GLBBS

18′ Lapstrake Speed Boat

Completed Project

A composite built 18′ lapstrake speedboat.

PROJECT SCOPE

Similar to the 1960’s vintage Thompson, Lyman and Chris-Craft utility runabouts. Originally designed for traditional marine plywood lapstrake planks over steam-bent oak frame construction, the changes to be incorporated into the GLBBS-built boat include:

  • Increased length to 18’
  • Cold-molded, strip-planked Northern white cedar bottom, ¾” thickness.
  • Epoxy glued, marine plywood lapstrake topsides, 3/8” thickness.
  • Laminated Sapele stem
  • Sawn marine plywood frames and bulkheads

STUDENT LEARNING EXPERIENCE

  • Lofting, including design changes
  • Making and setting up molds from lofting
  • Strip planking(bottom)
  • Glued lapstrake topsides
  • Reinforcing wood hull with fiberglass cloth set in epoxy resin
  • Scantling modifications for composite construction
  • Yacht joinery
  • Yacht finishing
  • Sea trials

PARTICULARS

  • LOA: 18′-0″
  • LWL: 16′-8″
  • Beam: 6′-6″
  • Draft: 10¼”
  • Displacement: 1,280 lbs.
  • Power: 60HP

DESIGNER

REFERENCES

CONSTRUCTION

  • Backbone: Fir keel, Sapele stem
  • Frames: Sawn ¾” marine plywood
  • Floors: Sawn ½” marine plywood
  • Transom: 1 ½” marine plywood with cold-molded Sapele veneer
  • Planking: ⅜” marine plywood
  • Gunwale Cap: Douglas fir
  • Interior: Sapele & Iroko
  • Coamings, Rails, Fife Rail, Bowsprit Knees, Stern Sheets: Sapele
  • Deck Frame: ¾” marine plywood
  • Deck: ⅜” marine plywood
  • Sole: Iroko
  • Fastenings: Stainless
  • Hardware: Stainless
  • Engine: 60HP four-stroke outboard
  • Auxiliary Engine:
  • Finish:
    • Hull: Linear polyurethane(LPU)
    • Bottom: Anti-fouling bottom paint
    • Deck: LPU
    • Interior: LPU