Swift Trawler 42 - Leak under lazarette floor

Hello All,

I have a 2006 Beneteau Swift Trawler 42 (US Assembled).

Between the center stringers in my lazarette, just behind the raw water strainer for the generator, the prior owner had a 10" x 10" square cut into the fiberglass subfloor and installed a bilge pump. It seems water was leaking (from somewhere) into the space between the inner fiberglass shell, and the hull.

The leak is slow, maybe 1/2 gallon per day, and does not seem to increase when the boat is in motion. The added bilge pump takes care of the issue, but I'd rather find the leak!

I've checked in the transom area around the rudder posts, screws that hold the trim tabs, etc. and that area is dry. On the haul out when I purchased the boat (April 2017), they checked the strut mounts, the thru-hull for the A/C raw water intake, and the ground plate screws from under the boat and everything seemed sealed. Unfortunately, these go through the inner fiberglass hull liner, so it's not possible to inspect the actual inside hull attachment.

I'm wondering if any other ST 42 owners have experienced a similar problem, and if so, if you found the source.

Thanks in advance!

Tom

Is this Beneteau version a solid FRP or cored hull? Did the boat survey discuss this issue and probable causes?

sunchaser said:

Is this Beneteau version a solid FRP or cored hull? Did the boat survey discuss this issue and probable causes?

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Hi, the hull is "foam" corede and the deck and superstructure are cored with balsa. I do not know the true hull points, I hope solid structure there.

NBs

North Baltic sea said:

Hi, the hull is "foam" corede and the deck and superstructure are cored with balsa. I do not know the true hull points, I hope solid structure there.

NBs

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Not 100% sure, but I believe Beneteau specs the area below the water line as solid, and no core material.

I take it you have checked to see if it is salt water or fresh?
Where are the AC condensate drains?

Have you consulted the factory, especially on accessing "the inner fiberglass hull liner"?

Thanks all for your questions.

Attached are some photo's of the area in question.

There are three layers in the lazarette.

1. Top fiberglass gelcoat shell. About 1/8" thick. it's thin enough that it's cracked through and is springy when stepped on.
2. Air gap. About 1/2", partially filled with 5200 or something similar. (The 5200 stuff looks factory original as I can see the pattern of the top fiberglass layer where it's been removed).
3. Fiberglass hull. (where the bilge pump and switch have been screwed in)

The water is flowing into the gap between the layers (not from the of the top layer). I've wet-vac'ed the area dry, and it takes about an hour before you see the first signs of water. I've also checked all of the hoses, pumps, strainers etc in this area and find no signs of leaks. All of these are above the top shell.

The actual bilge for the boat is in the keel which is lower than this area by a good 8-10". This area is at the same level as the engine room floor, and is separated from that by a stringer. Given that the bilge is relatively dry, I'm pretty sure that this area is isolated from the engine room/bilge area.

I have not spoken to Beneteau on this. I will try to find a US contact for them and see if I can get some "Support technique".

Here are a few photos of the area with the problem. Note that the gap is large enough that I can stick my finger into it.

Answers to a few more of the questions:

- When we put in new transducers (more forward than this position), the hull was solid fiberglass.

- The survey called out the bilge pump in the area as needing a new float switch. But did not discuss that it should not have been there in the first place. I'm the third owner, and the survey from when the last owner bought it shows the pump, but also does not discuss the source of the leak. So this was installed by the first owner who had the boat for about 2 years.

- I'm in fresh water, so the water is fresh, but when we first looked at it, the boat was in salt water, and the water was salt. While there are hoses and pumps in that area, they are all above the top shell and show no signs of leaking.

- There are two visible thru-hulls in this area. The raw water intake for the air conditioner, and a 1/4" bolt with a ground wire on it. From photos of the haul-out, it looks like the ground plate.

Currently my chief theory is the raw water through hull for the A/C is leaking.

KSF said:

Currently my chief theory is the raw water through hull for the A/C is leaking.

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Two questions
1. Can you isolate the AC through hull and monitor it for leakage?
2. What is the purpose of the liner or false bottom?

Also you may want to look into how the various under water through hulls were installed, both during the build and aftermarket. It is not uncommon that poorly installed through hulls have to be removed and properly rebedded.

