If you increase the length 10%, you'll increase the volume by approximately 10%.

If you increase the length 10% and the width 10%, you'll increase the volume 21%. (110% x 110% = 121%)

If you increase all dimensions 10%, your volume will go up 33% (pretty significant).

Increasing length and width will also increase wetted surface, so you'll have more skin friction (drag) and will probably want those extra paddlers along!!

Shawn

: First, I'm no expert, so take what I say with reservation, and check with
: someone better educated in this field.
: Mill Creek is a pretty wide boat, lengthening should make it faster and
: easier to paddle.
: Loading 3 people will mean the boat should sink deeper (slow it back down,)
: and with less freeboard -- may need to highten the side panel --better
: check the loading capacity. However, since you lengthen the boat, the
: designer's original spec. may not apply (may be someone here can help you
: do the calcilation.)
: My 2 cents.
: Good Luck.