2001 340 Sundancer Transom Leak Conundrum

bfernald0

bfernald0

Well-Known Member
May 18, 2020
411
Marina del Rey, California
Boat Info
340 Sundancer 2001
Engines
8.2L Mercruiser ECT Horizons
Looking for anyone that has experienced this issue.

I've included a link to three photos below and a video. Long story short, on the interior of the transom right to the outside of each stringer, I've got a small hole that weeps water. It's about the same spot on both sides. I've had the boat hauled twice now. Removed, re-glassed and then reinstalled, rebedded the trim tabs and actuators, the transom sonar, the zinc plate, etc. All to no avail.

On a cruise over the weekend, following the last haul out, I filled the bilge with freshwater as a result of a yard worker knocking the water heater connection loose.

If you look at the video, you will see bubbles rising from one of those holes on the port side. I initially thought the boat was sinking. However, after tasting the water and checking the water tank level, I realized it was a freshwater leak. So where are the bubbles coming from?? The answer is exhaust. When I turned off the port engine, the bubbles stopped. Turned it back on and the bubbles started.

Best I can figure, one or more of the screws holding on the underwater exhaust ports is leaking into the fiberglass. The water, of course, runs downhill toward the transom and weeps out of the two areas. When the engines are running, the water is replaced by exhaust gas.

I'm moving toward a THIRD haul out to remove the exhaust ports, grind, glass and rebed them.

Before I do that, however, has ANYONE had a similar problem? This has been a 2 year trek to get a dry bilge and figure out where this water is coming from. I feel like this freshwater leak was a fortuitous event, as I would never have seen the exhaust bubbles.

https://www.amazon.com/photos/shared/ynP5-FwtS3yqt0hrIxC3Ow.hSSff20SUwKoHozRRtNNsA

Thanks

B
 
That is very strange. My 97 330 has the same hull as your 2001 340 and I have no similar issues. What is strange is that the bronze exhaust ports exit straight below where your exhaust pipe is, and not inside a stringer, but its the stringer that seems to be where the bubbles are coming from. I guess pulling those exhaust ports will help determine what is going on and whether there is some kind of structural damage or delamination in the hull under the ports. By chance do you know if the boat was grounded or hit something? Your engines are not original. Were there any other changes to the hull in the process of that installation?
 
bfernald0 said:
Not aware of any groundings and no modifications to the hull or exhaust ports were made when the new engines were installed.
Click to expand...
So sorry to hear of this. Keep us posted. I’ll ask around our harbor and let you know if I hear anything. You sure don’t want water getting into the stringers.
 
Spoke to SeaRay. They said that the exhaust tubes are tied directly into the hull and that it sounds like there's a void or crack on the inside of the tubes. Boat is being hauled again in the morning. We shall see...
 
bfernald0 said:
Spoke to SeaRay. They said that the exhaust tubes are tied directly into the hull and that it sounds like there's a void or crack on the inside of the tubes. Boat is being hauled again in the morning. We shall see...
Click to expand...
Good luck and keep us posted.
 
Very interesting findings. Pulled the boat (3d time) and removed the exhaust ports and sanded off the bottom paint and gelcoat. After an hour or so we observed water seeping out between the exhaust tubes and the hull. As you can see, Sea Ray used prefab 6 inch fiberglass tubes and glassed them in flush with the hull. It appears that over time, the exhaust pressure, vibration, etc. forced water between the outside of the tube and the hull. It ended up working it's way through the hull laminate to the transom, where it found a way out into the bilge where the stringers meet the transom on both sides. Going to grind out the hull and upper portion of those tubes, have the yard set up a vacuum system to suck all the moisture out of the laminate, and then reglass everything, drill out and epoxy the four bolt holes for the exhaust ports on each side, redrill the holes and reinstall everything.

Hard to believe I'm the only Searay owner that has ever experienced this issue. Seems like an obvious failure point the way they inserted the tubes flush with the hull. Thank God the hull isn't cored or I'd really be screwed.

Will update with photos as we complete the repairs.

https://www.amazon.com/photos/shared/w9c3hHDDTx-87E-abBXRqg.HuelMv6iiM9RH4ONt2uMGF
 
bfernald0 said:
Very interesting findings. Pulled the boat (3d time) and removed the exhaust ports and sanded off the bottom paint and gelcoat. After an hour or so we observed water seeping out between the exhaust tubes and the hull. As you can see, Sea Ray used prefab 6 inch fiberglass tubes and glassed them in flush with the hull. It appears that over time, the exhaust pressure, vibration, etc. forced water between the outside of the tube and the hull. It ended up working it's way through the hull laminate to the transom, where it found a way out into the bilge where the stringers meet the transom on both sides. Going to grind out the hull and upper portion of those tubes, have the yard set up a vacuum system to suck all the moisture out of the laminate, and then reglass everything, drill out and epoxy the four bolt holes for the exhaust ports on each side, redrill the holes and reinstall everything.

