Tech Wiki

Persistent Water in the Bilge

Q: Why is there so much water in the bilge after a rain?

This is becoming a very frequently asked question. However, it is not so simple a question to answer. For the keel stepped mast boats, there are a few more questions to be asked--fresh water? or salt? and in which compartments of the bilge? I have a dry bilge when the boat is in the water (Dripless Packing MAINSHEET May 92).

There are four compartments to the bilge. A small one (#1) just forward of the mast (with only 1 keel bolt); #2 just aft of the mast (with 1 pair of keel bolts); a large section #3 containing the manual bilge hose/electric bilge pump (2 pair of keel bolts); and an aft section #4 (with 2 keel bolts). On Apache, hull #788, there is a 1/2 to 5/8 inch drain hole from the forward bilge under the keel footing to compartment #2 and another drain hole (same size) to #3 compartment. Then a much larger hole (i.e., 3 inches) to accommodate bilge pump hoses between the aft two compartments. This larger hole is up from the bilge floor a few inches so any water will tend to accumulate. Rain water will wick down the spinnaker halyard into the halyard exit near the top of the mast and then into the center of the mast. This rain will exit the mast base and accumulate in compartments #1 and #2 and even overflow into #3 if there is a lot of rain. Thunderstorm type rain with high winds may only accumulate little to no rain. I've found the worst is a long steady drizzle. If you don't have a spinnaker, tape over the exit. Ralph Caruso [below] mentions my flap if you have a spinnaker halyard, but it's far from being perfected. Another source of rain water is obviously the mast boot, but in particular a poorly caulked mainsail track at the top of the mast boot. Water will empty into #2 and overflow into compartments #1 and #3.

No rain but fresh water in compartment #3? Check the starboard water tank outlet, cap and vent fittings. Fresh water in #4? Check hot water heater, all of the hose connections, under the sink as well as the shower sump and sink connections in the head compartment.

Salt water (again with dripless packing) only in compartment #4? Check packing gland, raw water hose intake/strainer in head, raw water connections at engine pump and heat exchanger, as well as all through hulls for leakage.

Salt water only in compartment #3? If you've been sailing on a port tack or a following sea, water will siphon from the separate electric bilge pump exit on the transom back into the bilge. I believe all the walk through transom boats have the electric bilge drain "T"ed into the manual drain which is high enough to prevent back siphoning. If this bothers you, install a one-way valve in the electric bilge pump hose. If I find salt water in only #1, #2, and possibly overflowing into #3, I look at the depth and knot log transducer fittings which are located under the forward settee.

The C34s with a deck stepped mast shouldn't have the rain water problem but make the appropriate checks if you find either fresh or salt water in the bilge. I have had one extraordinary storm that blew horizontal rain in from the stern. It blew water in through the slots and around the hatch boards. Fresh water was found in #4, but again that was extraordinary. I'm a firm believer in a dry bilge, if for no other reason than that it helps you find water leaks. If you are a believer in a dripping packing gland, I'd strongly recommend you purchase a counter (12 volt Radio Shack) and wire it to your electric bilge pump. Every time the pump cycles, it will register. An increase in the number of cycles in the same period of time will alert you to a leak. Also note the information in Winterization Tips

Ron Hill, Apache #788

  • In my 34' #247, I always had lots of water after a moderate rain. After 2 years of reseating most everything, I found that my fuel cap had never been caulked. I was and I still am amazed at how much water came in from that one source. If there is water in your head counter top after a rain, this would also explain that. In addition, if the prevailing winds are directly aft when it rains, a fair amount of water comes in the exhaust blower vents. I have also reseated the chain plates and one port. but the fuel cap was 90% of the water. I could never understand how 1" of rain water would put at least that much in the bilge. But the fuel cap was acting like a wick. David Aucella

  • Lately, when it has been raining, I've been checking the bilge and noticed that I have some water which is coming into the bilge at the bottom of the mast from the inside of the mast. I'm sure this is not water that is coming in around the boot, because I have taken a dry paper towel and run it along the outside of the mast to make sure that it was dry. I've been told by a local boat repair person that it is just rain that is blowing in through the holes where the halyards run through the mast.Do you know of any way of solving this so I can have a dry bilge, or if there is any retrofits offered by Catalina to cover the holes? Or, if it is something other than this?

