François Vivier Naval Architect
Stock plans: motor boats

You will find on this page my motor boats designs for amateur builders. Most of them may also be purchased "ready to sail" from authorised builders.  Up to now, I have designed few motor boats but I intend to propose other designs. See also other projects of motor and steam boats.

Ebihen 16 is a stable and seaworthy hull, with a generous freeboard, fitted with a well for an outboard motor. She is an excellent and beautiful motor boat for day sailing and fishing. The propeller is just ahead of rudder for good manoeuvrability. A 4 to 10 hp outboard motor may be installed. A large locker under fore deck allows stowage of boat and personal equipment. Ebihen can be built and stored during winter time in a common garage. It is of course trailerable. She is mainly made of plywood, for clinker planking but also backbone and transverse bulkheads, then easy to build by a first time amateur. Ebihen 16 is fitted with a water ballast tank (150 litres) improving seakeeping and trim. This is particularly interesting if you are sailing with a small crew. Filling and emptying of the water ballast is very straightforward. The boat, as well as a kit, is marketed by Icarai.

Product	Version	Ref	EU (VAT incl.)	Other countries	Availability in English
Study plan	All	EB16M-E	15 €	15 €	Available sept 2008
Building plan	Clinker	EB16M-D	220 €	185 €	Available sept 2008
Full size patterns	Clinker	EB16M-TC	250 €	210 €	Available sept 2008
Attention : full size polyester patterns of NC cut kit are necessary to build this boat
Plan content - Ordering a plan - Order form

Koulmig cabin

Hull/Waterline length:	5.90/5.45 m	Breadth:	2.20 m	Light weight (without motor):	600 kg	Motor:	10 to 40 hp

At several occasions, I have been asked to design a motor boat. Of course, such a boat had to be in the same spirit as my sail boats, inspired by tradition on one hand, adapted to today use and easy to build in the other hand. The main design parameter of a motor boat is speed. Today, most boats on the market are planing boats, able to be very fast, for example 30 knots for a 20' boat. There is several drawbacks with planing hulls. They are highly powered with an expensive motor and high fuel consumption. They generate huge waves even at low or medium speed. They are  fast, but very uncomfortable as soon as you have chop or waves. An other option is the displacement boat, as many fishing boats, but with a limited speed, let say 6 knots for 20' length. Between planing and displacement boats, there is a room for semi-planing boats. To make things simple, a planing boat has V shape sections, including at transom. Semi-planing boats have a flat transom avoiding suction effect at low speed. As a general rule, a semi-planing boat has a maximum speed, depending on power, between 2 to 3 times the speed of a displacement boat of same length. Some well known traditional boats were semi-planing, in particular American Maine coast bass boats (chined) and lobster boats (round bilge to ease pots handling). Many pilot boats were also very seaworthy semi-planing craft. However, all these boats have progressively evolved toward full planing, sacrificing to a general trend to go still faster. When Bruno Leducq, the builder of first Koulmig, ask me a design, I suggested to draw a semi-planing boat, giving a seaworthy boat at medium speed, well suited to comfortable cruise, fishing and even sailing in river with little wave making. Only a moderate power is needed. 10 hp for river, 20 to 30 hp at sea, giving a speed of about 14 knots. I consider that 40 hp is the very maximum for this boat. The prototype had a 50hp outboard but was too heavy. Motor vendors always propose you an excellent bargain with more power than asked for! So, better ask 20 hp if you need 30. You will get 30 at 20 hp price! The cabin gives accommodation for two, with a small galley and a stowage place for the porta-potti under cockpit. A dinner table may be installed either inside or in cockpit. The fore deck is lowered, giving good bulwark protection. A locker for the anchor line acts also as a seat facing forward. Four large lockers in cockpit allow ample stowage place for all gears. The full width self draining cockpit is ideal for fishing. Koulmig is built with plywood, epoxy sheathed. Plywood is far stiffer than grp and is the best material for motor boats. This gives a light hull, which is easily trailered, launched and retrieved. The hull is planked over a crisscross of transversal and longitudinal bulkheads. Full scale patterns on polyester film are sold by the designer. They give the shape of almost all parts. NC cutting of all parts is also possible. Other arrangements of this hull are considered. I have already studied a version with a steering wheel and motor remote control just aft of coachroof. A helmsman seat is arranged over a shortened locker.  After trials of the prototype, improvements to design have been implemented and plans, with building instructions, are now on sale by the designer. Plan package will be translated into english on demand. Koulmig is marketed by Icarai, a boat-builder located in Cherbourg, close to the car ferry terminal. Therefore shipping to UK, as well as visiting the builder is easy. Icarai is also selling a full set of materials and a NC cut plywood kit for amateur builders. Professional construction in other countries is thought of and I will be happy to get in touch with interested boat-builders.

Product	Version	Ref	EU (VAT incl.)	Other countries	Availability in English
Study plan	N/A	KOU-E	15 €	15 €	Please ask for delivery time (about 1 month)
Building plan	N/A	KOU-D	380 €	320 €	Please ask for delivery time (about 1 month)
Full size patterns	N/A	KOU-TB	580 €	485 €	Available
Attention : full size polyester patterns of NC cut kit are necessary to build this boat
Plan content - Ordering a plan - Order form

Koulmig runabout and fishing

Hull/Waterline length:	5.90/5.45 m	Breadth:	2.20 m	Light weight (without motor):	600 kg	Motor:	10 to 40 hp

On the same hull than the cabin version, and with the same benefits, I have drawn a classic runabout version of Koulmig, with excellenbt seakeeping abilities. Very elegant, she is able to carry a crew of 7 for day sailing. Inside arrangement my be tuned to your preferences. On the same structure, it is also possible to replace the windsreeen by a small wheelhouse. Then you have an excellent fishing boat you may build in your garage or buy to a boatbuilder. A first unit of Koulmig runabout is under construction in France. Plan package will be translated into english on demand. Koulmig is marketed by Icarai, a boat-builder located in Cherbourg, close to the car ferry terminal. Therefore shipping to UK, as well as visiting the builder is easy. Icarai is also selling a full set of materials and a NC cut plywood kit for amateur builders. Professional construction in other countries is thought of and I will be happy to get in touch with interested boat-builders.

Product	Version	Ref	EU (VAT incl.)	Other countries	Availability in English
Study plan	N/A	KOR-E	15 €	15 €	Please ask for delivery time (about 1 month)
Building plan	N/A	KOR-D	380 €	320 €	Please ask for delivery time (about 1 month)
Full size patterns	N/A	KOR-TB	580 €	485 €	Available
Attention : full size polyester patterns of NC cut kit are necessary to build this boat
Plan content - Ordering a plan - Order form