Boats
Boats and Boatbuilding INTRODUCTION
BASICS OF BOAT DESIGN
Buoyancy and Weight
Trim and Stability
Structure
Watertightness

SKIN AND BARK BOATS

WOODEN BOATS
Lapstrake Construction
Carvel Construction
Plywood Construction

CANVAS-COVERED BOATS
ALUMINUM BOATS
FERROCEMENT BOATS
FIBERGLASS BOATS
MEASURING AND MODELING
The Half-Model
Lift Models and Lofting

BOAT PROPULSION
Inboard Motors
Outboard Motors
Water-Jet Drive
Surface-Piercing Propeller

Motor-Boat Racing
Rowing
Yachting

Ships
THE EARLIEST SHIPS
Earliest Sailing Vessels
Galleys
Biremes
Triremes
Roman Galleys
Dromons
Lateen-Rigged Ships
Junks
Viking Ships
Cog
Carrack
Caravel
Galleon
East Indiamen
Ships of the Line
Frigates, Sloops, and Brigs
Clippers
Last Days of Sail
FUEL-POWERED SHIPS
Paddlewheel Steamships
Innovative Ships of the Late 19th Century
The Screw Propeller
Iron and Steel Hulls
Double- and Triple-Expansion Steam Engines
Steam Turbines
Diesel Engines
The Great Ocean Liners
Cruise Ships
Cargo Ships
Container Ships
Roll-On-Roll-Off and LASH Vessels
Tankers
Crude Carriers
Product Tankers
Other Specialized Tankers
Tanker Safety
Fishing Vessels
Trawlers
Seiners
Long Liners
Research Vessels
Hovercraft
The First Nuclear-Powered Vessels
Naval Vessels
Aircraft Carriers
Battleships
Cruisers
Destroyers
Frigates
Mine Craft
NEW TRENDS IN SHIP DESIGN
SUBMARINES
Submersible Craft
Torpedo (weapon)
shiptravel.auuuu.com Index

BOATS: Lift Models and Lofting


By the middle of the 18th century, builders had developed another type of model, consisting of a blackboard cut to the shape of the hull profile, with the sections formed of thin plank secured at the desired mold stations. The sections were made fair, or capable of being planked smoothly, by battens at suitable locations. Finally, about 1795, the so-called lift model was developed, made of boards of equal thickness pegged together and shaped to the desired hull form. The shape of the mold frames was obtained by taking the model apart and tracing the shape of the lifts, or planks, in their proper relation to one another. By drawing lines across these shapes at frame stations, the transverse widths at the ordinates formed by the lift thicknesses could be determined. The lift model is still in use in many boatyards and remains practical for small craft.

Lofting consists of drawing the full-size shape of the hull on a suitable platform or floor. The required drawing shows the mold sections, or transverse forms, usually five to seven in number. These sections usually are tested by drawing in some longitudinal curves, such as the sheer, and a few waterlines or level lines duplicating the so-called lift lines of a half-model. In addition, buttock and bow lines, longitudinal vertical sections parallel to the centerline of the hull, may be used. Diagonals, representing the batten curves over the molds, may be drawn in. In making the longitudinal drawing, the profile of the hull usually is drawn full size. Lofting is an important operation in boatbuilding, for it is the only way a design may be reproduced accurately or repeatedly. In the more advanced boatshops the structural details also are drawn full size, the lofting being done in minute detail.
Boats
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