BOAT DESIGN TERMS
Differential Bow and Stern Profiles: Asymmetry and differential rocker encourages different bow and stern profiles, or curvature, when viewed from the side. Increasing bow profile radius improves maneuverability, reduces wetted surface and drag, reduces impact damage, and encourages the bow to shed floating debris, like seaweed. Tightening the stern profile improves tracking and handling in following seas.
Differential Shear: Our shear line — the arc formed by the gunwale from bow to stern as viewed from the side — is lower in the stern to reduce weight and wind purchase. We use roughly half as much rise to stern as to bow. Differential sheer also aesthetically balances our larger bow profile.
Elliptical Bottom: Elliptical Center Sections increase initial stability and give more predictable handling when combined with soft chines. Elliptical bottoms are harder to stiffen than arched bottoms, but we take care of that. Soft Chines improve “sea kindliness” as the canoe tips less in beam seas – when sideways to waves.
Flare: Placid Boatworks canoes are flared from bow to stern. The sides of the canoe widen increasingly from the waterline upward for most of the vertical distance to the rail. That flare directs waves upwards and outwards, keeping our canoes very dry in waves and spray. Flare also increases final stability by increasing the volume of the boat in the water as it is heeled or rolls to either side.
Gothic Arc End Sections: Arched end sections increase flare above waterline and yield fine entry lines. In the stern, these combine to improve tracking, and make the boat more kindly in following seas. In the bow, we modify the arch by rounding the profile (under the keel line) to reduce drag, quiet the hull, and reduce front impact damage.
Moderate Asymmetry — placing the widest center section aft of amidships — increases forward performance and narrows the bow station in tandems. Asymmetry compromises reverse maneuvers and back paddling. Our Fire boats are play boats and moving water trippers, and have little asymmetry. Our flatwater trippers have moderate asymmetry and our ultra cruisers have more radical asymmetry.
Rocker: Rocker is upward curvature along the keel line at bow and stern as measured from keel at boat center. Increased rocker increases maneuverability, reduces trim sensitivity and decreases wetted surface. Increasing the rocker in the bow relative to the stern increases the bow paddlers control of the canoe and quiets the bow wake without compromising tracking. The stern has less rocker to aid in keeping the canoe on course and to stabilize the boat in following seas. This is particularly important in double-blade paddle pack canoes, as horizontal, sweeping forward strokes are often used.
Shoulders: Using a complex SHOULDER, Placid carries flare high to a double radius that tumbles home to efficient narrow rails. The tight radius deflects waves outward and the TRIANGLE of RESERVE indicates how shoulders increase reserve stability.
Tumblehome: A carryover from wooden canoes where the bilge curvature of bent ribs carries the ends upward and inward. The shape necessary in traditional canoes narrows gunwale spacing, providing narrow paddling stations. It is easier for smaller paddlers to get both hands across the rail for more efficient strokes. Narrow gunwales also ease portaging because the hands are closer together.