Pennies...unless your pumpkins are the size of dimes.
it can hold 50 pennies depending on the base of the boat and also depenidng on the sides now if you have a 20 by 20 then may be a 100 or 150 pennies it may hold
Heads.This is beause it has less of those carvings on it than the tails side,which allows more room for the water drops.
It depends on which has more surface area.. and more volume to displace water.
Make the surface area as big as possible. You can just fold the edges up so it looks like a square plate with its edges folded up.