You will be able to use 3D Boat Design for finding the drag or resistance.
There are two options: (most likely look at the Kaper option)
Kaper and Michlet
Kaper uses static values, waterline lenght cp etc. But when the kayak actually moves in the water, the waves can change waterline.
The michlet method calculates the “total (viscous + wave) resistance and far-field wave elevations of thin monohulls and multihulls”. The “average” speed of these ships might be somewhat higher and the method a little less accurate at lower speeds.
I am no expert, so I am sure other places will have some good input for you. Any proper boat building book should also explain the process.