Physics of Self Bailing Boats and How I Built One :: physics boat boating ship

The Basic Principle behind a Self Bailing Boat Actually the idea is quite simple really, it consists of a floor above the hull with open drain plugs in the rear of the boat and above the water line. By this simple method as water comes in to the boat it will drain right out of the back. If too much weight is in the boat then water will simply come in through the drain holes. This is no worry to me because I can always just put some plugs in the drain holes when carrying a heavy load. I made the decision to build the aluminum skiff 17ft long and strong enough to hold an outboard motor with a mass of 141kg (approx. mass of 90Hp Mercury). My Boat Dimensions I made the decision to build the aluminum skiff 17ft long and strong enough to hold an outboard motor with a mass of 141kg (approx. mass of 90Hp Mercury). Knowing the amount of material I would need; I then went on to estimate the mass of the boat when finished to be 239kg. I also made the decision to build a fuel tank in the front of the boat holding 141kg of gasoline (≈ 38gal). The design of the boat permits the boat bottom to have an estimated area of submersion of 5.55m2 (L= 3.7m W=1.5m). With these measurements in hand I knew I needed a way to determine the height from the bottom of the boat at which I should build my second deck and drain plugs. I got a value from a veteran boat builder but surely there was an equation to help me out. Archimedes’s Principle for Floating Objects: So hears the theory: Archimedes principle says that the magnitude of the buoyant force always equals the weight of the fluid displaced by the object. This buoyant force always acts upward through the point that was the center of gravity of the displaced fluid. In the case of floating objects the buoyant force is equal to the force of gravity on the object. Knowing that the change in pressure is equal to the Buoyant force per unit area (ΔP = B/A) we see that B = (ΔP)A and ΔP = Ï gH where Ï  is the density of the fluid g is the acceleration due to gravity and H is the height of the fluid displaced.