Few things are more satisfying than lifting your floorboards and seeing a sparkling clean bilge free of crumbs, dust, and water. Unfortunately, this sight doesn’t last too long after delivery of a new sailboat. While some boaters meticulously clean their bilge, most don’t and only put eyes on it when they check for water ahead of their sail.
Water will naturally accumulate in the bottom of the bilge as it’s the lowest point in the boat. Water can and will enter the boat for several reasons including a leaky deck hatch, cleaning of transducers, freshwater plumbing leaks, weeping thru-hulls, raw water colling system leaks, condensation from an air conditioning system, and even from the ice box drain just to name a few. For starters, a small amount of water in the bilge is not a huge concern but a more significant amount of water needs to be addressed and more importantly, the source of the water confirmed.
The first action taken (assuming the boat is not sinking) when discovering a significant amount of water in the bilge is to identify if it’s saltwater or freshwater and the only reliable method is to taste it by dipping your finger in the water.
Assuming the taste test has identified freshwater, breathe a sigh of relief as freshwater leaks won’t sink the boat in normal settings. Freshwater leaks can come from within the boat’s plumbing system or from outside via rain or a hose. To identify a plumbing leak, one should start by turning on the freshwater pump and monitor for a few minutes listening for the pump to go on and off. If this is happening it means the system is losing pressure, but if the pump is staying off (after initially building pressure) it means the leak is likely coming from outside. If the water pressure test shows no signs, the leak is likely coming from outside due to a bad hatch seal, leaking deck fittings, blocked drains, etc. The water pressure test is not 100% accurate as freshwater leaks can come from outside the pressurized plumbing but it will eliminate a large portion of possibilities. For example, a water tank with a crack or leak in it would not affect the pressure system.
But what if it’s saltwater? While saltwater ingress is more urgent, these types of leaks are easy to find as water can only come in from a few places assuming the boat hasn’t hit anything, or the sea state is calm meaning the boat is not taking waves over the bow. Possible locations of a saltwater leak include the rudder tube, prop shaft, thru-hulls, raw water pump and associated components (we see this the most), and keel bolts. Boats with saltwater washdown pumps for the anchor locker or cockpit can add these to the potential leak. A steady leak from one of these examples will be obvious with pooling water around the area or corrosion on metal surfaces. Saltwater leaks usually start slow and deteriorate over time but unfortunately most issues require the boat be hauled out in order to make proper repairs.
So long story short… you should always check you bilge and bilge pump operation ahead of any boating, but a small amount of water is somewhat normal. Larger collections of water should be identified, monitored, and repaired based on the findings.