In some cases backing blocks were not used and the piping flexes in the hole eventually leading to leakage. Unfortunately common and if hidden from view a potential disaster waiting to happen.

Thanks Sunchaser!

1) The purpose is mostly cosmetic to make the area smooth. Removal is not really an option as it would require pulling the generator and fresh water tanks. the liner covers edge to edge of the whole back of the boat and wraps the stringers.

2) It might be possible to cut the top layer around the through hulls to see if that's where it's coming from. I'm hoping to find another ST 42 owner that had the same issue and has already found the problem to avoid doing a lot of cutting.

On my next haulout I'm going to have the through hulls in that area replaced and rebedded, it can't hurt and it may solve my problem. When they do that I'm planning on having them remove the top liner in that area so that they don't have to pass through two layers of material with a gap. I'd hope that they put some sort of flange fitting to sandwich the actual hull, but I can't see it with the top layer.

KSF said:

..... I'm the third owner, and the survey from when the last owner bought it shows the pump, but also does not discuss the source of the leak. So this was installed by the first owner who had the boat for about 2 years....

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The boat would have been under warranty with the original owner, who resorted to the bilge pump fix. It`s a desperation kind of "solution", "we can`t fix the leak but we can pump out the water it lets in".
I hope you solve it, it`s quite possible Beneteau could not. Can you contact the original owner for more information?

Had the same problem last summer-looked everywhere!!! finally found it after pulling the aft lazarett outboard apart and crawled outboard-the leak was coming from the starboard exhaust flange!! Under the 8in hose found constant drips at rest but underway it leaked 5gpd.
Pulled the boat ,pulled hose off,unbolted /pulled the flange(no cracks),rebedded and reassembled. Not drop since!
Bob N-LindaLee 2005 Beneteau 42

reelcompromise said:

Had the same problem last summer-looked everywhere!!! finally found it after pulling the aft lazarett outboard apart and crawled outboard-the leak was coming from the starboard exhaust flange!! Under the 8in hose found constant drips at rest but underway it leaked 5gpd.
Pulled the boat ,pulled hose off,unbolted /pulled the flange(no cracks),rebedded and reassembled. Not drop since!
Bob N-LindaLee 2005 Beneteau 42

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Any idea if this could be an issue on the updated 44? Was the exhaust design changed at all? Is it solid around it or possible water intruded into the hull itself and not just the bilge area?

reelcompromise said:

Had the same problem last summer-looked everywhere!!! finally found it after pulling the aft lazarett outboard apart and crawled outboard-the leak was coming from the starboard exhaust flange!! Under the 8in hose found constant drips at rest but underway it leaked 5gpd.
Pulled the boat ,pulled hose off,unbolted /pulled the flange(no cracks),rebedded and reassembled. Not drop since!
Bob N-LindaLee 2005 Beneteau 42

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Thanks for the information. I didn't think that there was a water path from the outboard area where the water tanks and exhaust are to the center of the lazarette, but I guess that's not correct! Thanks for the information. I'll have the exhaust ports looked at when I pull the boat in the spring.

Cheers,

Tom

The exhaust flange leak

Surprising enough the exhaust flange leak DID sneak into and under the lazarette sub floor and if left alone for 1-2 days bubbled up. Looking for the leak after pulling the boat is a waste if time-you need to sneak into the aft corners to see/find these leaks while in the water
Good luck
Bob

about to survey in a couple days... has anyone with the newer model 44 had this issue or checked for it? i'm assuming its going to be close to impossible to have this inspected during a survey..? thanks!

mystery said:

about to survey in a couple days... has anyone with the newer model 44 had this issue or checked for it? i'm assuming its going to be close to impossible to have this inspected during a survey..? thanks!

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Won`t there be water where it should not be if the leak exists? I`m guessing the boats have shaft seals and run a dry bilge, but could be wrong.
If you or the surveyor have one of those long flexible shaft cameras it might get you a look in there.

BruceK said:

Won`t there be water where it should not be if the leak exists? I`m guessing the boats have shaft seals and run a dry bilge, but could be wrong.
If you or the surveyor have one of those long flexible shaft cameras it might get you a look in there.

