Dimensions E68
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   Dimensions E 68

Dimensions E 68
... further background details



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Beam:
27 inch

A comfortable compromise between generous final stability and sufficient narrowness to promote a relaxed and efficient paddle stroke.

1 - Final stability refers to the ability of a hull to resist ultimate capsize. In general, beamier hulls will resist capsize more than narrower hulls. Pronounced flare of the hull (meaning that the beam of the boat increases from the water line up) will also promote greater final stability.

2 - However, the wider the hull, the further away from the paddler the paddle will be when in the water. The result is an inefficient stroke, which can tire the paddler and reduce the paddler's potential for speed.

back to Dimensions E68 -- Beam

 

Length:
16 foot 6 inch

1 - Its length gives the E68 the speed potential to keep up with any other single kayak out there. Also, the length of the E68 in relation to its displacement promotes efficient propulsion.

1 - Length, Speed, Efficiency of Propulsion

1.1 - Assertion:
For most touring applications hull lengths of 15 - 17 foot offer the best compromise of the three factors below. We need to weigh up making the boat longer to increase the potential hull speed and propulsion efficiency, and keeping it shorter, so as not to add undue drag.

1.2 - Factor - Wavelength:
A longer hull length at the boat's waterline (LWL), implies a greater distance between the bow wave and the wake (wave produced at the stern) at "hull speed". A longer wave length goes hand in hand with greater wave speed and thus, in this case, greater boat speed. Note: The overall hull length (LOA) is usually longer than the waterline hull length because of the overhangs at bow and stern.

1.3 - Factor - Wetted Surface:
A longer hull length also implies a greater amount of wetted hull area for a given displacement. A greater wetted area goes hand in hand with increased drag as a consequence of friction between the water and the hull.

1.4 - Factor - Area of Largest Submerged Cross Section:
For a given volume, the longer the object, the narrower and lower it will be. A longer boat of a given displacement will have a smaller cross sectional area immersed in the water than a shorter hull of the same displacement. Smaller cross sectional area, less water to push aside during forward motion. Less water to displace, less energy required to propel the boat, or: The boat will tend to move faster for a given energy input than a "fatter" one.

back to Dimensions E68 -- Length

2 - The length, combined with very moderate rocker, gives the E68 excellent tracking while on an even keel.

2 - Length and Tracking

2.1 - Assertions illustrated with a counter intuitive example:
A long hull with pronounced rocker may be easier to turn than a short hull with deeply emersed hull ends!

2.2 - Factor - Shape of Submerged Lateral Plane:
A longer hull is harder to turn than a shorter hull, because the further the forces opposing the turn (water besides bow and stern) are from the center of the desired rotation, the greater their leverage.

2.3 - Factor - Rocker:
The previous point assumes that the hull has a more or less constant draft over its entire length. If we reduce the draft nearer the bow and stern by allowing the keel to sweep upwards, we also reduce the area of the hull on which the water can act. Less area, less force, easier turning. This upsweep of the hull ends is called "rocker".

back to Dimensions E68 -- Length

3 - The E68 has a low enough initial stability to allow deliberate "edging" and thus provides great nimbleness in turns when required.

3 - Initial Stability and "Edging"

3.1 - Assertion:
"Edging" a hull, i.e. purposefully leaning it to one side or the other, changes the waterline foot print of the hull in plan view, as well as the amount of rocker of this new emersed hull shape in profile view. Both contribute to the hulls ability to turn even if it tracks like an arrow wile on an even keel! A lower initial stability promotes the ability to "edge" a particular boat.

3.2 - Factor - Initial Stability:
Initial stability refers to the ability of a hull shape to resist "heel" when starting from an even keel. Lower initial stability makes the boat feel tippier, but is an important feature required for seaworthiness and the ability to "edge" a boat. Initial stability is largely influenced by the hull's waterline beam and the cross sectional shape of the submerged portion of the hull.

3.3 - Factor - Tracking Vs. Nimbleness:
Good tracking comes at the expense of reduced nimbleness in turns, at least while the boat is on an even keel.

 

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