered foredeck provides light and ventilation. It may be completed with a deck panel.
The toilets are to starboard (Porta-Potti chemical toilet). A curtain provides the necessary separation from the wheelhouse.

A transverse seat at the aft end of the cockpit offers a substantial storage volume. The fuel tank is located under the cockpit.
Removable boards, which can be stowed vertically along the side, form a beautiful L-shaped seat for enjoying meals outside with a folding table. Its length allows using it as an extra berth. Fitting a closed cockpit tent can significantly improve the boat’s comfort for those who wish to live on board for a few weeks. A transom platform, on either side of the motor, may be built to facilitate boarding and swimming.


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