to Ralph Hoehn at:
Please tell us your name, your phone number and a good
time for us to call you back after 7:30 pm EST or on weekends.
(We do check messages constantly!)
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.
to Dimensions E68 -- Beam
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
1 - Length, Speed, Efficiency
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.
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
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".
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
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.
Good tracking comes at the expense of reduced nimbleness in turns,
at least while the boat is on an even keel.