Marissa Eco 18
Click here for Construction photos
Click here to see pictures of a customized Marissa
Marissa driving her name-sake.
This page is reproduced with permission from author Matt Murphy and WoodenBoat Publications.
The Marissa is a smaller version of our Ocracoke 20. The design goal was for the most economical center console boat that would be just big enough to be really practical.
By keeping the top end speed at 25 knots the structure could be made lighter which in turn, allow for a smaller motor and less fuel which would allow for a lighter hull and a smaller motor and less fuel. Calculations show that at 15 knots (17.27 mph) with the 25 hp motor, the 16 gallon (60 liter) fuel tank will give a range of 210 nautical miles in flat water for 15mpg which is more than a lot of pick-ups can do. The top end speed with a 25 hp motor is 21 knots or 24 miles per hour burning 2.2 gallons (8.3liters) an hour.
The cockpit slopes aft and is self draining.
|LOA………..18′ 0″ 5.49mLWL………..15′ 3″ 4.65m
BEAM…….. 6′ 10″ 2.08m
DRAFT/ hull.. 8 3/4″ 22cm @ dwl
DEADRISE at transom… 12 degrees
HORSEPOWER…… 25 – 60
BOAT WEIGHT including 25 hp motor, fuel and normal gear…1050-1150# (480-520 kilos) depending on materials and options*
DISPLACEMENT 1680 lbs (764 kilos) @ dwl
Pounds Per I” immersion 335# (152kilos)
*weight @ designer’s suggested materials; different plywoods plus different fiberglass weight and optional gear will change boat weight.
The boat uses developed panels of plywood, built over a jig. This means that hull panels can be full size and will drape over the frame without having to be cut into smaller pieces. All of the “jig” becomes permanent structure. The construction employs a modified “orange crate” method that is both light and strong. Note that this boat is aimed at efficiency of materials for performance, but is not a stitch and glue “introduction to building type of boat” if built from plans which includes full size patterns for the “jig”. We can also supply CNC cut kits for these components, so the build is very suitable for the competent amateur. This model would also be an excellent choice for the small commercial yard.
The drawing at left shows the unique step chine construction that we developed for this design. Instead of the chine log set “normal” to the side surface as is normally done, we set a chine batten “normal” (flat) to the bottom surface. This eliminates all beveling of the chine and gives a strong anchor to clamp or fasten the bottom to while the epoxy dries. The chine flat shape has been calculated and is machine cut or traced from the full size templates and rests on the frame flats until they are filleted. The side panels lay up to the chine flats and are trimmed to the flats after the glue dries. This method beside being fast to build will make for a very fair chine line and fairs right into the bow eliminating an unsightly unfair bow profile.
|The drawing at left shows all of the plywood parts for the kit nested in standard sheets of ply and ready for CNC cutting. There kit uses 15 sheets of 3/8″ (9mm) 4 sheets of 1/4″ (6mm) and one sheet of 1/2″ (12mm). All plywood is BS1088 OkumeThe kit includes all of the hull pieces, (with all frames, stringers, floors etc..) including (shown below) the stem and keel and the center console.
We can also offer an epoxy kit, 21 gallons of epoxy, 3 pumps, 2 pounds of coloidal silica, 1 pound of microspheres, glass and tape.
The Kit version is not built on a jig as the above drawing shows but is built on the cockpit sole where the frames fit into slots in the sole and the bottom stringers and keel slot into the frames.
Plywood kit price shown above is $3480.00 FOB our shop, shipping is via truck.
The Carteret County Community College, located in Morehead City, NC, has chosen the Marissa, the eco 18, as the teaching model for their boatbuilding program. Because the boat’s construction can be used to teach both traditional wood skills and CNC technology (also taught at the college) it embraced the full scope of the building program.
Follow the students and the building program at their blog: