You will need to roll out a slab with either a slab roller, set to about 1/4" thickness, or using two sticks as guides.

You will need to learn how to roll a slab, or two.

Then you will make a template for the sides of the boat. Cut out both sides, and then score and slip, and smooth together. Add a bottom if  you need to, but make sure your boat can stand on its own.

Once you have the basic form, you can add on and carve away to make your own fantasy vessel!