Stuffing boxes are an essential part of any boat (if you don’t have a sail drive). Positioned between the stern tube and the prop shaft, the stuffing box’s job is to stop water ingress while under power. Well, most of it anyway.
While a correctly adjusted stuffing box will only let in a small amount of water underway, a “dripless stuffing box” such as the ones made by PSS will eliminate water drips entirely.
These kinds of designs often come with a vent hose, which helps to ensure that air does not get trapped under the seal. The vent 
hose can occasionally vent out water, especially in hard reverse, so the usual method is to have the end terminate in a plastic bottle or similar receptacle.
While thrifty and practical, this isn’t the nicest looking install, so such setups are usually relegated to a lazarette or to the engine room, often perilously close to the waterline.
An alternative I discovered was to use a Float Air Hy-Vent, such as one made by Taco or Amtrol. These are often used on radiators and hot water heaters, and they will let air out but not water. So you can have your dripless seal properly vented, while any occasional rush of water will be blocked and won’t go all over the inside of your boat. They also look quite smart, and definitely a lot nicer than a plastic bottle.
All you need to do is screw a hose barb onto the bottom, mount it in a place that you find suitable, and away you go!
The best part? They are cheap (costing around $20) and can be easily found online or in hardware stores.