Hard to believe I'm the only Searay owner that has ever experienced this issue. Seems like an obvious failure point the way they inserted the tubes flush with the hull. Thank God the hull isn't cored or I'd really be screwed.

Will update with photos as we complete the repairs.

https://www.amazon.com/photos/shared/w9c3hHDDTx-87E-abBXRqg.HuelMv6iiM9RH4ONt2uMGF
Click to expand...
Seems very unusual. Maybe someone else has heard of it, but i haven’t. The hulls are solid glass. I cant see how an open exhaust would have enough back pressure to go through that distance of laminate and through the transom and back to a stringer . Maybe a major impact might cause stress cracks large enough to go that far, but i can’t see how it could happen otherwise. Maybe your boat was built with bad resin or something.
 
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When you look at at it from under the hull, it's only about 18 inches from those tubes to the transom. This boat sat at a dock for many years (had only 180 hours when it bought it in 2019), before i bought it, repowered it, and used the crap out of it. Put a hundred hours on it last year. Maybe all the use after 20 years knocked a few things loose.
 
bfernald0 said:
When you look at at it from under the hull, it's only about 18 inches from those tubes to the transom. This boat sat at a dock for many years (had only 180 hours when it bought it in 2019), before i bought it, repowered it, and used the crap out of it. Put a hundred hours on it last year. Maybe all the use after 20 years knocked a few things loose.
Click to expand...
Good diagnostic work buddy. I nor friends had heard of this. It sounds like you will be back in the water fairly soon.
 
bfernald0 said:
When you look at at it from under the hull, it's only about 18 inches from those tubes to the transom. This boat sat at a dock for many years (had only 180 hours when it bought it in 2019), before i bought it, repowered it, and used the crap out of it. Put a hundred hours on it last year. Maybe all the use after 20 years knocked a few things loose.
Click to expand...
Maybe but all of our boats have sat in the water and been used. Mine has 1060 hrs of use and I don’t baby it. So it’s something unique to your boat. I still think the repower is the major thing that is different with your boat. Why did it need repower if it had only 180 hrs?
 
In thinking about it, we repowered from 7.4s to 8.2s. We also changed the exhaust system from the log style to the water lift system, but i noted at the last haulout that the original side mufflers had not been taken out. Maybe that created an overpressure situation that caused the water intrusion. The fact is however, exhaust was bubbling out of the transom, which leaves only one source. The fact that it occurred on both sides, and the fact that there was no cracking or leaking on the outside of the exhaust tubes into the bilge, however, leads me to believe that this was not a design defect or some sort of post manufacture damage, but a QC issue on this particular hull during production. Who knows.
 
bfernald0 said:
In thinking about it, we repowered from 7.4s to 8.2s. We also changed the exhaust system from the log style to the water lift system, but i noted at the last haulout that the original side mufflers had not been taken out. Maybe that created an overpressure situation that caused the water intrusion. The fact is however, exhaust was bubbling out of the transom, which leaves only one source. The fact that it occurred on both sides, and the fact that there was no cracking or leaking on the outside of the exhaust tubes into the bilge, however, leads me to believe that this was not a design defect or some sort of post manufacture damage, but a QC issue on this particular hull during production. Who knows.
Click to expand...
So glad you found the problem and can remedy it and soon be on the water. Cheers
 
Well, I wanted to share the epilogue on this. After reglassing the hull/tube area and drilling out the existing bolt holes, filling with epoxy and then drilling new ones, we reinstalled the exhaust ports.

Since this was a repower in which we replaced the engines and the log style exhaust with the water lift muffler design, I can't say whether it was something we did that caused this problem in the first place.

One of the things I noted in our original design is we used a short piece of 5 inch hose to connect the exhaust tubes to the tube coming across and down from the mufflers on each side. I'm thinking that using regular exhaust hose at the joint may not have sufficiently isolated the tubes from vibration, as well as the moment arm of the tube above. We therefore added flexible, silicone joints on each side. Also thinking about securing the horizontal portion of the 5 inch tubes to the engine room ceiling. Pics below

https://www.amazon.com/photos/shared/Rx_Didw4QKqGEG-KaWpRgA.a0gIDcBeoWaQR4LKe_Efow


In any event the bilge is now DRY. As such we correctly identifies the problem. Water and exhaust migrating from the tube/hull interface, through the fiberglass and out at two spots on the inside of the transom. Those two spots are now dry!
 
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