: Are you aware of "Kayak Foundry", the kayak designing
: program available free from the blueheron site?

: http://www.blueheronkayaks.com/kayak/index.html

: I just used it to confirm what I suspected would be the effect of
: what you are describing. If you simply lower the sheerline at
: the bow and stern, but keep the plan view the same shape, then
: apart from the loss of volume, there is a tiny change in the
: waterline shape. There is less height for the bit just behind
: the bow to reach out to the width at the sheerline, so it flares
: out a bit more and the waterline shape changes very slightly.

: The effect on the drag and stability and the trim are almost
: imperceptible if the bow and stern are dropped about an inch. On
: the design I was playing with, the drag increased at 4.5 knots
: by about half of one percent. That is probably because the
: waterline has a very slightly less fine angle of entry. You
: would not notice a change as small as that.

: Changing just the bow moves the centre of buoyancy, but only by
: 1/10th inch, so you wouldn't notice that either. Changing the
: stern as well brings it back more or less to where it started.

: You could compensate for that by reshaping the first form, but I
: think the difference would be less than the amount you would
: sand off the strips to get the hull smooth.

: My impression, which playing with a design confirms, is that if you
: are only thinking of dropping the bow by an inch, then you would
: not notice any difference in the behavior of the kayak and it
: probably would not create an uneven curve. Any more than an inch
: and you might need to check as you fit the strips that you still
: have a smooth curve.

: So my instinct and my experiment with "Kayak Foundry"
: suggests that the effect of the change you are describing would
: probably be significantly less than the effect of your leaning
: slightly forward or back as you paddle.

This is one of the problems concerning computer based design, it doesn't tell you the whole picture. In flat water, what you said is true, but if you're dealing with rough water, the volume lost above the waterline is significant, something the computer program doesn't deal with.

Bill H.