Hartley Trimaran Designs – Features

Hartley Trimaran Designs – Features

Design Features (Français)

Science Transformed Into Art

 Hartley Trimaran Designs are the most advanced designs available. Derived mathematically and completed using a computer aided engineering (CAE) program, designed to address all the engineering problems associated with multihulls designs. All the  computer programs (CAE/CAD),  were written in house, embodying knowledge learned from many years of sailing and engineering experience.  Trimarans were chosen to be the best for all around sailing because they involve the least design compromises, when trying to achieve speed , safety and comfort.

  • All surfaces hull, deck, keel, rudder and sail are derived mathematically , their databases are then used throughout the CAE (computer aided engineering) program , for further development and study of the design. Using this design approach provides for very accurate determination of all engineering parameters, such as center of buoyancy, center of gravity and  design displacement.  Very accurate data for dimensioning drawings and final construction, is one of the other many benefits. The tables of offsets are accurate to 1/32 of an inch. All drawings have accurate scaled rulers,  for dimensional takeoffs. Software is also supplied with which all drawings, tables of offsets and engineering design data can be viewed.   Dimensions, object locations, line lengths, areas and their centroids, any cross sections can be viewed/determined using this software. Click on a line/dimension and you know it’s length, click on a deck hardware object and you know it’s location, define an area with clicks and you know how many square feet of plywood you need. If you want an intermediate section drawing, not supplied with the plans, move the cursor to that section location and click, you have it  This is a great builders tool, it will save you time and money during construction..
  • All designs are centerboard shoal drafted sloop and single-handed rigged. Cruising comfort with adequate load carrying capacity for extended cruising are the main design criterion. The hulls sections are parabolic and the displacement curve follows a cosine function. The parabolic section give a large volume for a low wetted surface and the cosine displacement gives a constant acceleration/deceleration from point to point on the hull surface preserving laminar water flow. The velocity prediction program, (See VPP Graphs)   considers all the parameter effecting performance on different points of sail from a broad reach to beating to windward.  The VPP was extremely difficult to write, but results have been substantiated with 381 model testing.  If anything the VPP is conservative in it’s predictions, which was the intended approach.  Throughout the overall design approach has been conservative.
  • Generous storage space for stores, sails, and ground tackle, etc. is provide in the way of wing lockers, beam lockers, overhead lockers, galley bins, head bins, wet lockers, anchor rode lockers and under forebunk /settee lockers. In the cockpit are lockers for the storage of propane, outboard and inflatable dinghy. Sails can be stored either in the Amas(floats) or in the lazaret. In the engine room tools and mechanical parts can be stored on the water heater shelf. There is ordered storage space for all your cruising needs and supplies.(See Design Drawings)
  • On deck there are no dorades or other lines fouling obstructions. Ventilation is provided by hatches and under wing vents, which can be closed in inclement or cold weather to completely seal the boat. The decks provide a spacious almost level platform for all deck chores. The windward deck when healed is almost completely level. Cockpit seats are long and wide enough for sleeping. Some would say this is an old sailors’ boat, you don’t have to be old to be wise. All designs are all weather, go anywhere boats (The ICW , locks and most rivers{2 feet or more depth}). The shoal draft and beachability opens up many possibilities for moorings and maintenance.  If you have a mooring in a dry-out tidal zone, let her set on the bottom at low tide.
  • All design can be built in modules. The beams, hull structures and interior are completed then transported and assembled at the coast.

Allan Hartley
Designer and Engineer

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Last modified: May 10, 1999