Make a bracket to hold a piece of copper tubing on the transom. Make sure the tubing is behind the prop, so the prop wash will push water in to it. Also make certain the tubing is cut on a 45 degree angle. Wrap more copper tubing around the case of the engine. If you wish, you may also make/solder in brush cooling lines. Make an outlet somewhere on the body so that it is above the water level while the boat is not moving. Then use nitro fuel tubing to connect everything together.

Getting the water to shoot back far depends on how fast your boat is.

Ryan