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Unknown source of seawater ingress 2004 Catalina 350

Sep 27, 2018
1
Catalina 350 Victoria
Help!
IN the past month I started to detect a small amount of sea water ingress (1/2 cup per day) in the bilge (transducer access hatch in forward cabin) and I can't determine the source. The boat is alongside, has not grounded or struck anything, there is no leakage through any through hull fitting or through the transducer/log area which could have contributed due to the relative height and forward position of this part of the bilge. I've run my hand as far forward through the deck hatch as I can and the decking is slightly moist (not soaking), but I can't find the source which slowly accumulates before dripping into the "lower bilge" (where the keel bolts and bilge pump are located). There is no obvious ingress from any deck fittings, from the fresh water tank (under the forward berth) or from condensation. The water is clear and and tastes like undiluted sea water. To see if it is fresh water, I've cleaned and dried the entire bilge surface with fresh water to see if the water might have been mixing/diluting with dried salt water residue on the inside of the hull, but it still tastes salty.

Any ideas where the water is coming from? Could it be a fresh water leak but the dilution is taking forever??
 
Oct 22, 2014
15,874
CAL 35 Cruiser moored EVERETT WA
If it is salt water you either have sprinkled salt in the water or it is sea water that has entered the boat. It happens when you have a leak in the hull. You get water over the bow (going through waves), or you bury the rail and there is a deck leak.
My first area to test is all of the thru hulls. Clean and dry the areas around all of the thru hull. When dry sprinkle a little flour lightly around each of them. Just a little you need to clean it up... Give it a little time then check. you should see a trail in the flour when the leak is. Tighten the clamps or replace the hose and install new clamps.
Cleanup with a vacuum using a good HEPA filter.

If that does not solve the problem then you are looking for a lean elsewhere. The same trick works. You know where the water is, you want to know where it is coming from. Sprinkle the flour in the dry location where the water shows up. You should see the water trail enter the area. Follow the trail toward the leak.

No magic just a detective job that can be frustrating.
 
Mar 6, 2008
682
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
I found that the seal in the windlass was letting water in. This water also makes the very front of the vberth mattress wet. You can test this by exposing the windlass motor from below and have someone spray water onto the windlass from above. You can cover the windlass with canvas untill you can fix the leak.
 
Jun 8, 2004
2,555
Catalina 320 Dana Point
Check the anchor well, they frequently ship water thru the drain as you hit waves and any leaks in the drain or bottom of the anchor well would be in the area you describe.
 
May 20, 2016
2,992
Catalina 36 MK1 94 Everett, WA
My guess is the anchor locker drain thru hull fitting. These have been known to fail.
 
Jul 1, 2010
861
Seaward 25, Catalina 350 Erie, Pa
As already mentioned above, check the windlass. I just had to replace the shaft seal on mine this summer. On our boat (also a 350) the water dripped down on the shelf at the bow and also got the mattress wet some. Depending on the cover under the windlass, it might also run down inside the hull without showing up on the mattress. Of course, you'd have to be hitting some waves or anchoring out to get seawater up that high. Ours was from some nasty thunderstorms and heavy rain.

Also, could it be coming in the head intake thu hull area or hose fittings and be running toward the area you're finding the water in?
 
Last edited:

Strgzr

.
Oct 9, 2014
3
none none none
Help!
IN the past month I started to detect a small amount of sea water ingress (1/2 cup per day) in the bilge (transducer access hatch in forward cabin) and I can't determine the source. The boat is alongside, has not grounded or struck anything, there is no leakage through any through hull fitting or through the transducer/log area which could have contributed due to the relative height and forward position of this part of the bilge. I've run my hand as far forward through the deck hatch as I can and the decking is slightly moist (not soaking), but I can't find the source which slowly accumulates before dripping into the "lower bilge" (where the keel bolts and bilge pump are located). There is no obvious ingress from any deck fittings, from the fresh water tank (under the forward berth) or from condensation. The water is clear and and tastes like undiluted sea water. To see if it is fresh water, I've cleaned and dried the entire bilge surface with fresh water to see if the water might have been mixing/diluting with dried salt water residue on the inside of the hull, but it still tastes salty.

Any ideas where the water is coming from? Could it be a fresh water leak but the dilution is taking forever??
Simple problem to fix. Between the Bow sprits, take a large tub of rubber silicon and fill in the inverted V facing the bow sprit from the font of the boat. Water enters through this area. I used a credit card to shape the silicon artfully. The Tang is located there too. This cured my water issue which traveled under the chain locker, through the forward storage area, under the forward water tank, and into the area for the forward thru hulls. Also, note, there is a cone inside the base of the mast that sticks up. If the weep holes in the base of the mast aren't flushed out regularly, especially with in mast furling, the water will overwhelm that little stand up tube for which wires go through, and under the head sink. I also used old medal windshield wiper blade pieces, move it in and out of the weep holes to ensure the mast can drain adequately.
 
Last edited:
Jan 18, 2016
667
Catalina 387 Dana Point
Silicon belongs on the chips in the electronics. Silicone sealer belongs nowhere on a boat, as it can never be successfully removed and resealed (nothing will ever stick there again).

Use a polysulfide or polyurethane caulk to seal boatstuff.

The flour suggestion is a good one. I'll also drop paper towels around to see which ones get wet. IMHO, You need to track down to the real source before you break out the tube of 5200.

I'd immediately suspect a weeping transducer mount or through the transducer itself. This would get very high on my list if you cannot find anywhere water is getting into that compartment.
 

Strgzr

.
Oct 9, 2014
3
none none none
Silicon belongs on the chips in the electronics. Silicone sealer belongs nowhere on a boat, as it can never be successfully removed and resealed (nothing will ever stick there again).

Use a polysulfide or polyurethane caulk to seal boatstuff.

The flour suggestion is a good one. I'll also drop paper towels around to see which ones get wet. IMHO, You need to track down to the real source before you break out the tube of 5200.

I'd immediately suspect a weeping transducer mount or through the transducer itself. This would get very high on my list if you cannot find anywhere water is getting into that compartment.
Generally I agree with the silicon belonging nowhere on a boat, however in this case it is on stainless between the bow sprits around the tang. He indicated the water was coming aft and puddling in the area of the transducer after traveling through the most forward bilge holes. It then moves from there to the forward keel boat area under the sink. And if that fills, it will move aft. So, this was the real source of my leak that perplexed me for quite some time. V area between the bow sprits was the issue and I suspect it is fresh water. Filling that V-area cured it for me.
 
Jan 18, 2016
667
Catalina 387 Dana Point
And I'd say that 4000UV would have worked better, with a far more tenacious hold. (but still removable, mechanically and chemically)

Advice for the OP still stands, keep looking until you find the source. The taste test indicates salt, so not likely wash or rain.