: Hi i would like to know ,how to make my forms from my great auk kayak in to a
: double person kayak? I would also like to know how short in lenght i can
: make the guillemont double? It will still be for to people. thank you marc

Rub-a-dub-dub three men in a tub . . .

Marc,

The prime factor in determining the length of a double is how closely you can pack the paddlers.

You need adequate leg room for the front paddler. That gives you a minimum distance to the bow of the boat from the front cockpit.

If the boat is very wide the rear paddlers feet can come along side the front paddler. This is not particularly comfortable, but you'll occasionally see it with a parent and small child paddling in a single which has a large cockpit. With two adults you would probably want to allow decent legroom between the two paddlers.

Legroom, though, onle sets a bare minimum. Depending on paddling style you may need to increase he distance between paddlers so their paddles do not hit each other. If you like using a long skinny paddle, then you should be further from your partner, or else be very good at paddling in synchronization.

From this geometry you can define the center of the boat. You add a nose and a tail to give you the bouyancy and speed characteristics you want. A short wide nose for maneuverability or a long, pointed nose for a sharp entry angle for greater speed. The tail would be shaped for streamlining, bouyancy, and control. A tail that looks like a rudder will act like one, and give you a boat that tracks nicely. A stubby tail will make the back of the boat look like a bathtub, (or a rubber liferaft) but you'll be able to turn easily.

Depending on the weight of the paddlers the width might need to be increased to give added capacity, or the side height might need to be increased, but these would be minor tweeks. For most doubles the capacity (or displacement) is already great enough to stay afloat with two paddlers -- and then some.

The length you decide to make your boat is fairly flexible, but I hope some of these thoughts help you decide what you will be doing.

Do you have a limit on a size for storage or transit? Is there a weight concern?
I ask because I am wondering why are you thinking of shortening an existing design. I know there must be some reason, and perhaps if we knew that we could be more specific in answering your question.

PGJ