François
Vivier Naval ArchitectStock plans: motor boats
François
Vivier Naval ArchitectYou 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.
| Hull/Waterline length: | 4.50/4.24 m | Breadth: | 1.85 m | Light weight (without motor): | 320 kg | Motor: | 5 to 10 hp |
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Ebihen
15 was designed as a sail boat. She is a stable and
seaworthy hull, with a generous freeboard, fitted with a well for an
outboard motor. Thus she is also an excellent and beautiful motor boat
for day sailing and fishing.Plans of the motor version, without centreboard and rig, will be modified on demand. It is even possible to fit a small diesel engine if preferred. Please ask the designer. Ebihen may be built as a strip planked or a clinker hull.  See
Sail version
for more detail and prices.The boat, as well as a kit, is marketed by Icarai. |
| Hull/Waterline length: | 5.90/5.45 m | Breadth: | 2.20 m | Light weight (without motor): | 600 kg | Motor: | 10 to 40 hp |
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  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. Other arrangements, including with diesel engine, are also possible and may be designed on demand. After trials of the prototype, improvements to design have been implemented and plans, with building instructions, are now on sale by the designer. 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.
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| 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 | 480 € | 400 € | Available |
| Attention : full size polyester patterns of NC cut kit are necessary to build this boat | |||||
| Plan content - Ordering a plan - Order form | |||||