Board Boats
A board boat is basically a boat that is mostly a large air box with a small foot well instead of a cockpit.
You sit on the top sides of the boat, and there is nothing between your rear end and the water.
Also known as a "wet pants" class boat.
Simple Board Boat
This is the easiest way to make a pdracer board boat, combined with plank construction technique, you could make this boat in no time.
It has 2 bulkheads that form the fore and of the foot well, and side decks protect the sides from having water come over from the gunnel.
Add a spray rail to the deck or just forward of the foot well to deflect spray that has landed on the deck.
You can make the foot well self draining by adding a false floor with drain holes to the side.
Sides to the foot well can be added, making the well even smaller so in the event of a swamping, you will be carrying less water.
Donut
This is a simple board boat with a long foot well.
The floatation boxes built on the entire perimeter of the hull, sort of like a big donut.
The extra length to the foot well is nice to have for storing gear such as oars, umbrellas, water & snacks.
Also makes it easier to take a passenger.
The cockpit is just long enough, that if a tent was added to the top, could anchor out and sleep in there.
Later a removable deck was added to the forward end of the cockpit, this is to deflect spray & breaking waves that came over the bow.
With the foot well completely filled with water, it is still sails rather nicely.
Heel the boat over a bit to dump some of the water out, and bail the rest.
2 Level Draining Cockpit
Mike Falasca drew up this concept, it is a 2 level self draining cockpit.
You can sit in the middle looking forward while sailing.
Possibly add a set of foot steering gear, and a reclining seat.
Open Ended Self Drain Cockpit
There are many racing sailboats that have an open ended cockpit.
If the boat does a nose dive into a wave, all the water runs over the top of the boat and out the stern.
You could build it either as an open ended cockpit, or have a pair of drains in the corners of the stern.
With a long cockpit, you can have a 2nd passenger, or have enough space to row with a set of oars.
Hump Bow
This is an unusual looking compromise to create a hull with the least amount of freeboard (and wind resistance), yet has a large enough bow transom to keep from digging the bow.
She could be built like a shoebox, or with a self draining cockpit for the quickest knock down recovery speed, so you can quickly get back to a race.
Q&D PD
John Wright built a super simple board boat that is very radical looking.
The most noticable thing is the sides have been extended down to make bilge keels.
The cockpit was made in a very simple manner, it is attached to the forward bulkhead and stern transom, the curvature of the cockpit gives it strength.
There are no frames or support between the bottom and the cockpit, just the curvature.
PD Skiff
Here is an extreme version of what a PD could be.
All carbon fiber construction, open ended transom with self draining cockpit, 16' mast with fully battened main sail, jib, and enormous asymetrical spinnaker.
And that open transom will be really easy to reboard after you continually ditch her, because of the super over sized rig.
Simple Board Boat
Donut
2 Level Draining Cockpit
Open Ended Self Drain Cockpit 
Hump Bow
Q&D PD
PD Skiff