Thread: project!

Hi! im making a project and i know nothing about boats! please help me!
we have to built a boat on any material. It has to carry a 1 litre bottle of coke fill up with water, in any part of the boat, but vertically. It has to advance 5 metres in a tank of water 40cm of width, a bit more than 5 metres of lenght. The boat has to be only moved by a jet of water that hits it 10 cm on top of the flotation line, with a deviation of 3 cm (7 to 13). The jet of water comes from a tank filled up with 15 litres of water, and its free surface is at 2 metres from the ground, while the tank that contains the boat has its free surface at 40 cm from the ground. We don't know how the jet is going to be (its force and how much it will last), the teacher is still deciding it.
We need the design of a quick and stable boat, and we were thinking of doing it in plumavit. We know it has to be thin and long, but we dont know how thin and long.
Also, we thought of making the bow/prow (that is where the jet will hit it) concave, because we think less of the energy given by the jet will be wasted, but we are not sure of this either!
PLEASEE HELP!