I'm working on an idea in product development, though being still a fairly new student in this i still am left with a lot of questions, perhaps anyone can aswer? Say that i have a closed can with pressurised water lying in a pool of water. My question would be what the best method would be for this can to proppel itself forward using the pressurised water inside the can. Lets also not take into consideration such things as weight or flotation, consider that the height where thrust will be delivered is so near the surface that the pressure there is negligable. Would the best method of proppulsion be simply a waterjet? Or would it be better to convert to the movement of a screw?