Trying to solve a bilge water puzzle

[bsangs]

After a mostly uneventful summer of sailing, I've come across an aggravating development. (I will post photos of this later, as I haven't taken any good ones yet.)

I always make sure the bilge is dry before we head out, and have no problem doing the taste test. For instance, I realize the fresh water is present after it rains, due to the mast, and I know the small amount of brackish water I get in the most aft part of the bilge is due to that tiny dust bin keel bolt leaking. However, after the last couple sails - which have involved quite a bit of motoring for lack of wind - we've come back to find about an inch of the brackish water in the four main bilge compartments, and I've no idea why. The water does not have any diesel/oil taste or color to it, just the usual Hudson River look and taste.

There is no visible water trail from rear of the bilge, from the sides, or from the front. The galley seacocks and hoses are not leaking, and that area is dry. Under the engine is damp, but when I look at the shaft it appears bone dry. I see some visible rusty looking water marks to the rear of the shaft, under the exchanger, but it doesn't appear to be much. It's as if this water is coming into the bilge from below. I've yet to go completely down into the engine area from behind, but realize that's the next step. If we're lucky enough to get out again before having everything winterized, I plan to go down below and watch what happens while my wife takes the helm. (The wife that says, "Stop obsessing. It's a boat bilge. They get water in them." )

I've read countless bilge posts on these forums, but am still stumped. Any advice or suggestions from the longtime Ericson owners? Thanks in advance.

 

[Loren Beach]

There are several threads here about water coming in around the top of the short rudder stuffing box fitting. Only under power at a good speed or under sail at hull-speed. Might be worth a look, albeit a somewhat difficult place to observe while under way, in some models.

 

[bsangs]

There are several threads here about water coming in around the top of the short rudder stuffing box fitting. Only under power at a good speed or under sail at hull-speed. Might be worth a look, albeit a somewhat difficult place to observe while under way, in some models.

That was going to be my first place looking if/when we get back out. (Yes, it won't be an easy observation place on my 35-3.) And that water would flow below the primary bilge entryways? Thanks for the confirmation Loren.

 

[Kenneth K]

It's as if this water is coming into the bilge from below.

Yeah, the bilges can fill from either above (mast water, spills, deck & window leaks, pressurized plumbing leaks) or below (anything that perforates the hull).

Since you said you had water in four bilge compartments, I'm guessing your bilges have the limber (drain) holes at the bottom like this:

Some boats (apparently some 38s) have caps that can seal off the limber holes in each bilge section--but I can't understand why.

Most of my understanding comes from the 32-3, but I think the 35-3 is pretty similar. Generally (with a few exceptions), wherever there is a hull perforation (a thru-hull, the rudder tube, prop shaft log, or a transducer) the TAFG is cutaway around the perforation. This means any leakage from the perforation drains inside the cut-out, under the TAFG, along the hull bottom, and, when enough water collects, into the bilge limber holes to fill the bilges from below.

There are at least 5 cutouts aft/abeam of the engine: Two (port and stbd) around the stern thru-hulls, a long oval cutout around the rudder tube, a large rectangular cutout around the prop stuffing box/PSS, and one around the galley thru-hulls. Leaks from any of these areas will cause a water-rising-from-below situation in the bilges.

The depth transducer (at least mine, which was factory installed) is installed in one of the TAFG tabbing areas where the TAFG is bonded to the hull. A large limber hole in the base of the TAFG means any leakage here is also kept below the TAFG:


The speed transducer is also in a TAFG cutout area near the bow.

The big exception to the TAFG cutaway scheme (at least in the 32-2) is in the head. Here, the lowest point of the plumbing area under the sink happens to be the cabin sole, as the molded TAFG rises higher than the sole to accommodate the shower floor. So leaks from under the sink area (including the thru hulls) wind up on top the wooden sole and have to spill into the bilges from above.


However, the 35 head/shower setup is very different than the 32, so this may not be true for your boat.

 

[bsangs]

Yes Ken, I have the limber holes like that in the bilge, five in total I believe. Thanks for all those details. While I'm certain the water isn't coming from the galley or transducer cutout - which is located below a platform in the v-berth - I'll be sure to check all those areas thoroughly.

 

[Christian Williams]

Observe the rudder tube packing gland (where the post exits the tube) while under full power (which makes the stern squat). Water may pour in only in that circumstance.

Full discussion here.

 

[Bepi]

Check your exhaust hull fitting bedding which, depending on the vessel, could occasionally be under water in waves or when heeled over. One more possible source.

 

[bsangs]

Observe the rudder tube packing gland (where the post exits the tube) while under full power (which makes the stern squat). Water may pour in only in that circumstance.

Full discussion here.

Yours was the post that put greasing the tube atop my list of "easy" solutions. I might do it regardless, since it's likely never been done. When we're out next, I'm going to camp down there and watch what happens. Will leave a note as suggested.

 

[bsangs]

Check your exhaust hull fitting bedding which, depending on the vessel, could occasionally be under water in waves or when heeled over. One more possible source.

Oh the exhaust is definitely under water at times when I'm underway. Can hear the gurgling when it occurs. You saying water might be leaking around the thru hull if the bedding is bad, and filling the bilge, or that water could be coming into the actual exhaust?

 

[Nick J]

Oh the exhaust is definitely under water at times when I'm underway. Can hear the gurgling when it occurs. You saying water might be leaking around the thru hull if the bedding is bad, and filling the bilge, or that water could be coming into the actual exhaust?

not specifically related to the exhaust being under water, but this post reminded me of what I found on my exhaust system before replacing it. This is a picture of the original 90 that's connected to the thru hull. I can't remember what the smaller tube was originally used for. On my boat the rubber hose was capped and secured to the side of the starboard cockpit locker:

I didn't whiteness it leaking, but I imagine this could have put a decent amount of water in the bilge while using the engine.

 

[Bepi]

Oh the exhaust is definitely under water at times when I'm underway. Can hear the gurgling when it occurs. You saying water might be leaking around the thru hull if the bedding is bad, and filling the bilge, or that water could be coming into the actual exhaust?

When you start your engine and you look over the side to ensure that water is spitting out, that fitting.

 

[Loren Beach]

not specifically related to the exhaust being under water, but this post reminded me of what I found on my exhaust system before replacing it. This is a picture of the original 90 that's connected to the thru hull. I can't remember what the smaller tube was originally used for. On my boat the rubber hose was capped and secured to the side of the starboard cockpit locker:
View attachment 44821
I didn't whiteness it leaking, but I imagine this could have put a decent amount of water in the bilge while using the engine.

That connection to the outlet fitting for your wet exhaust is for the vent hose from the top of the water feed line that goes into your exhaust elbow.
it carries a small stream of water while the engine is running, and admits air to prevent a syphon from forming in that loop back the engine when the engine is shut down. Universal used to put this on all installations but I know mechanics that say that most boats do not benefit from it. My new Betamarine did not have this as standard but there was note in the install manual that such a hose might be a good precaution in some installations, I did not choose to do it. My mechanic said I did not need it for our particular boat.

 

[Christian Williams]

For the record:

My installation uses another option, which is to put an anti-siphon valve in the hose from the heat exchanger to the exhaust elbow.

That makes a vented anti-siphon loop out of that hose. However, to work when the boat is heeled over, the loop has to extend quite high, to cockpit level. On the 381 there's room for that in a space between cabin house and outside bulkheads.