D18 - Myst:An 18-Foot
Beach Yawl
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B.C.
D18 - Myst:
An 18-Foot
Beach Yawl
Notes:
Building plans consist of 11 sheets of computer generated drawings: Six paper prints, drawn to a scale of 1" = 1’- 0"; and Five, full-size, ink jet prints plotted onto transparent Mylar film. No lofting is required. The Mylar sheets provided full size patterns for all major structural components, including moulds, frames, floors, foils, hardware, etc. This makes transferring the lines directly to the building materials a straight forward and easy task, saving the builder considerable time and effort during the construction process and minimizing the possibilities of error.
Drawing #1403 (included with the study plans) shows details of the construction jig and also provides small scale patterns for making a flotation model. This may be useful for the first time builder and can aid in understanding how the boat is to be put together, without first incurring the expense of building a full-sized hull. This model can be as simple or as complex as desired.
The design brief for "Myst" called for a moderately narrow hull, with an emphasis on good performance under sail throughout a wide range of weather conditions that might be encountered during offshore passages on the North American Great Lakes and along the Atlantic Seaboard. Extreme shallow draft was also desired, so that the boat could be easily trailed and launched off the beach in areas with very shoal water. Hence the need for some ballast to help the hull stand up to the generous sail plan. There is also considerable tumblehome designed into the hull to capitalize on a greater waterline beam and the higher initial form stability that it affords.
Any qualms about carrying ballast in an open boat are addressed by built-in buoyancy tanks to provide sufficient flotation to keep the boat afloat in the event of a capsize. This, coupled with the extra flotation provided by waterproof storage bags, should give the crew considerable peace of mind out on the water.
The lug yawl rig was chosen because of it’s inherent ability to adapt to variable wind conditions quickly and efficiently. In a squall, sail area can be dramatically reduced by simply dropping the main and carrying on under jib and mizzen. Or the boat can just as easily be sailed under main alone. Either combination will balance. The centre of effort of the sails in any one of these configurations will fall on the same vertical plane as that of the boat under full sail.
Hard on the wind, the hull can be balanced by trimming the mizzen - in effect, using it as a steering sail. The big centreboard also has a wide range of travel and can be adjusted to help balance the hull. Playing both in combination can trim out the helm and induce some degree of self-steering on most points of sail. All the running rigging can be led aft to the helm for singlehanding.
Inside, the layout is designed in such a way that all the cruising gear can be stowed beneath the thwarts, leaving the area above free of clutter. The central thwart area can be closed off with hinged side benches to provide a sleeping platform large enough for two people to rest on comfortably. This doubles as a deck underway and makes it very easy for the crew to move about the boat without worrying about treading on equipment and supplies stowed below.
Stripped of sail, the masts can be used to support a full length boom tent over the living area. The tent can be arranged so that it overlaps the coamings and any rainwater would then be deflected over the side, keeping the interior snug and dry. Another option would be to simply set up a regular, free standing, dome tent on the sleeping platform. This would have the advantage of providing better protection for the crew in areas where insects are a problem. It would also save on the expense of a much larger, custom-made boom tent and could be used ashore, if desired.
Many other features have been borrowed from Alaska, including the wide, plank keel for ease of beaching, and the two-point, endless-loop anchoring system that makes mooring and handling the boat from shore an easy job.
There is provision for an auxiliary outboard motor to be mounted on the transom. Long shaft models up to 5 HP can fitted, though a 2 or 3 HP engine should be more than adequate to drive the hull at speed. For those who dislike motors, a pair of well balanced 10’ oars have been designed to move the boat along nicely in light conditions.
Construction is epoxy-glued, strip-planking over laminated frames and longitudinals. Planking is 5/8" x 1" wooden strips - sealed, inside and out, with epoxy resin. Exterior fibreglass sheathing is optional, but not required structurally. This boat is intended to be economical and straight forward to build by an amateur possessing reasonable woodworking skills. A detailed 35 page building text is included with the plans. It is highly recommended that this be further supplemented with the the Gougeon Brother's book on Boat Construction for those with little experience using epoxies or building boats.
Two of these craft are currently under construction. Photos and notes of their progress and their sea trials will be posted on the Web Site as they are made available. Myst’s construction is similar in many ways to that of Alaska and a detailed sequence of that building process can be viewed on the Gallery page.
Consultation is provided at no extra cost with the purchase of building plans
Please note: At this time, plans are only available in Imperial Measurement (feet and inches).
Specifications:
LOA 18’- 3" 5.5 m. LWL 17’- 4" 5.3 m. Beam Max 5’- 7" 1.7 m. Beam LWL 4’- 8" 1.42 m. Draft at LWL Board up 0’- 9" 0.23 m. Board down 4’- 0" 1.22 m. Displacement: LWL 1200 lbs. 544 kg. Maximum 1600 lbs. 725 kg. Weight (hull) 400 lbs. 181 kg. Ballast 400 lbs. 181 kg. Sail Area: Total 160 sq. ft. 14.86 sq. m. Main 103 sq. ft. 9.56 sq. m. Mizzen 21 sq. ft. 1.95 sq. m. Jib 36 sq. ft. 3.34 sq. m. Wetted Area 109 sq. ft. 10.12 sq. m. PPI 300 lbs. 136 kg. Prismatic Coefficient .536 Disp/Length 112 SA/Disp at: 1200 lbs./ 544 kg. 22.6 1600 lbs./ 725 kg. 18.7
Copyright 2003
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