Shanna
An 18' High-Speed Aluminum Runabout
By William Atkin
A Useful Metal Boat
Iron, steel and aluminum, if used with good old-fashioned common sense, are excellent materials to use for building small boats of any type and especially ones of V bottom model. These metals are undoubtedly flexible and tough and if proper tools are available can be flanged, curved, cut, and shaped into frames, floor timbers, gussets, tabs, keel, plating, and butt straps with little more work than required for the building of a wooden hull. And for men accustomed to working in sheet metals a boat like Shanna will be a simple and straight-forward pastime.
Aluminum has the advantage over iron and steel in being light. It weighs approximately 170 pounds to the cubic foot which is a little less than three times the weight of a cubic foot of framing, planking and fastenings as generally used in the construction of wooden hulls. The tensile strength of rolled aluminum is 30,000 pounds and it has an elastic limit of 18,000 pounds, and so is not by any means a frail material. It may be interesting to add that rolled Tobin Bronze weighs in the neighborhood of 525 pounds to the cubic foot with a tensile strength of 90,000 pounds, while iron and steel approximate 480 pounds to the cubic foot, and respectively have 52,000 and 65,000 pounds tensile strength. Aluminum can easily be cut on a table or band saw fitted with metal-cutting blades and is rather easier to work than steel or iron. It is, however, very difficult to weld and therefore the fastenings in this wholesome little utility, Shanna, are aluminum rivets, screws and through bolts.
Shanna has an overall length of 18 feet; the waterline length is 17 feet 6 inches; the breadth, 6 feet; and the draft under the propeller, 1 foot 5 inches. The freeboard at the bow is 2 feet 5 1/2 inches; the least freeboard, 1 foot 8 1/4 inches; and the freeboard at the stern; 1 foot 11 inches. She is a very big boat despite modest dimensions. The arrangement shows a forward cockpit with wide single seat and lazy-back; the motor house is abaft this leaving a passageway on the starboard side of the cockpit; the opposite side is decked over to the coamings. There is a comfortable seat aft.
The lines show a V bottom model, rather sharp deadrise forward and flat at the stern. The chines are drawn together aft, reducing wetted surface as well as contributing to the seaworthiness of the little vessel. Shanna is designed for a speed of 35 miles an hour if powered with a six cylinder 224 cubic inch cylinder displacement motor of high-speed type and weighing not over 650 pounds.
Plans for Shanna are $50
Study Plans are available for $20
(Refunded when full plans are purchased)
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