Posted: December 1, 2012
Inspect seacocks, hoses and stuffing boxes regularly.When the topic of sinking comes up, most sailors think of ferocious gales, uncharted reefs or fog-shrouded collisions at sea. The less- sensational truth is that more boats slip quietly beneath the water at their own dock than anywhere else. The majority of these sinkings involve failure of some type of hull fitting, which can include anything from through-hulls to stuffing boxes. Here are three common problem areas and what to look for when inspecting them.
Problem 1: Of seacocks, bad hoses and rusty clamps
All through-hull fittings below the heeled waterline of a vessel must be equipped with a seacock, which provides a means of preventing water entry into the hull in the event of the failure of a hose or another system component connected to the through-hull.
Industry standards for seacocks include marine-grade components (bronze or Marlon) and operation by a lever-type handle through a 90-degree arc, which gives a clear indication of whether the seacock is open or closed.
A majority of seacock problems involve the use of gate valves, which are not recommended for use on board (particularly below the waterline). In addition to improper materials (residential brass units, for example), a gate valve’s internal mechanisms are prone to corrosion-induced failures, and they give no visual indication of whether they’re open or closed. Worse still, the valve can fail to close completely due to trash or debris, allowing water to enter the vessel even after being “closed.”
Old, deteriorated hoses and corroded hose clamps are other possible seacock-related failures. Hoses should be supple with no signs of deterioration (e.g., cracks, splits), while hose clamps should be tight and free of corrosion. Installation of double hose clamps is also recommended if there is sufficient hose barb to allow it.
Solution: Conduct routine inspections of all seacocks, hoses and clamps. Exercise seacocks monthly to ensure proper operation, and only use marine-grade hoses and hose clamps.
Problem 2: Cracked composite through-hulls
A cracked through-hull located just above the waterline can reduce the effective freeboard of a vessel from feet to inches, meaning a boat only needs to settle slightly in the water before it begins to take on water and sink. Age and ultraviolet light damage are primary causes of composite through-hull failure; however, the stress caused by a bouncing, unsupported hose can cause cracking and damage as well. Cracks typically develop where the body of the through-hull joins the outside flange. In extreme cases, the flange will fall away completely, allowing the hose and through-hull body to fall inside the hull, leaving a gaping hole for water to enter.
Solution: Inspect composite through-hulls annually, at a minimum, for cracks and UV damage. If you find one fitting that’s bad, play it safe and replace the remaining ones, too, as they’re probably the same age and prone to failure.
Problem 3: Stuffing boxes and glands
Stuffing boxes for engine shafts and rudder packing glands are two more potential leak generators. Both are commonly located in difficult-to-reach areas, which means they often fail to receive the maintenance and care they deserve. Both are also common sources of slow leaks, which can go unnoticed for weeks or even months, until that day the boat mysteriously sinks.
Owners typically blame such sinkings on a weak battery or a faulty bilge pump, but in reality, neither will cause a boat to sink, although a constant, steady leak can.
Solution: Check stuffing boxes and packing glands regularly for leaks, deteriorated hoses and corroded hose clamps.
Finally, remember that the best defense in the battle to keep water outside your hull is a combination of routine maintenance and regular boat visits. Too often, boat owners rely on bilge pumps to keep a slow leak at bay; however, a bilge pump can also hide a leak until it’s too late. Installation of a bilge-pump counter will show excessive cycling, making leaks easier to notice and correct before disaster strikes.