  • I had a similar problem on my 1990 C34 Mast step. First the drain hole from the bilge in front of the mast step to the portion after the mast step (under the Mast Step) was not there. I had used a drill to "poke around until I found the hole that had been covered over during manufacturer with excess filler. I never thought much about it and filled the holes temporarily with Polysulfide caulk. Later I decided to remove the caulk and fill the holes (about 4 each 3/16" holes) with epoxy. When I drilled out the epoxy, I found a lot of water began coming out of the wooden mast step. I kept sopping up the bilge and letting it drain. I placed a heater aft of the mast and let it blow at 500 watts for about 24 hours and the drainage stopped. I then sealed the holes with West System thinking maybe the water came in from the bilge holes I had filled. I would bet the mast step is wet again, but currently I have the Mast pulled and plan on removing the metal Mast step bracket to gain access through the step top side. I will then drill out the bottom again and let it drain again. My thoughts were that I would drill out the current holes for the metal bracket with a over size bit or hole saw the fill them with West System including Colloidal Silica (406) or High Density filler (404) then re-tap holes for the lag screws to hold the metal bracket. Since I have the mast down I am looking at the top to figure out where the water enters the mast. On my mast the Signet Wind Instruments are mounted with a hole drilled in the top. It is not caulked so I will be filling it with polysulfide. There is a top plate on the mast so I can't see how water

can get in other than through this hole. Gerry Misener

  • Ron Hill had an idea to put a small rubber flap over the opening on the front of the mast where the spinnaker halyard exits. Evidently, it faces upward, and may be a major source of the water. The top of the mast itself has a cover. (I didn't know this till I went up and looked for myself.) Ralph Caruso

  • One source of water through the mast you may not have considered is condensation. I finally traced via process of elimination that as the most probable cause of periodic water coming from the mast of our '91C34. Down here in Texas we keep the boat in the water year round with heat on inside the boat during the winter. I finally figured it out after a norther blew through and pushed all the nice balmy moist air out of the area without making any rain, and I had lots of water exiting the mast. The mast offers an amazing total surface area if you condense water inside it over its full length and run it out a hole at the bottom. If it trickles out along the wiring bundle onto the cabin sole, it looks like a LOT of water. I had to make sure the wiring harness drips went into the bilge an not onto the sole. John Nixon

  • "Fine, but I'm still getting water in the bilge even if it's not raining and there's low humidity!" I hate to make this suggestion but have you tasted the water? It may be from your water system. If its from a tank fitting before the water pump you wouldn't have any pump cycling, although you'd be filling your tank more often than otherwise. Bob Greenhaus

  • I agree with Bob in that you should check your fresh water system. I had a small leak in my aft fresh water hose and it took me a while to track it down. Also, your hot water tank may be dripping water from the safety valve if it gets too hot when you are connected to shore power. All that being said here is how I tracked down the problem on my 34. I connected a "Y" valve at the shower sump and led a hose (under the sole) to the bilge. This allowed me to easily vacuum up the water that the bilge pump would leave behind. Now, with a dry bilge this allowed me to closely study where the water was coming from. If you are getting 2 to 3 inches in 24 hours you should be able to find it quickly. I had a leak at the rudder tube that I glassed over and the stuffing box needed adjustment. Now by bilge is dry as a bone. To keep it that way I blocked up the drain hole in the aft horizontal stringer. Now water that leaks from the stuffing box collects there, it's easy for me to vacuum up with my shower sump pump. There was a time when I thought a dry bilge was impossible, but once you dry it out it will be easy to find the culprit. Note: you must had dry the bilge after vacuuming. It take forever for the water to evaporate in the bilge (David Aucella). I used a Y-valve to T into the fresh water line just before the 12 V pump so I could get water from a foot pump in case of a failure. I purchased the garden hose Y-valve, barbed fittings and hose at West Marine. I'm sure that this same Y would work in the shower sump line. Another thought would be to T into the raw water intake for the engine cooling. This could have a two-fold purpose. First, it would be easy to rewinterize after a winter sail and secondly could also act as a backup bilge pump in case you ran into a big BIG leak. The Y-valves and fittings I'm talking about are for 1/2 to 3/4 inch hose. Ron Hill, Apache #788