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i thought the water was not showing up in the bilge but in an aft compartment that had to be taken apart to see? i just want to know if the 44 has the same design as the 42 and this area should be inspected.

Rebedding stuff before you find the leak is a waste of money. Try shutting off stuff that brings in outside water like AC and see if it still loeak.
Paper towels place in the bilge might point to the source.

You can cut away more of that thin stuff leaving an edge then later put a metal plate over the hole for better visibility.

Thanks for the ideas

Hello All,

Thanks for the ideas and insight. I took reelcompromise's advice and checked deep in the stern. I do see some signs of a leak on the starboard exhaust port. It's doesn't appear to be the same volume that I'm seeing, but it does indicate that it's involved.

I'm going to the restaurant supply store today and getting myself a couple of bigger bottles of food coloring. (Red & Blue) and will put some red in that area and see how long it takes to leach into the water in that bilge area. I'll put the blue on the port side. If I see "Green" (red & blue make green), well then I'm dawning the life jacket!

I have tried shutting off all of the water sources in that area (generator and A/C) but the water still comes in, so I'm fairly sure that that isn't the source. The most likely other possibility, is that the through hull for the A/C water intake is in that area and it's possible that's what is leaking, when I have the boat hauled for it's next bottom paint, I'm going to have that, the ground plate, and the exhaust ports re-seated as a matter of course.

My mechanic is coming to do the valves and injectors on my engine next week and I'm going to discuss cutting out the thin stuff with him. I don't see an issue doing it, as it's all cracked anyway. It almost looks like it's main purpose was to retain any leaks from the A/C and Generator raw water systems to keep it away from the hull. It's not doing that job so can probably be removed. Watching where the water runs in from when I wet-vac the area dry, and the volume, what ever is leaking, it's got to be a steady drip.

As for the Swift 44. My understanding (third party comments) is that the 44 uses the same hull mold as the 42 (it's the extended swim platform that add the extra 2'). I've not see inside the 44, but if you have a channel in your lazarette that holds your a/c pump, a/c thru hull, a/c raw water strainer, and generator exhaust & raw water strainer, it's probably a similar design.

Again Thanks to all. I'll update as I have more information.

Unfortunately I could not crawl into the bilge myself during survey due to an injury. Is the "exhaust flange" what is circled in yellow in the attached picture? If so, the surveyor crawled in on the ST 44 and said it looks fine for both port and starboard sides. Thank you

For what it's worth, I deliberately flooded my lazarette floor to see if the water would run forward to the bilge between the engines, which it did. Of course, when underway this would not be the case.

Hi KSF any updates?

No updates yet

No updates as yet. I (embarrassed look) had a grounding and bent a prop blade two weeks ago while on a trip. Luckily I was able to get the boat hauled and the props straightened in New Bern, NC. (Thanks to Bridgeton Boatworks, excellent service!) It was a short haul, just pulled the props, had them straightened and put back on, less than 24 hours. They never even took it off the travel lift.

I didn't have time to do a full investigation, however, we did look at the exhaust ports, and I was able to see that there are gaps around the flange where the packing has disintegrated, so I'm making the assumption that that's the source.

I have a regularly scheduled haulout planned in the spring and will have them re-packed then.

On a side note, we had both props tuned in the process of fixing the bent blade. On the port prop (the one we hit), one blade was out 3", two more were out about 1.5" and one about .5". On the starboard prop, which we didn't strike, the blades were out between .5" and .75".

It's possible that the prior owner had a strike, but the guy at the Propeller Shop, said that over time, brass props will come out of true due to the force of water, especially on heavier higher horsepower boats. He suggested having the props checked about every 3 years or so.

When we got the boat back in the water, we noticed a definite difference in performance. We got at least another 1.5 - 2 knots at the same RPM settings.

Beautiful boat!

Engine exhaust flange repacking

It is a big job to get access to the flange,pull off the hose,etc .I did it because there was sea water dripping at rest and underway down the underside of the exhaust pipe into the bilge. I did not do the non leaking side. It probably cost $1000 not counting hauling. 18 months later no leaks either side

Bob Nordstrom
LindaLee
2005 42ft