A dry bilge may sound like a mythical creature that will never be encountered by mere mortals. With some careful planning, any bilge can be kept dry!
To keep a bilge dry, you need to keep water from getting in, and get the present water out. A sealed deck-hull junction will prevent water from coming in from above, as well as properly bedded deck hardware that does not leak; but what about the shaft? Shafts pass through a massive hole in the hull called a shaft log. To seal out water, the packing gland will press against the sides of the shaft, keeping water from dripping into your bilge.
The moment you begin to spin your propellers, friction will create heat which can cause serious problems in the packing gland. To negate this issue, the stuffing box is adjusted to allow a slow and steady drip of 1 to 2 drops per minute. This steady flow of water will lubricate the packing gland and cool the stuffing box. This dripping water will slowly fill the bilge, defeating one of the methods of keeping a bilge dry (keep water from getting in).
Here enters the second part of the equation, getting the water back out. Most stuffing boxes will drip water into the bilge, letting it accumulate until there is enough water for the bilge pump to extract. To keep the bilge dry, all you need to do is manage where the water goes from the stuffing box.
Instead of dripping into the bilge, set a pan or other collector under the stuffing box to accumulate the water without getting the bilge wet. This power boat used dog food dishes set under the stuffing boxes to collect the drips. A small hole was drilled in the top of the dish to secure a zip tie which holds a small hose in position inside the pan.
The hoses are led to a system of valves which act as a manifold. This system leads to a diaphragm pump which draws the water out of the shaft log pans in the stern and from the air conditioner in the bow. By turning on the pump and selectively opening the valves, each pan can be drained dry, thereby keeping the bilge dry as well.
